Not alive; non-biological; for example, temperature and mixing are abiotic factors that influence the O2 content of lake water whereas photosynthesis and respiration are biotic factors that affect O2 solubility.
A dredgeability factor. (See also abrasiveness.)
Synonym : Abrasiveness
A rock or clay platform which has been worn by the processes of abrasion.
1. The mechanical wearing, grinding, scraping, or rubbing away of pumping equipment components and pipelines by friction or impact, or both.
2.The mechanical wearing away by rock material transported by wind or water.
(ASTM D 653) The property of a material to remove matter when scratching and grinding another material.
The foundation along the sides of the valley or gorge against which the dam is constructed.
Erosion at a rate greater than normal, usually associated with activities of man which reduce plant cover and increase runoff. (See geologic erosion).
Synonym : Geologic erosion
Type I-buying back equitable time extensions otherwise due the construction contractor under the contract clause of his contract which covers unforeseen causes beyond his control and without his fault or negligence. These include fires, floods, strikes, and unusually severe weather. type II-buying back equitable time extensions otherwise due the construction contractor under other contract clauses of his contract, such as "Changes" and "Differing Site Conditions."
The record from an accelerometer showing acceleration as a function of time.
A device used in wave buoys for measuring acceleration.
In quality assurance, a determination of acceptability of a material, product, or process based on statistical or mathematical principles.
Acceptance sampling plan
In quality assurance, the specified procedure for effecting the acceptance sampling and testing for a given quality characteristic. The plan includes the lot, or block, size, the number and locations of samples, and the acceptance criteria.
In quality assurance, the sampling and testing of a lot, or block, of material or construction processing for comparison with specified requirements, resulting in acceptance or rejection of the lot or block.
(EM 1110-2-1003) A portion of an overall dredging contract over which payment is computed, based on estimated progress per payment period. A contract may have any number of acceptance sections.
See post dredge hydrographic survey.
The act of an authorized representative of the government by which the government, in recognition of partial or complete performance of a contract, accepts ownership of materials, supplies, equipment, and facilities or accepts rendered services.
Tidal datums and Greenwich high and low water intervals obtained through primary determination or simultaneous observational comparisons made with a primary control tide station in order to derive the equivalent of a 19-year value.
A beach ridge located inland from the modern beach, representing an ancient beach deposit and showing that the coast has been built out seaward. It is often accentuated by the development of dunes.
|Accretion||May be either natural or artificial. Natural accretion is the buildup of land, solely by the action of the forces of nature, on a beach by deposition of water- or airborne material. Artificial accretion is a similar buildup of land by reason of an act of man, such as the accretion formed by a GROIN, BREAKWATER, or beach fill deposited by mechanical means. Also AGGRADATION.||Coastal Engineering|
|The difference between the approximate solutions obtained using a numerical model and the exact solution of the governing equations. The degree of conformity of a measure to a standard or true value.||Coastal Engineering|
|Acid Neutralizing Capacity (ANC)|
Acid neutralizing capacity (ANC) is the equivalent sum of all bases or base-producing materials, solutes plus particulates, in an aqueous system that can be fitrated with acid to an equivalence point. This term designates titration of an “unfiltered” sample (formerly reported as alkalinity).
|Acid rain||Precipitation having a ph lower than the natural range of ~5.2 - 5.6; caused by sulfur and nitrogen acids derived from anthropogenic emissions.||Coastal Engineering|
|Acid||A solution that is a proton (H+) donor and has a pH less than 7 on a scale of 0-14. The lower the pH the greater the acidity of the solution.||Coastal Engineering|
The process by which acids are added to a water body, causing a decrease in its buffering capacity (also referred to as alkalinity or acid neutralizing capacity), and ultimately a significant decrease in pH that may lead to the water body becoming acidic (pH < 7).
|Acidity||A measure of how acid a solution may be. A solution with a pH of less than 7.0 is considered acidic. Solutions with a pH of less than 4.5 contain mineral acidity (due to strong inorganic acids), while a solution having a pH greater than 8.3 contains no acidity.||Coastal Engineering|
A current measuring instrument employing the transmission of high frequency acoustic signals in the water. The current is determined by a Doppler shift in the backscatter echo from plankton, suspended sediment, and bubbles, all assumed to be moving with the mean speed of the water. Time gating circuitry is employed which uses differences in acoustic travel time to divide the water column into range intervals, called bins. The bin determinations allow development of a profile of current speed and direction over the entire water column.
The ADCP can be deployed from a moving vessel, tow, buoy, or bottom platform. In the latter configuration, it is nonobtrusive in the water column and thus can be deployed in shipping channels.
|Acoustic impedance||Rapid seismic technique which delineates bottom and subbottom materials through mathematical processes involving signal attenuation and reflectivity. Accurate estimates of density and material-type can be made on a near continuous basis providing calibrations can be established through laboratory tested boring samples.||Coastal Engineering|
|Acoustic resuspensions measurement system (ARMS)||(DRP Tech Note 1-05) developed by the DRP, ARMS is an integrated ensemble of specialized underwater sensors designed to accurately measure in situ properties of the bottom boundary layers in open-water areas. ARMS provides the necessary information on whether a dredged material placement site is dispersice.||Coastal Engineering|
1. Adjective used in conjunction with a basic property of sound, e.g., acoustic energy.
2. Containing, producing, arising from, actuated by, related to, or associated with sound. "Acoustic" is used when the term being qualified designates something that has the properties, dimensions, or physical characteristics associated with sound; "acoustical" is used when the term being qualified does not designate explicitly something that has such properties, directions, or physical characteristics.
|Acre-foot||The quantity of water required to cover one acre of land to a depth of one foot; equivalent to 43,560 cubic feet of water or 325,851 gallons of water.||Coastal Engineering|
|The level area adjacent to a stream channel that is subject to frequent overflow.|||
|A margin of a continental plate consisting of a continental shelf and slope, and an oceanic trench or basin.||Coastal Engineering|
|Activity index||The ratio of (1) the plasticity index to (2) the percent clay, i.e., the percent of the soil binder (material finer than the No. 40 sieve) that is finer than -0.002 mm. (See also binder; clay; plasticity index.)||Coastal Engineering|
|Actual progress||A measure of the accomplishment of a contractor for a given time period in completing his obligation under the contract. (See also scheduled progress.)||Coastal Engineering|
|Acute toxicity||(Dredged Material Testing Manual) level of mortality by a group of marine organisms that have been affected by the properties of a substance, such as a contaminated sediment. The acute toxicity of a sediment is determined by quantifying the mortality of appropriately sensitive organisms that are put into contact with the sediment, under either field or laboratory conditions, for a specified period.||Coastal Engineering|
|Adaptive management of streams||Adjusting restoration goals, design details, and management of the implementation process as new information becomes available. Adaptive management is an ongoing process of evaluating, planning, implementing, and monitoring. Contrast to boilerplate, cookie-cutter design and management approaches.||Coastal Engineering|
Adenosine triphosphate (ATP) is an organic, phosphaterich compound important in the transfer of energy in organisms. Its central role in living cells makes ATP an excellent indicator of the presence of living material in water. A measurement of ATP therefore provides a sensitive
and rapid estimate of biomass. ATP is reported in micrograms per liter.
|(ASTM D 653) shearing resistance between two unlike materials under zero externally applied pressure.||Coastal Engineering|
|A GROIN whose permeability can be changed, usually with gates or removable sections.||Coastal Engineering|
|Adjusted Discharge||Adjusted discharge is discharge data that have been mathematically adjusted (for example, to remove the effects of a daily tide cycle or reservoir storage).||Coastal Engineering|
|Adjustment in estimated quantity||A contract adjustment pursuant to the contract clause on variation in estimated quantity (e.g., when actual quantity varies + 10 percent from an initially estimated quantity.)||Coastal Engineering|
|Adjustment||Variation of the parameters in a model to ensure a close reproduction by the model of a set of prototype conditions.||Coastal Engineering|
|Administrative change||A unilateral contract change, in writing, that does not affect the substantive rights of the parties.||Coastal Engineering|
|Adr gage||Analog to Digital Recording tide gage. A float or pressure actuated tide gage that records the heights of regular time intervals.||Coastal Engineering|
|Advance (of a beach)|
1. A continuing seaward movement of the shoreline.
2. A net seaward movement of the shoreline over a specified time. Also PROGRESSION.
|Advance dredging||See advance maintenance.||Coastal Engineering|
|Advance maintenance||The additional depth and/or width specified to be dredged beyond the project channel dimensions for the purpose of reducing overall maintenance costs by decreasing the frequency of dredging. This procedure also may facilitate scheduling of dredging activities. Advance maintenance must always be justified.||Coastal Engineering|
|Advance||The distance between the positions of the working spud of a cutterhead dredge before and after each time it walks ahead along the cut. It can also mean the progress made (usually in linear feet) by a dredge during a period of time. This is usually the length dimension used in calculating the volume of dredged material removed.||Coastal Engineering|
1. Changes in a sea water property (salinity, temperature, oxygen content, etc.) that take place in the presence of currents. Also, changes in atmospheric properties in the earth's atmosphere.
2. The process by which solutes are transported by the motion of flowing groundwater.
1. Guaranteed depth with respect to shipping.
2. Minimum depth required related to chart datum and with respect to the required accessibility and safety for navigation.
|Aeolian||See EOLIAN.||Coastal Engineering|
|Aesthetic improvement||(EM 1110-2-5026)A dredged material placement site appearance improvement which makes it more pleasing and acceptable to the general public living and working around the site.||Coastal Engineering|
|A-frame||Structural frame, usually steel, that performs as a crane boom or derrick; minimum of two members spaced wider at bottom attachment than at top to form triangular shape.||Coastal Engineering|
|After dredging survey||(ER 1130-2-307) Hydrographic survey(s) performed after dredging of a required section(s) is completed. This survey is used for clearance, payment, and acceptance purposes. (See also post-dredge hydrographic survey.)||Coastal Engineering|
|Age of diurnal inequality||The time interval between the maximum semimonthly north or south declination of the Moon and the maximum effect of the declination upon range of tide or speed of the current. The age may be computed from the harmonic constants by the formula - age of diurnal inequality = 0.911(K1-01) hours.||Coastal Engineering|
|Age of moon||The time elapsed since the preceding new Moon.||Coastal Engineering|
|Age of parallax inequality||The time interval between perigee of the Moon and the maximum effect of parallax upon range of tide or speed of the tidal current. This age may be computed from the harmonic constants by the formula age of parallax in equality = 1.837(M2-N2)||Coastal Engineering|
Age of phase inequality
|The time interval between new or full Moon and the maximum effect of these phases upon range of tide or speed of the tidal current. This age may be computed from the harmonic constants by the formula age of phase inequality = 0.984(S2-M2) hours.||Coastal Engineering|
|Age of tide||See age of phase inequality.||Coastal Engineering|
|Age, wave||The ratio of wave velocity to wind velocity (in wave forecasting theory).||Coastal Engineering|
|Agger||See double tide.||Coastal Engineering|
|Aggradation||The geologic process by which stream beds, floodplains, and the bottoms of other water bodies are raised in elevation by the deposition of material eroded and transported from other areas. It is the opposite of degradation. See accretion.||Coastal Engineering|
|Aggravation||The geologic process by which stream beds, flood plains, and the bottoms of other water bodies are raised in elevation by the deposition of material eroded and transported from other areas. It is the opposite of degradation.||Coastal Engineering|
1. (NAVFAC DM-26.3) a group or mass of distinct things gathered together.
2. The natural sands, gravels, and crushed stones used in the manufacture of concrete. Aggregate for concrete commonly is obtained from alluvial stream deposits or from rock quarries.
|(Webster's New Collegiate Dictionary) the collection of units or parts into a mass or whole.||Coastal Engineering|
|See dredge, other, agitation.||Coastal Engineering|
|Agitation dredging||The practice of hydraulically or mechanically lifting sediment from the bottom of a dredging site and into the upper water column layers. Tidal and river currents can act on the sediment to move it from the dredging site. Agitation dredging is normally used with fine-grained sediments. Allowing the hoppers of hopper dredges to overflow is an example of agitation dredging.||Coastal Engineering|
|An Indian Ocean current setting southwestward along the southeast coast of Africa.||Coastal Engineering|
|Aid to navigation||Generally, a device external to a craft, serving the interests of safe navigation and designed to assist in the determination of the position of a craft, a safe course, or to warn of dangers and obstructions; e.g., buoys, beacons, fog signals, lights, etc. The expression "aid to navigation" should not be confused with "navigational aid", a broad expression covering any instrument, device, chart, method, etc. intended to assist in the navigation of a craft. In British usage, the two expressions are used without distinction. (See also navigational aid.)||Coastal Engineering|
|Coastal EngineeringAids to navigation||Devices external to a vessel and located either in the water, above the water, or on shore, that are intended to assist a navigator in determining his position or safe course, or to warn him of dangers or obstructions to navigation. Examples are buoys, lights, and dayboards.||Coastal Engineering|
|Air lift dredge||See dredge, air lift.||Coastal Engineering|
|Air-void ratio||(ASTM D 653) The ratio of (1) the volume of air space, to (2) the total volume of voids in a soil or rock mass. (See also degree of saturation.)||Coastal Engineering|
|Alaska current||A North Pacific Ocean current setting counterclockwise along the coasts of Canada and Alaska in the Gulf of Alaska.||Coastal Engineering|
|Alaskan stream||A North Pacific Ocean current setting westward along the south side of the Aleutian Islands. It is an extension of the Alaska Current.||Coastal Engineering|
Simple single-celled, colonial, or multi-celled, aquatic plants. Aquatic algae are (mostly) microscopic plants that contain chlorophyll and grow by photosynthesis, and lack roots and stems ((non-vascular), and leaves. They absorb nutrients (carbon dioxide, nitrate, ammonium, phosphate and micronutrients) from the water or sediments, add oxygen to the water, and are usually the major source of organic matter at the base of the food web in lakes. Freely suspended forms are called phytoplankton;
forms attached to rocks, stems, twigs, and bottom sediments are called periphyton.
|Algal Growth Potential (AGP)||Algal growth potential (AGP) is the maximum algal dry weight biomass that can be produced in a natural water sample under standardized laboratory conditions. The growth potential is the algal biomass present at stationary phase and is expressed as milligrams dry weight of algae produced per liter of sample. (See also “Biomass” and “Dry weight”)||Coastal Engineering|
|Algorithm||A procedure for solving a mathematical problem in a finite number of steps that frequently involves repetition of an operation. A step by step procedure for solving a problem or accomplishing an end. A set of numerical steps or routines to obtain a numerical output from a numerical input.||Coastal Engineering|
|Alignment||The course along which the center line of a channel, canal or drain is located.||Coastal Engineering|
|Aliquot||A fractional part representative of the whole.||Coastal Engineering|
|Alkalinity||Alkalinity is the capacity of solutes in an aqueous system to neutralize acid. This term designates titration of a “filtered” sample.||Coastal Engineering|
|Allochthonous material||Organic material that falls into a stream from the surrounding land.||Coastal Engineering|
|Allowable overdepth||Dredging paid for below the required channel section as an allowance for normal and accepted inaccuracies in achieving an exact digging depth. The contractor is paid for only that portion of the overdepth actually removed. Overdepth in excess of two feet is not allowed unless approved by the Division Commander.||Coastal Engineering|
|Alluvial channel||See Alluvial Stream.||Coastal Engineering|
|Alluvial deposits||Detrital material which is transported by a river and deposited - usually temporarily - at points along the flood plain of a river. Commonly composed of sands and gravels.||Coastal Engineering|
|Alluvial fan||A conical, or fan, shaped deposit at the base of a mountain range where the mountain stream encounters the lesser slope of the valley floor. The deposits are generally coarse and alluvial fans most often occur in arid and semi-arid regions where streamflow is ephemeral and vegetation cover is sparse.||Coastal Engineering|
|Alluvial features||Landforms created by rivers, such as floodplains. Sediments are typically round and smooth from water erosion.||Coastal Engineering|
|Alluvial plane||A plain bordering a river, formed by the deposition of material eroded from areas of higher elevation.||Coastal Engineering|
|Alluvial stream||A stream whose channel boundary is composed of appreciable quantities of the sediments transported by the flow, and which generally changes its bed forms as the rate of flow changes.||Coastal Engineering|
|Alluvial||Pertains to alluvium deposited by a stream or flowing water.||Coastal Engineering|
1. A general term for all detrital deposits resulting directly or indirectly from the sediment transported by (modern) streams; thus including the sediments laid down in river beds, floodplains, lakes, fans, and estuaries.
2. Sediments deposited by flowing water. Deposits can be made by streams on river beds, flood plains, and alluvial fans.
|Alongshore||Parallel to and near the shoreline; LONGSHORE.||Coastal Engineering|
|Alpha geek||The most technically accomplished or skillful person in some implied context. "Ask Norm, he's the alpha geek here."||Coastal Engineering|
|Alternate bars||Bars formed in a staggered pattern near the banks of channels.||Coastal Engineering|
|Altimeter, laser||An instrument that determines altitude by measuring the length of time needed for a pulse of coherent light to travel from the instrument to the surface and back, and multiplies half this time by the speed of light to get the straight-line distance to the surface.||Coastal Engineering|
|Altimeter, lidar||See ALTIMETER, LASER.||Coastal Engineering|
|Altimeter||An instrument that determines its distance above a particular surface.||Coastal Engineering|
|Ambient water||See background water.||Coastal Engineering|
|ambrose draghead||See drag head.||Coastal Engineering|
|Amidships||(Huston. Hydraulic Dredging Principles...) Generally speaking, the middle section of a vessel. The point of intersection of two lines, one drawn along from the stem to the stern, the other across the beam, or widest part of the vessel.||Coastal Engineering|
|Amphidromic point||A point of no amplitude of the observed or a constituent tide.||Coastal Engineering|
|Amphidromic region||An area surrounding an amphidromic point from which the radiating cotidal lines progress through all hours of the tidal cycle.||Coastal Engineering|
|Amplitude (h)||One-half the range of a constituent tide. By analogy, it may be applied also to the maximum speed of a constituent current.||Coastal Engineering|
1. The magnitude of the displacement of a wave from a mean value. An ocean wave has an amplitude equal to the vertical distance from the stillwater level to wave crest. For a sinusoidal wave, amplitude is one-half the wave height.
2. The semirange of a constituent tide.
|Anaerobic||Technically this means "without air" but in limnology it is used synonymously with "anoxic."||Coastal Engineering|
|Analog depth recorder||(EM 1110-2-1003) A graphical recording echo sounder.||Coastal Engineering|
|Analog||As used in the National Ocean Service, a continuous measurement or a continuous graphic display of data. (See also ADR gage; marigram.)||Coastal Engineering|
|Analysis, harmonic||See harmonic analysis.||Coastal Engineering|
|Analytical model||Alternate bars Mathematical model in which the solution of the governing equations is obtained by algebraic analysis.||Coastal Engineering|
|Analyzer, harmonic||See harmonic analyzer.||Coastal Engineering|
|Anchor barge||See barge.||Coastal Engineering|
|Anchor boom||Special boom extending outward from the forward portion of a dredge for lifting and resetting swing anchors.||Coastal Engineering|
|Anchor ice||Spongy underwater ice formed on a submerged object or attached to the bottom of a shallow body of water which is itself not frozen; syn. bottom ice||Coastal Engineering|
|Anchor line||See line.Coastal Engineering||Coastal Engineering|
Any of various devices for dropping by a chain, rope, or cable to the bottom of a body of water to prevent or restrict the motion of a vessel or other floating object.
a. belly-anchors used for maintaining a straight floating pipeline against wind or current. Usually connected to a winch mounted on a pontoon attached to the pipeline.
b. Danforth-it has a holding power of 17 to 1000 times its own weight.
c. patent-also called stockless anchor; it has a holding power of 2 to 4 times its own weight.
d. swing-the anchors set to each side of a cutter head or suction dredge and to which the swing wires are attached.
e. mushroom-holding power of ---- to ------- times its weight.
|Anemometer||A device used to measure wind speed and direction.||Coastal Engineering|
|Angle of friction||See angle of internal friction.||Coastal Engineering|
|Angle of incidence||Angle between direction of motion of waves and a line perpendicular to surface the waves are striking.||Coastal Engineering|
|Angle of internal friction (angle of friction) (angle of shearing resistance)|
Angle representing the relationship of shearing resistance to normal stress acting on the sliding surface within a soil mass during shear; angle between the axis of normal stress and the tangent to the Mohr envelope at a point representing a given failure-stress condition for the solid material.
|Angle of reflection|
Angle between direction of motion of waves and a line perpendicular to surface the waves are reflected from.
|Angle of repose||(ASTM D 653) Angle between the horizontal and the maximum slope that a soil assumes through natural processes. For dry granular soils the effect of the height of slope is negligible; for cohesive soils the effect of height of slope is so great that the angle of repose is meaningless.||Coastal Engineering|
|Angular grains||(Mod. from ASTM D 653) Coarse grains which possess well-defined edges formed at the intersection of roughly planar faces.||Coastal Engineering|
|Angular velocity of the earth's rotation||Time rate of change of angular displacement relative to the fixed stars. It is equal to 0.729,211 x 10-4 radian/second.||Coastal Engineering|
|Angularity of particles||(ASTM D 2488) Relationship between edges and faces of the surface of coarse grains. angular particles-particles have sharp edges and relatively plane sides with unpolished surfaces. subangular particles-particles are similar to angular description but have rounded edges. subrounded particles-particles have nearly plane sides but have well-rounded corners and edges. rounded particles-particles have smoothly curved sides and no edges.||Coastal Engineering|
|Anions||Negatively charged ions.||Coastal Engineering|
|Anisotropic||Exhibiting properties with different values when measured along axes in different directions.||Coastal Engineering|
|Anisotropy||The condition under which one or more of the hydraulic properties of an aquifer vary according to the direction of flow.||Coastal Engineering|
|Annual 7-day Minimum|
Annual 7-day minimum is the lowest mean value for any 7-consecutive-day period in a year. Annual 7-day minimum values are reported herein for the calendar year and the water year (October 1 through September 30). Most low-flow frequency analyses use a climatic year (April 1-
March 31), which tends to prevent the low-flow period from being artificially split between adjacent years. The date shown in the summary statistics table is the initial date of the 7-day period. (This value should not be confused with the 7-day, 10-year low-flow statistic.)
|Annual inequality||Seasonal variation in water level or current, more or less periodic, due chiefly to meteorological causes.||Coastal Engineering|
Annual runoff is the total quantity of water that is discharged (“runs off”) from a drainage basin in a year. Data reports may present annual runoff data as volumes in acrefeet, as discharges per unit of drainage area in cubic feet per second per square mile, or as depths of water on the
drainage basin in inches.
|Annual series||The discharge record consisting of the greatest discharge occurring in each year.||Coastal Engineering|
Pertaining to the periodic return of the Moon to its perigee or the Earth to its perihelion. The anomalistic month is the average period of the revolution of the Moon around the earth in respect to lunar perigee, and is approximately 27.554550 days in length. The anomalistic year is the average period of the revolution of the Earth around the Sun in respect to perihelion, and is approximately 365.2596 days in length.
|anomaly, as in astronomy|
The angle made at any time by the radius vector of a planet or moon with its line of apsides, the angle being reckoned from the perihelion or perigee in the direction of the body's motion. It is called the true anomaly when referred to the actual position of the body, and mean anomaly when referred to a fictitious body moving with a uniform angular velocity equal to the average velocity of the real body and passing perihelion or perigee at the same time.
1. A departure from the expected or normal.
2. A geological feature, esp. in the subsurface, distinguished by geological, geophysical, or geochemical means, which is different from the general surroundings and is often of potential value.
|Anoxia||Condition of being without dissolved oxygen (O2).||Coastal Engineering|
Refers to ocean basins that contain little or no dissolved oxygen and hence little or no benthic marine life. These conditions arise in basins or fjords where physical circulation of seawater is limited.
|Anthropogenic||Human caused.||Coastal Engineering|
|Antidunes||A series of general sinusoidal-shaped bed forms that commonly move upstream accompanied by in-phase waves on the water surface. Antidunes develop in a sand-bed stream where the Froude number is close to or greater than one.||Coastal Engineering|
|Antilles current||A North Atlantic Ocean current setting northwestward along the northeast coasts of the Bahama Islands.||Coastal Engineering|
|Anti-null antennae||Device which prevents an area of no signal from affecting electronic distance measuring equipment measurements.||Coastal Engineering|
|Anywhere fix||(Trimble Navigation. GPS...) The ability of a receiver to start position calculations without being given an approximate location and approximate time.||Coastal Engineering|
|Aphelion||The point in the Earth's orbit farthest from the Sun.||Coastal Engineering|
|Apogean tides or tidal currents||Tides of decreased range or currents of decreased speed occurring monthly as the result of the Moon being in apogee. The apogean range (An) of the tide is the average range occurring at the time of apogean tides and is most conveniently computed from the harmonic constants. It is smaller than the mean range, where the type of tide is either semi-diurnal or mixed, and is of no practical significance where the type of tide is predominantly diurnal.||Coastal Engineering|
|Apogee||The point in the Moon's orbit farthest from the Earth.||Coastal Engineering|
|Apparent cohesion||Cohesion in granular soils due to capillary forces.||Coastal Engineering|
Apparent secular trend
The nonperiodic tendency of sea level to rise, fall, and/or remain stationary with time. Technically, it is frequently defined as the slope of a least-squares line of regression through a relatively long series of yearly mean sea-level values. The work "apparent" is used since it is often not possible to know whether a trend is truly nonperiodic or merely a segment of a very long (relative to the length of the series) oscillation.
|Apparent time||Time based upon the true position of the Sun as distinguished from mean time, which is measured by a fictitious sun moving at a uniform rate. Apparent time is that shown by the sundial, and its noon is the time when the Sun crosses the meridian. The difference between apparent time and mean time is known as the equation of time. Although quite common many years ago, apparent time is seldom used now.||Coastal Engineering|
|Appurtenant feature||Any physical feature other than the dam, such as the spillway, outlet, powerhouse, penstock, tunnels, etc.||Coastal Engineering|
|Apron||Layer of stone, concrete or other material to protect the toe of a structure.||Coastal Engineering|
The points in the orbit of a planet or moon which are the nearest and farthest from the center of attraction. In the Earth's orbit these are called perihelion and aphelion, and in the Moon's orbit, perigee and apogee. The line passing through the apsides of an orbit is called the line of apsides.
(EM 1110-2-5026) A term applied to any commercial aquatic farming operation for freshwater or saltwater organisms such as crayfish, shrimp, or catfish. (See also beneficial use; mariculture.)
|Aquatic dredged material placement|
Comprises all dredged material placement options under which the dredged material is submerged under water and remains water-saturated after placement terminates. (Differs from open-water dredged material placement. Open-water dredged material placement does not specify placed material be submerged and remain saturated.) (See also open-water dredged material placement, thalweg dredge material placement.)
|Aquatic habitat||(EM 1110-2-5026) Typical submerged communities extending from near sea, river, or lake level down several feet, such as tidal flats, oyster beds, clam flats, seagrass beds, or fishing reefs.||Coastal Engineering|
|Aquatic material placement||Comprises all placement options under which the dredged material is submerged under water and remains water-saturated after placement terminates.||Coastal Engineering|
|Aquatic respiration||Refers to the use of oxygen in an aquatic system including the decomposition of organic matter and the use of oxygen by fish, algae, zooplankton, aquatic macrophytes, and microorganisms for metabolism.||Coastal Engineering|
|Aquiclude||A low-permeability unit that forms either the upper or lower boundary of a groundwater flow system.||Coastal Engineering|
|Aquifer, confined||An aquifer that is overlain by a confining bed. The hydraulic conductivity of the confining bed is significantly lower than that of the aquifer.||Coastal Engineering|
|Aquifer, perched||A region in the unsaturated zone where the soil may be locally saturated because it overlies a low-permeability unit.||Coastal Engineering|
|Aquifer, semiconfined||An aquifer confined by a low-permeability layer that permits water to slowly flow through it. During pumping of the aquifer, recharge to the aquifer can occur across the confining layer. Also known as a leaky artesian or leaky confined aquifer.||Coastal Engineering|
|Aquifer, unconfined||Also known as water-table and phreatic aquifer. An aquifer in which there are no confining beds between the zone of saturation and the surface. The water table is the upper boundary of unconfined aquifers.||Coastal Engineering|
1. A geologic formation that is water-bearing, and which transmits water from one point in the formation to another.
2. Rock or sediment in a formation, group of formations, or part of a formation that is saturated and sufficiently permeable to transmit significant quantities of water to wells and springs.
|Aquifuge||An absolutely impermeable unit that will neither store nor transmit water.||Coastal Engineering|
|Aquitard||A low-permeability unit that can store groundwater and also transmit it slowly from one aquifer to another.||Coastal Engineering|
|Arc of contact||The angular measure (no. of degrees) that a belt or chain is in contact with a pulley groove. V-belt drives are used for general speed reduction and in some cases to couple diesel engines to the main pump of a dredge. The amount of the arc of contact determines the power capacity of a V-belt.||Coastal Engineering|
|Archipelago||A sea that contains numerous islands; also the island group itself.||Coastal Engineering|
|Architect-engineer, a-e, contract||(EM 1110-2-1003) The type of contract prescribed for procuring hydrographic surveys in accordance with FAR Part 36.||Coastal Engineering|
|Area, usable||The area under the surface of a stream available to aquatic organisms. ||Coastal Engineering|
|Area, weighted usable (WUA)||The area under the surface of a stream, weighted by its suitablity, available to a life stage of an aquatic organism. (see PHABSIM)||Coastal Engineering|
|Argument||See equilibrium argument.||Coastal Engineering|
|Armor layer||Protective layer on a BREAKWATER or SEAWALL composed of armor units.||Coastal Engineering|
|Armor unit or stone||A relatively large quarrystone or concrete shape that is selected to fit specified geometric characteristics and density. It is usually of nearly uniform size and usually large enough to require individual placement. In normal cases it is used as primary wave protection and is placed in thicknesses of at least two units.|
|Armor||A coarse layer of gravel or cobble that develops on a streambed through winnowing away of fines.||Coastal Engineering|
The formation of a resistant layer of relatively large particles resulting from removal of finer particles by erosion.
|Aroclor||Aroclor is the registered trademark for a group of polychlorinated biphenyls that were manufactured by the Monsanto Company prior to 1976. Aroclors are assigned specific 4-digit reference numbers dependent upon molecular type and degree of substitution of the biphenyl ring hydrogen atoms by chlorine atoms. The first two digits of a numbered aroclor represent the molecular type, and the last two digits represent the percentage weight of the hydrogen-substituted chlorine.||Coastal Engineering|
|Artificial nourishment||The process of replenishing a beach with material (usually sand) obtained from another location.||Coastal Engineering|
Artificial substrate is a device that purposely is placed in a stream or lake for colonization of organisms. The artificial substrate simplifies the community structure by standardizing the oubstrate from which each sample is collected. Examples of artificial substrates are basket oamplers (made of wire cages filled with clean streamside rocks) and multiplate samplers (made of hardboard) for benthic organism collection, and plexiglass strips for periphyton collection.
(See also “Substrate”)
|As built||See constructed dimensions.||Coastal Engineering|
|Ash content||ASTM D 653) The percentage by dry weight of material remaining after an oven dry organic soil or peat is burned by a prescribed method.||Coastal Engineering|
Ash mass is the mass or amount of residue present after the residue from a dry-mass determination has been ashed in a muffle furnace at a temperature of 500 °C for 1 hour. Ash mass of zooplankton and phytoplankton is expressed in grams per cubic meter (g/m3), and periphyton and benthic
organisms in grams per square meter (g/m2). (See also “Biomass” and “Dry mass”)
Aspect is the direction toward which a slope faces with respect to the compass.
|Assimilation||The incorporation (or conversion) of nutrients and contaminants into the ecosystem.||Coastal Engineering|
|Astres fictifs||Fictitious celestial bodies which are assumed to move in the celestial equator at uniform rates corresponding to the speeds of the several harmonic constituents of the tide producing force. Each astre fictif crosses the meridian at a time corresponding to the maximum of the constituent that it represents.||Coastal Engineering|
|Astronomical day||See astronomical time.||Coastal Engineering|
|Astronomical tide||The tidal levels and character which would result from gravitational effects, e.g. of the Earth, Sun and Moon, without any atmospheric influences.||Coastal Engineering|
|Astronomical time||Time formerly used in astronomical calculations in which the day began at noon rather than midnight. The astronomical day commenced at noon of the civil day of the same date. The hours of the day were numbered consecutively from zero (noon) to 23 (11 a.m. of the following morning). Up to the close of the year 1924, astronomical time was in general use in nautical almanacs. Beginning with the year 1925, the American Ephemeris and Nautical Almanac and similar publications of their countries abandoned the astronomical time and adopted Greenwich civil (mean) time for the data given in their tables.||Coastal Engineering|
|Atmospheric (Barometric) Pressure||Measure of the pressure of the earth's atmosphere per unit area. It is 760 mm Hg at sea level and decreases with increasing elevation.||Coastal Engineering|
|Atoll||A ring-shaped coral REEF, often carrying low sand islands, enclosing a shallow LAGOON. The reef is surrounded by deep water of the open sea.||Coastal Engineering|
|Attainment||Meeting the Biocriteria standards for the designated aquatic life use.||Coastal Engineering|
|Attendant plant||All dredging equipment, excluding the dredge vessel itself, placed upon location to accomplish the dredging work. Such things as derrick barges, pipe barges, quarterboats, pipe, earthmoving equipment and tenders are included in this term.||Coastal Engineering|
1. A lessening of the amplitude of a wave with distance from the origin.
2. The decrease of water-particle motion with increasing depth. Particle motion resulting from surface oscillatory waves attenuates rapidly with depth, and practically disappears at a depth equal to a surface wavelength.
|Attenuator||Device which suppresses transmit signal so electronic distance measuring equipment can work close to the transmitter.||Coastal Engineering|
|Atterberg consistency limits||See Atterberg limits.||Coastal Engineering|
|Atterberg limits tests||Standardized laboratory tests for determining the water contents corresponding to the Atterberg limits. Standard test procedures are given in ASTM D4318. (See also Atterberg limits.)||Coastal Engineering|
|Atterberg limits||The water contents corresponding to the transition in clay-water mixtures from (a) the liquid to the plastic state (liquid limit), (b) the plastic to the semi-solid state (plastic limit), and (c) the semi-solid to the solid state (shrinkage limit). (See also Atterberg limits tests, liquid limit, plastic limit, plasticity index.)||Coastal Engineering|
|Audit||The independent appraisal activity within the Army for the review of financial, accounting, and related operations as a basis for protective and constructive service to management at all levels.||Coastal Engineering|
|Aufwuchs||The community of algae and other microorganisms that attach to surfaces such as rocks, twigs, and aquatic plants; essentially the same as "periphyton" that means "attached algae."||Coastal Engineering|
|Auger head dredge||See dredge, hydraulic, pipeline, cutterhead, auger head.||Coastal Engineering|
|Augmenting factor||A factor used in connection with the harmonic analysis of tides or tidal currents to allow for the fact that the tabulated hourly heights or speeds used in the summation for any constituent, other than S, do not in general occur on the exact constituent hours to which they are assigned, but may differ from the same by as much as a half hour.||Coastal Engineering|
|Authorized dimensions||(ER 1130-2-307) Length, width, and depth dimensions of a navigation project as specified in the authorizing document.||Coastal Engineering|
|Autochthonous||A term applied to shelves on which older shelf sediments are primarily being reworked by modern shelf processes.||Coastal Engineering|
|Autocorrelation coefficient||Measure of the autocorrelation between pairs of a series given by their covariance divided by the variance of the series. (DST)||Coastal Engineering|
|Autogenous volume change||Change in volume produced by continued hydration of cement exclusive of effects of external forces or change of water content or temperature (ACI 116R-85).||Coastal Engineering|
|(EM 1110-2-1003) Any system which combines positional and depth measurements into a single database, including associated guidance and tracking.||Coastal Engineering|
|Automatic tide gage||An instrument that automatically registers the rise and fall of the tide. In some instruments, the registration is accomplished by printing the heights at regular intervals, in others by a continuous graph in which the height of the tide is represented by the ordinates of the curve and the corresponding time by the abscissae.||Coastal Engineering|
A condition in which oxygen production by plants exceeds respiration by plants and animals. Sunlight and inorganic compounds are the primary energy source.
|Auxiliary ladder||Additional frame installed between the upper tumbler and the pivot at the base of the ladder.||Coastal Engineering|
|Average annual flow||The rate at which water flows through a channel, determined by averaging daily measurements of the flow during one entire year.||Coastal Engineering|
|Average||In quality assurance, a measure of central value which usually refers to the arithmetic mean obtained by dividing the sum of n terms by n.||Coastal Engineering|
|Avian habitat||(EM 1110-2-5026) Any area that meets all or part of the life requirements of birds, a very large and wide-ranging group of species with a variety of habitat requirements.||Coastal Engineering|
1. Rapid EROSION of the shore land by waves during a storm.
2. A sudden cutting off of land by flood, currents or change in course of a body of water.
|Awash||Situated so that the top is intermittently washed by waves or tidal action. Condition of being exposed or just bare at any stage of the tide between high water and chart datum.||Coastal Engineering|
|Axial jet||A flow pattern characteristic of hypopycnal inflow, in which the inflowing water spreads as a cone with a apical angle.||Coastal Engineering|
|Axial thrust||The result of two opposing forces at the pump; the change in momentum of the mixture entering the impeller which forces it backwards and the discharge from the impeller which forces it forward.||Coastal Engineering|
|Azimuth||Azimuth of a body is the arc of the horizon intercepted between the north or south point and the foot of the vertical circle passing through the body. It is reckoned in degrees from either the north or south point clockwise entirely around the horizon. Azimuth of a current is the direction toward which it is flowing, and is usually reckoned from the north point....||Coastal Engineering|
back to top
Pertaining to the lagoon-marsh-tidal creek complex in the lee of a coastal barrier island, barrier spit, or baymouth barrier
A heavy steel plate bolted to the inside surface of the back door of the pump casing in order to reduce wear on the pump shell.
Circular ring to which the rear ends of the cutter blades are attached.
Surrounding water not in the immediate vicinity of the dredging operation.
The seaward return of the water following the uprush of the waves. For any given tide stage the point of farthest return seaward of the backrush is known as the Limit of backrush or limit backwash.
Nuclear in situ density gauge based on the backscattering principle, the radiation is backscattered and detected, as opposed to the transmission principle, in which the transmissance of the radiation-energy is measured.
That zone of the shore or beach lying between the foreshore and the coastline comprising the BERM or BERMS and acted upon by waves only during severe storms, especially when combined with exceptionally high water. See also BACKBEACH. Synonym : Backbeach
|Backwash ripples||Low amplitude ripple marks formed on fine sand beaches by the Backwash of the waves.||Coastal Engineering|
Water or waves thrown back by an obstruction such as a ship, BREAKWATER, or cliff. See also BACKRUSH.
Synonym : Backrush
|Backwater curve||The longitudinal profile of the water surface in an open channel where the depth of flow has been increased by an obstruction as a weir or a dam across the channel, by increase in channel roughness, by decrease in channel width or by a decrease of the bed gradient.||Coastal Engineering|
|Backwater||Condition in which the water surface elevation is raised by downstream flow impediments.||Coastal Engineering|
|Bacteria||Bacteria are microscopic unicellular organisms, typically spherical, rodlike, or spiral and threadlike in shape, often clumped into colonies. Some bacteria cause disease, whereas others perform an essential role in nature in the recycling of materials; for example, by decomposing organic matter into a form available for reuse by plants.||Coastal Engineering|
|Baffle plate||A device placed at the end of the discharge pipe to distribute the outflow of dredged material over a larger area in the disposal facility and thereby minimize undesirable effects of direct impact(erosion).||Coastal Engineering|
|Baffle||A plate, wall, screen, or other device to deflect or impede flow.||Coastal Engineering|
A. As in dredge equipment, heavy duty hose used for connecting sections of rigid dredge pipe. Also referred to as a sleeve.
B. As in geotextiles, a large tube, that when filled with soil, can be used as a retaining dike.
|Ball check||In calibration, method by which echo sounders are independently calibrated using a ball suspended below the vessel.||Coastal Engineering|
|Ball joints||Spherically-designed flexible steel joints used to join sections of pipeline.||Coastal Engineering|
|Balling||Material forming into balls as it passes through the pipeline. (See also clay balling)||Coastal Engineering|
|Banded pipe||See pipe.||Coastal Engineering|
|Bandwidth||The range of frequencies in a signal.||Coastal Engineering|
|Bank migration||Lateral or horizontal movement of the banks of a streamcourse.||Coastal Engineering|
1. The rising ground bordering a lake, river, or sea; or of a river or channel, for which it is designated as right or left as the observer is facing downstream.
2. An elevation of the sea floor or large area, located on a continental (or island) shelf and over which the depth is relatively shallow but sufficient for safe surface navigation (e.g., Georges Bank); a group of shoals.
3. In its secondary sense, used only with a qualifying word such as "sandbank," "gravelbank," or "spoil bank," a shallow area consisting of shifting forms of silt, sand, mud, and gravel.
|Bankfull discharge||The flow that over time maintains the form of the channel by transporting the majority of the sediment load. For the purpose of this glossary, it is synonymous with effective and dominant discharge.||Coastal Engineering|
|Bankfull Stage||Bankfull stage, as used in this report, is the stage at which a stream first overflows its natural banks formed by floods with 1- to 3-year recurrence intervals.||Coastal Engineering|
|Bar check||In calibration,(EM 1110-2-1003) method by which echo sounders are independently calibrated with a doubly suspended reference bar.||Coastal Engineering|
|Bar, as in dredging|
Long steel beam, pulled along channel bottom to level shoals; (as in hydrographic surveying)- a steel beam that, when lowered beneath the fathometer transducer, is used to calibrate the transducer. (See also shoal.)
Synonym : Shoal
A submerged or emerged embankment of sand, gravel, or other unconsolidated material built on the sea floor in shallow water by waves and currents. See BAYMOUTH BAR, CUSPATE BAR.
Synonyms : Baymouth Bar, Cuspate Bar
An unpowered, flat bottomed vessel used mainly for transporting freight. Also known as a scow.
a. derrick, a barge which supports a derrick (from "a" frame to large rotatable boom), which is propelled by a dredge tender and is used to lift heavy objects such as the dredge's anchors, sunken or damaged pontoons, lifting & replacing spuds, and loading & unloading pipe.
b. fuel, a barge used for transporting fuel for the dredge & attendant plant.
d. mooring, a barge used as a fixed object to which other vessels are tied.
e. pipe, a barge used for transporting and storing pipe for the dredging operation.
f. water, a barge used for transporting water to be utilized by a steam driven dredge.
|Baroclinic||When isobaric surfaces of a fluid are not parallel with density surfaces.||Coastal Engineering|
|Barotropic||When isobaric surfaces of a fluid are parallel with density surfaces.||Coastal Engineering|
A bar essentially parallel to the shore, the crest of which is above normal high water level. Also called offshore barrier and BARRIER ISLAND.
Synonyms : Offshore Barrier, Barrier Island
|Barrier flat||The flat area, often marshy and populated with low vegetation, on the bay or lagoon side of a barrier island.||Coastal Engineering|
|Barrier island||A detached portion of a barrier beach between two inlets. It commonly has DUNES, vegetated areas, and swampy terranes (see BARRIER FLAT) extending from the beach into the lagoon. Example: Outer Banks, North Carolina||Coastal Engineering|
|Barrier lagoon||A bay roughly parallel to the coast and separated from the open ocean by barrier islands. Also, the body of water encircled by coral islands and REEFS, in which case it may be called an ATOLL lagoon.||Coastal Engineering|
|Barrier reef||A coral REEF parallel to and separated from the coast by a lagoon that is too deep for coral growth. Generally, barrier reefs follow the coasts for long distances and are cut through at irregular intervals by channels or passes. Example :Great Barrier Reef, Queensland, Australia.||Coastal Engineering|
|Barrier spit||Similar to a BARRIER ISLAND, but connected to the mainland.||Coastal Engineering|
|Barriers, coastal||Elongated, shore-parallel, usually sandy features that parallel coasts in many places and are separated from the mainland by bodies of water of various sizes, and/or salt marshes, lagoons, mud, or sand flats, and tidal creeks.||Coastal Engineering|
|Basalt||A dark gray to black dense fine-grained igneous rock.||Coastal Engineering|
Base discharge (for peak discharge) is a discharge value, determined for selected stations, above which peak discharge data are published. The base discharge at each station is selected so that an average of about three peak flows per year will be published. (See also “Peak flow”)
Synonym : Peak Flow
|Base Flow||Base flow is sustained flow of a stream in the absence of direct runoff. It includes natural and human-induced streamflows. Natural base flow is sustained largely by ground-water discharge.||Coastal Engineering|
|Base line||Multiple definitions, surveying, regulatory) Regulatory - (USACE and EPA. A Framework...) belt of the seas measured from he line of ordinary low water along that portion of the coast that is in direct contact with the open sea and the line marking the seaward limit of inland waters.||Coastal Engineering|
|Base||A substance which accepts protons (H+) and has a pH greater than 7 on a scale of 0-14; also referred to as an alkaline substance.||Coastal Engineering|
|Baseflow recession||The declining rate of discharge of a stream fed only by baseflow for an extended period. Typically, a baseflow recession will be exponential.||Coastal Engineering|
|Baseflow||The part of stream discharge that originates from groundwater seeping into the stream.||Coastal Engineering|
|Baseline boat||(EM 1110-2-1003) An anchored boat used to extend an offshore baseline for tag line surveys.||Coastal Engineering|
|Baseline||(EM 1110-2-1003) The primary reference line defining a construction coordinate system.||Coastal Engineering|
|Basic survey (hydrographic)||A comprehensive and complete hydrographic survey adequate to supersede all prior hydrographic surveys covering the common area and to verify or discredit/disprove the existence of all charted or reported features.||Coastal Engineering|
|Basin, boat||A naturally or artificially enclosed or nearly enclosed harbor area for small craft.||Coastal Engineering|
|Basin||A depressed area with no surface outlet, such as a lake basin or an enclosed sea.||Coastal Engineering|
|Bastion||A massive groin, or projecting section of seawall normally constructed with its crest above water level.||Coastal Engineering|
In quality assurance, a unit or subdivision of a lot, or block.
|Bathtub||As in dredged material placement, a type of re-usable dredged material placement area used on the Upper Mississippi River. Historical dredged material placement areas adjacent to the river are "dished" out using a hydraulic dredged to form a large confined disposal facility. (See also confined disposal facility.)||Coastal Engineering|
|Bathymetric chart||A topographic map of the bed of the ocean, with depths indicated by contours (isobaths) drawn at regular intervals.||Coastal Engineering|
The measurement of water depths in oceans, seas, and lakes; also information derived from such measurements.
|Bay barrier||A term signifying a spit that has grown entirely across the mouth of a bay so that the bay is no longer connected to the main body of water. See: barrier beach.||Coastal Engineering|
|Bay||A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove. See also BIGHT, EMBAYMENT.||Coastal Engineering|
|Baymouth bar||A bar extending partly or entirely across the mouth of a bay.||Coastal Engineering|
A minor sluggish waterway or estuarial creek, tributary to, or connecting, other streams or bodies of water, whose course is usually through lowlands or swamps. Sometimes called SLOUGH. Term is commonly used in the southern United States.
|Beach accretion||See ACCRETION.||Coastal Engineering|
A nearly horizontal part of the beach or backshore formed by the deposit of material by wave action. Some beaches have no berms, others have one or several.
|Beach crest||The point representing the limit of normal HIGH TIDE wave run-up (see BERM CREST)||Coastal Engineering|
|Beach cusp||See CUSP.||Coastal Engineering|
|Beach cycle||The periodic retreat and outbuilding of a beach under the influence of tides and waves; cutting back occurs during periods of spring tides and of high waves produced by winter storms; building out occurs during periods of neap tides and of low waves characteristic of summer.||Coastal Engineering|
|Beach erosion||The carrying away of beach materials by wave action, tidal currents, littoral currents, or wind.||Coastal Engineering|
The section of the beach normally exposed to the action of the wave uprush. The FORESHORE of a BEACH.
(Not synonymous with SHOREFACE.)
|Beach fill||Material placed on a beach to renourish eroding shores, usually pumped by dredge but sometimes delivered by trucks.||Coastal Engineering|
|Beach head||The cliff, dune or sea wall looming above the land ward limit of the active beach.||Coastal Engineering|
|Beach material||Granular sediments, usually sand or shingle moved by the sea.||Coastal Engineering|
|Beach nourishment surveys|
(EM 1110-2-1003) Surveys of coastal erosion control projects that involve combined topographic and hydrographic surveying procedures.
(33 CFR Part 335.7) Beach restoration or augmentation using clean dredged or fill sand. Dredged sand is usually hydraulically pumped and placed directly onto an eroded beach or placed in the littoral transport system. When the sand is dredged in combination with constructing, improving, or maintaining a navigation project, beach nourishment is a form of beneficial use of dredged material.
(See also beneficial use; hydraulic dredged material placement; nearshore feeder berms, beach fill)
A continuous and level or undulating area formed by closely spaced successive embankments of wave-deposited beach material added more or less uniformly to a prograding shoreline, such as to a growing compound spit or to a cuspate foreland.
|Beach plan shape||The shape of the beach in plan; usually shown as a contour line, combination of contour lines or recognizable features such as beach crest and/or the still water line.||Coastal Engineering|
|Beach profile||A cross-section taken perpendicular to a given beach contour; the profile may include the face of a dune or sea wall, extend over the backshore, across the foreshore, and seaward underwater into the NEARSHORE zone.||Coastal Engineering|
The sinuous shape commonly displayed on sandy shorelines where the wavelength is typically in tens of meters and the amplitude is up to 5 meters. Syn: rhythmic topography.
|Beach ridge||See RIDGE, BEACH.||Coastal Engineering|
|Beach scarp||See SCARP, BEACH.||Coastal Engineering|
|Beach width||The horizontal dimension of the beach measured normal to the shoreline and landward of the higher-high tide line (on oceanic coasts) or from the still water level (on lake coasts).||Coastal Engineering|
|Beach||The zone of unconsolidated material that extends landward from the low water line to the place where there is marked change in material or physiographic form, or to the line of permanent vegetation (usually the effective limit of storm waves). The seaward limit of a beach--unless otherwise specified--is the mean low water line. A beach includes foreshore and backshore. See also SHORE, SUSTAINABLE BEACH, and SELF-SUSTAINING BEACH, and TIDELANDS.||Coastal Engineering|
1. A fixed aid to navigation.
2. Anything serving as a signal or conspicuous indication, wither for guidance or warning. (See also topmark)
1. The extreme width of a vessel.
2. The widest part of a vessel.
|Bearing packing||Material compressed inside a pump stuffing box or the like to prevent leakage around a moving shaft and its associated bearings.||Coastal Engineering|
|Bearing||The horizontal direction of a line of sight between two objects on the surface of the earth.||Coastal Engineering|
|Beaufort scale||Classification of the force of the winds in accordance with a scale established by Rear-Admiral, Sir Francis Beaufort in which the range of intensity varies in integers from 0 to 12, with a description of the state and behavior of a "well conditioned man-of-war."||Coastal Engineering|
(Huston. Hydraulic Dredging Principles...)
The fitting on a block to which the dead end of the fall is attached.
Any deviation from a flat bed that is readily detectable by eye and higher than the largest sediment size present in the parent bed material; generated on the bed of an alluvial channel by the flow.
(ISO 8384) Vessel employed to level the bed at the dredging site, so that loosened, suspended material is taken away by the current or settles in deeper areas. (See also bar)
|Bed load discharge||The quantity of bed load passing a cross section in a unit of time, i.e. the rate. Usually presented in units of tons per day. May be measured or computed. See Bed Load.||Coastal Engineering|
|Bed load sampler||A device for sampling the bed load.||Coastal Engineering|
|Bed load||Sediment transport mode in which individual particles either roll or slide along the bed as a shallow, mobile layer a few particle diameters deep, the part of the load that is not continuously in suspension.||Coastal Engineering|
|Bed material sampler||A device for sampling bed material.||Coastal Engineering|
is the sediment mixture of which a streambed, lake, pond, reservoir, or estuary bottom is composed.
(See also “Bedload” and “Sediment”)
|See Sorting.||Coastal Engineering|
|Bed protection||A (rock) structure on the bed in order to protect the underlying bed against erosion due to current and/or wave action.||Coastal Engineering|
|Bed rock||A general term for the rock, usually solid, that underlies soil or other unconsolidated, superficial material.||Coastal Engineering|
|Bed roughness||A measure of the irregularity of the streambed as it contributes to flow resistance. Commonly expressed as a Manning's "n" value.||Coastal Engineering|
|Bed shear stress||The way in which waves (or currents) transfer energy to the sea bed.||Coastal Engineering|
|Bed||The bottom of a watercourse, or any body of water.||Coastal Engineering|
|Bedding plane||A surface parallel to the surface of deposition, which may or may not have a physical expression. The original attitude of a bedding plane should not be assumed to have been horizontal.||Coastal Engineering|
|Bedding||(ASTM D 653) Applies to rocks resulting from consolidation of sediments and exhibiting surfaces of separation (bedding planes) between layers of the same or different materials, that is, shale, siltstone, sandstone, limestone, etc.||Coastal Engineering|
|Bedforms||Ripples, waves, dunes, and related forms that develop under various flow conditions on the beds of alluvial streams with significant bed-load transport.||Coastal Engineering|
Bedload discharge (tons per day) is the rate of sediment moving as bedload, reported as dry weight, that passes through a cross section in a given time. NOTE: Bedload discharge values in this report may include a component of the suspended-sediment discharge. A correction may be necessary when computing the total sediment discharge by summing the bedload discharge and the suspendedsediment
discharge. (See also “Bedload,” “Dry weight,” “Sediment,” and “Suspended-sediment discharge”)
|Bedload transport||Quantity of sediment transported along the bottom of a river; contrast suspended load transport.||Coastal Engineering|
Bedload is material in transport that primarily is supported by the streambed. In this report, bedload is considered to consist of particles in transit from the bed to the top of the bedload sampler nozzle (an elevation ranging from 0.25 to
0.5 foot). These particles are retained in the bedload sampler. A sample collected with a pressure-differential bedload sampler also may contain a component of the suspended load.
|Bedrock||The solid rock that underlies gravel, soil, and other superficial material. Bedrock may be exposed at the surface (an outcrop) or it may br buried under a few centimeters to thousands of meters of unconsolidated material.||Coastal Engineering|
|Before-dredging survey||(EM 1110-2-1003) Survey performed immediately in advance of a dredging operation for initial payment reference grade. (See also pre-dredge hydrographic survey.)||Coastal Engineering|
|Belay||(Huston. Hydraulic Dredging Principles...) The act of securing a line to a cleat, set of bits, or any other fixed point. In connection with an order, or announcement, it expresses the idea of "to disregard", as "belay that last order."||Coastal Engineering|
|Bell mouth||The open end of the "bell" half of a pipeline ball joint.||Coastal Engineering|
|Belly anchor||See anchor.||Coastal Engineering|
|Belly||Term used to describe the limber line when flow causes line to bow or sag.||Coastal Engineering|
|Bench mark, tidal||A bench mark whose elevation has been determined with respect to MEAN SEA LEVEL at a nearby tide GAUGE; the tidal bench mark is used as reference for that tide gauge.||Coastal Engineering|
|Bench mark||A permanently fixed point of known elevation. A primary bench mark is one close to a tide station to which the tide staff and tidal datum originally are referenced.||Coastal Engineering|
1. A level or gently sloping erosion plane inclined seaward.
2. A nearly horizontal area at about the level of maximum high water on the sea side of a dike.
|Beneficial occupancy date, bod||The beneficial occupancy date is the date on which beneficial occupancy is granted to the agency requiring use of the facility following construction. By mutual agreement, the occupying agency will allow the construction agency access as required to complete remaining items of construction pursuant to the construction contract.||Coastal Engineering|
|Beneficial occupancy||Occupancy of an uncompleted building, structure, or facility for its intended purpose under circumstances which are advantageous to the occupant and which produce relatively little interference with the builder in completing construction. Prior to occupancy by the using service, a written agreement among the contractor, construction agency, and the using service is provided listing deficiencies, remaining work, and other conditions of occupancy that must be consummated. Beneficial occupancy may be a contract requirement.||Coastal Engineering|
|Beneficial use of dredged material||Placement or use of dredged material for some productive purpose. Examples : BEACH FILL or NEARSHORE BERM construction.||Coastal Engineering|
|Beneficial uses||Placement or use of dredged material for some productive purpose. May involve either the use of the dredged material or the placement site as the integral component of the use.||Coastal Engineering|
|Benefits||The asset value of a scheme, usually measured in terms of the cost of damages avoided by the scheme, or the valuation of perceived amenity or environmental improvements.||Coastal Engineering|
|Benthic macroinvertebrate||Backboneless aquatic animals that dwell on or in the bottom sediments of a stream channel that are large enough to be seem by the unaided eye.||Coastal Engineering|
Benthic organisms are the group of organisms inhabiting the bottom of an aquatic environment. They include a number of types of organisms, such as bacteria, fungi, insect larvae and nymphs, snails, clams, and crayfish. They are
useful as indicators of water quality.
|Benthic zone||Lake bottom sediment.||Coastal Engineering|
|Benthic||Of, pertaining to, or related to the bottom of a stream or other body of water.||Coastal Engineering|
|Benthos||Those animals who live on the sediments of the sea floor, including both mobile and non-mobile forms.||Coastal Engineering|
|Berm breakwater||Rubble mound structure with horizontal berm of armor stones at about sea level, which is allowed to be (re)shaped by the waves.||Coastal Engineering|
|Berm crest||The seaward limit of a BERM. Also called BERM EDGE.||Coastal Engineering|
|Berm, beach||See BEACH BERM.||Coastal Engineering|
1. On a beach a nearly horizontal plateau on the beach face or backshore, formed by the deposition of beach material by wave action or by means of a mechanical plant as part of a beach renourishment scheme. Some natural beaches have no berm, others have several.
2. On a structure: a nearly horizontal area, often built to support or key-in an armor layer.
|Bias||A systematic error introduced into sampling or testing by selecting or encouraging one outcome or answer over others. Bias can be introduced by setting variables or factors which would result in one outcome.||Coastal Engineering|
|Bicarbonate Buffering Equilibrium Equation||See Carbonate Buffering System.||Coastal Engineering|
|Bicarbonate||The anion HCO3.||Coastal Engineering|
|Bifurcation||The separation or branching of a stream into two parts (the opposite of a confluence).||Coastal Engineering|
|bight||A bend in a coastline forming an open BAY. A BAY formed by such a bend.||Coastal Engineering|
|Bilge pump||Used to remove collected liquid in the vessel bilge.||Coastal Engineering|
|Bilge||(Huston. Hydraulic Dredging Principles...) Bottom compartment of a dredge below all equipment where all liquid wastes from the dredge are collected.||Coastal Engineering|
|Bin measurement||(EM 1110-2-1003) A method of estimating work accomplished where the quantity measurement of material in a hopper or scow is used for payment purposes.||Coastal Engineering|
|Bin sounding||After loading, the elevation of the settled solids in the hopper(s) are measured by taking a sufficient number of vertical measurements (abitats) from a fixed datum throughout the bins so that an average is representative of the whole.||Coastal Engineering|
|Bin water volume||The volume of water occurring in hopper bins after pumpout operations are completed.||Coastal Engineering|
|Bin, as in dredging||The large holding area in a hopper dredge/barge into which dredged material is placed for transport.||Coastal Engineering|
|Bioaccumulation||(Dredged Material Testing Manual) The accumulation of contaminants in the tissues of organisms through any route, including respiration, ingestion, or direct contact with contaminated water, sediment, or dredged material. Regulatory - The regulations require that bioaccumulation be considered as part of the environmental evaluation of dredged material proposed for open water dumping. This consideration involves predicting whether there will be a cause-and-effect relationship between an animal's presence in the area influenced by the dredged material and an environmentally important elevation of its tissue content or body burden of contaminants above that in similar animals not influenced by the disposal of the dredged material.||Coastal Engineering|
|Bioassay||A bioassay is an assay using a biological system. It involves exposing an organism to a test material and determining a response. There are two major types of bioassays differentiated by response - toxicity tests which measure an effect (e.g., acute toxicity, sublethal/chronic toxicity) and bioaccumulation tests which measure a phenomenon (e.g., the uptake of contaminants into tissues).||Coastal Engineering|
|Bioavailable||Can be taken up by organisms, i.e., from water, sediment, suspended particles, food.||Coastal Engineering|
|Biochemical oxygen demand (BOD)||Biochemical oxygen demand (BOD) is a measure of the quantity of dissolved oxygen, in milligrams per liter, necessary for the decomposition of organic matter by microorganisms, such as bacteria.||Coastal Engineering|
|Biochemical oxygen demand, bod|
(EM 1110-2-5206) The amount of oxygen required during the aerobic decomposition of organic matter in a body of water. High BOD usually indicates large amounts of organic material.
|Bioconcentration||Bioaccumulation of a substance in tissues to levels higher than in the source. Note that, in some cases, bioconcentration is used interchangeably with bioaccumulation, referring to the amount of a substance accumulated from water.||Coastal Engineering|
|Biocriteria||(or Biological Criteria) - Water quality criteria based on measurable characteristics or narrative descriptions of aquatic communities.||Coastal Engineering|
Systematic determination of the effects on aquatic life, including accumulation of pollutants in tissue, in receiving waters as a result of the discharge of pollutants
(a) by techniques and procedures, including sampling of organisms representative of appropriate levels of the food chain appropriate to the volume and the physical, chemical, and biological characteristics of the effluent, and
(b) at appropriate frequencies and locations.
|Biological oxygen demand (BOD)||The amount of oxygen, typically measured in mg/l, removed from an aquatic environment by the life processes of organisms.||Coastal Engineering|
|Biomagnification||Bioconcentration of the food chain, e.g., the route of accumulation is solely through food.|||
|Biomanipulation||Reducing algal blooms by altering the fish community to reduce predation on certain zooplankton (cladocerans such as daphnia) that can most efficiently graze on algae.||Coastal Engineering|
|Biomass Pigment Ratio||Biomass pigment ratio is an indicator of the total proportion of periphyton that are autotrophic (plants). This also is called the Autotrophic Index.||Coastal Engineering|
Biomass is the amount of living matter present at any given
time, expressed as mass per unit area or volume of habitat.
|Biotic||Referring to a live organism.||Coastal Engineering|
|Bioturbation||The disturbance of sediment bedding by the activities of burrowing organisms.||Coastal Engineering|
|Birdfoot delta||A river DELTA formed by many levee-bordered DISTRIBUTARIES extending seaward and resembling in plan the outstretched claws of a bird. Example : Mississippi River delta.||Coastal Engineering|
|Birgean Heat Budget||See Heat Budget.||Coastal Engineering|
|Bit, drill||See drill bit.||Coastal Engineering|
|Blanket (foundation or bedding)||A layer or layers of graded fine stones underlying a BREAKWATER, GROIN or rock embankment to prevent the natural bed material from being washed away.||Coastal Engineering|
|Blanking||In hydrograph survey, the sensitivity setting of an electronic positioning system that sets a minimum signal that will be accepted by the system.||Coastal Engineering|
|Blastability||(ASTM D 653) Index value of the resistance of a rock formation to blasting.||Coastal Engineering|
|Bleeder pipe||See pipe.||Coastal Engineering|
|Block, block of work||In quality assurance-See lot.||Coastal Engineering|
|Block||One or more sheaves fitted into a frame called a shell. Two blocks reeved with a wire/line/rope is called a block and tackle.||Coastal Engineering|
|Blown sands||See EOLIAN SANDS.||Coastal Engineering|
|Blowout||A depression on the land surface caused by wind erosion.||Coastal Engineering|
|Blow-up||An expression commonly used either to refer to the act of enlarging a given document or to the actual enlarged version of a given document.||Coastal Engineering|
|Blue-green algae (Cyanophyta)|
Blue-green algae (Cyanophyta) are a group of phytoplankton and periphyton organisms with a blue pigment in addition to a green pigment called chlorophyll. Blue-green algae can cause nuisance water-quality conditions in lakes and slow-flowing rivers; however, they are found commonly in streams throughout the year. The abundance of blue-green algae in phytoplankton samples is expressed as the number of cells per milliliter (cells/mL) or biovolume in cubic micrometers per milliliter (µm3/mL).
The abundance of blue-green algae in periphyton samples is given in cells per square centimeter (cells/cm2) or biovolume per square centimeter (µm3/cm2).
|Bluff||A high, steep bank or cliff.||Coastal Engineering|
|Boat basin||A naturally or artificially enclosed or nearly enclosed harbor area for small craft.||Coastal Engineering|
|Boat grid||See careening grid.||Coastal Engineering|
|Boat sheet||Obsolete term. the work sheet used in the field for plotting the field observations of a hydrographic or wire drag survey. This work sheet is presently referred to as a "field sheet". (See also field sheet.)||Coastal Engineering|
|Bog||A wet, spongy, poorly drained area which is usually rich in very specialized plants, contains a high percentage of organic remnants and residues and frequently is associated with a spring, seepage area, or other subsurface water source. A bog sometimes represents the final stage of the natural processes of eutrophication by which lakes and other bodies of water are very slowly transformed into land areas.||Coastal Engineering|
|Boil||An upward flow of water in a sandy formation due to an unbalanced hydrostatic pressure resulting from a rise in a nearby stream, or from removing the overburden in making excavations.||Coastal Engineering|
|Bold coast||A prominent landmass that rises steeply from the sea.||Coastal Engineering|
|Bollard||Strong cylindrical upright on a pier around which the eye or bight of ship's mooring line is thrown.||Coastal Engineering|
|Bollards||Heavy post and chain fixtures used to exclude wheeled vehicles from protected areas.||Coastal Engineering|
|Bond strength||Resistance to separation of concrete or mortar and other contact surfaces.||Coastal Engineering|
|Bond stress||The force per unit area of contact between two bonded surfaces.||Coastal Engineering|
|Booby house||Small house located on last pontoon of dustpan dredge where a pipelineman controls the positioning of the pipeline through manipulation of the baffle plate.||Coastal Engineering|
|Boomer||A broad band high intensity seismic source used in geophysical investigations of subbottom materials. Also used for acoustic impedance data acquisition where deep penetration low resolution information is required.||Coastal Engineering|
|Booster pump||Additional pumps used in conjunction with pipeline disposal to increase the maximum transport distance between the dredging operation and the disposal area.||Coastal Engineering|
|Booster||See booster pump.||Coastal Engineering|
See tidal bore.
A very rapid rise of the tide in which the advancing water presents an abrupt front of considerable height. In shallow estuaries where the range of tide is large, the high water is propagated inward faster than the low water because of the greater depth at high water. If the high water overtakes the low water, an abrupt front is presented, with the high-water crest finally falling forward as the tide continues to advance. Also EAGER.
|Borehole geochemical probe||A device for monitoring water quality that is lowered into a well on a cable and can take direct readings of such parameters as pH, Eh, temperature, SP, and specific conductivity.||Coastal Engineering|
|Borehole geophysics||The general field of geophysics developed around the lowering of various probes into wells.||Coastal Engineering|
A hole advanced into the ground by means of a drilling rig.
|Borrow material||(EM 1110-2-5026) Soil or sediment taken from a site for use in structure construction, such as sandy sediment dredged and pumped to restore an eroded beach, or clay taken to build a levee or dike.||Coastal Engineering|
1. A hole created by excavating levee embankment material.
2. (EM 1110-2-5026) The term used to describe the site remaining after borrow material has been removed. In upland areas, the site frequently becomes a body of water. In marine areas, the site becomes a deep hole in a bay or near-shore area.
|Bottom (nature of)||The composition or character of the bed of an ocean or other body of water (e.g., clay, coral, gravel, mud, ooze, pebbles, rock, shell, shingle, hard, or soft).||Coastal Engineering|
|Bottom boundary layer||The lower portion of the water flow that experiences frictional retardation based on its proximity to the bed.||Coastal Engineering|
|Bottom characteristics||A designation used in hydrographic surveying and on nautical charts to describe the nature of bottom materials/sediments; i.e., to indicate the size/consistency, color and classification of bottom sediments. The expressions "bottom characteristics" and "bottom sample" are not to be used interchangeably; i.e., the placement of "bottom samples" on the chart would serve to hinder the effective use of the chart for navigation purposes.||Coastal Engineering|
|Bottom discharge opening||(ISO 8384) Opening in the bottom of the hull for disposal of the soil via either doors or valves.||Coastal Engineering|
|Bottom dump doors||Doors at the bottom of a hopper dredge or barge that allow disposal of hopper contents by simply opening at the disposal site.||Coastal Engineering|
|Bottom material||Bottom material (See “Bed material”)||Coastal Engineering|
|Bottom roughness||See manning n factor.||Coastal Engineering|
|Bottom sediments||Consolidated materials comprising true hard bottom underneath a water column. (See also sediment.)||Coastal Engineering|
|Bottom||The ground or bed under any body of water; the bottom of the sea.||Coastal Engineering|
(EM 1110-2-5206) Deciduous forests of dominant tree species which occur on soils that are moisture-saturated or inundated during a portion of the growing season. These forests are in serious decline due primarily to agricultural land clearing and flood control.
|Bottomset bed||Fine-grained material (usually silts and clays) slowly deposited on the bed of a quiescent body of water and which may in time be buried by foreset beds and topset beds.||Coastal Engineering|
|Bottomset||One of the horizontal or gently inclined sediment layers deposited in front of the advancing forest beds of a delta.||Coastal Engineering|
|Boulder clay||(ASTM D 653) A geological term used to designate glacial drift that has not been subjected to the sorting action of water and therefore contains particles from boulders to clay sizes.||Coastal Engineering|
|Boulder||A rounded rock more than 256 mm (10 inch) in diameter; larger than a cobblestone. See SOIL CLASSIFICATION.||Coastal Engineering|
Environmental conditions, e.g. waves, currents, drifts, etc. used as boundary input to physical or numerical models.
|Boundary current||A deep ocean current, especially along the western part of the oceans, characterized by sudden changes in temperature and salinity.||Coastal Engineering|
|Boundary effect||Consequence of dissimilarities between the model boundary conditions and the conditions occurring in the prototype at the location of the model boundaries.||Coastal Engineering|
|Boundary Roughness||The roughness of the bed and banks of a stream or river. The greater the roughness, the greater the frictional resistance to flows; and, hence, the greater the water surface elevation for any given discharge.||Coastal Engineering|
|Bourdon gage||A type of gage usually used on dredges to measure vacuum and pressure because of their ruggedness, reliability, and inherent accuracy.||Coastal Engineering|
|Bow line||See line.||Coastal Engineering|
|Bow thrusters||Ports located on both the port and starboard bow of hopper dredges through which water is thrusted perpendicular to the vessel axis to give greater maneuverability in turning the vessel.||Coastal Engineering|
|Bow||Forward-most portion of a vessel.||Coastal Engineering|
|Box gage||A tide GAUGE that is operated by a float in a long vertical box to which the tide is admitted through an opening in the bottom. In the original type of box gauge the float supported a graduated rod which rose and fell with the tide.||Coastal Engineering|
|Brackish||Slightly salty water.||Coastal Engineering|
|Braided channel||A stream that is characterized by random interconnected channels divided by islands or bars. Bars which divide the stream into separate channels at low flows are often submerged at high flow.||Coastal Engineering|
|Braided river||A river type with multiple channels separated by shoals, bars and islands.||Coastal Engineering|
|Brake horsepower||The power expended in forcing the material out of the discharge (water horsepower) plus the power required to turn the pump and supply all losses.||Coastal Engineering|
|Breach||A new opening in a narrow landmass, such as a barrier spit or a barrier island, that allows flow between water bodies on either side of the landmass.||Coastal Engineering|
1. Formation of a channel through a barrier spit or island by storm waves, tidal action, or river flow. Usually occurs after a greater than normal flow, such as during a hurricane.
2. Failure of a dike allowing flooding.
|breaker depth||The still-water depth at the point where a wave breaks. Also called BREAKING DEPTH.||Coastal Engineering|
Ratio of breaking wave height to DEEPWATER wave height.
|Breaker line||The axis along which a wave breaks as it approaches the shore. Syn: plunge line.||Coastal Engineering|
The zone within which waves approaching the coastline commence breaking, typically in water depths of between 5 and 10 meters for ocean coasts, but sometimes in shallower water.
A wave breaking on a shore, over a REEF, etc. Breakers may be classified into four types:
COLLAPSING--breaking occurs over lower half of wave, with minimal air pocket and usually no splash-up. Bubbles and foam present.
PLUNGING--crest curls over air pocket; breaking is usually with a crash. Smooth splash-up usually follows.
SPILLING--bubbles and turbulent water spill down front face of wave. The upper 25 percent of the front face may become vertical before breaking.
Breaking generally occurs over quite a distance.
SURGING--wave peaks up, but bottom rushes forward from under wave, and wave slides up beach face with little or no bubble production. Water surface remains almost plane except where ripples may be produced on the beachface during runback.
|Breaking||Reduction in wave energy and height in the surf zone due to limited water depth.||Coastal Engineering|
|Breakpoint bar||A longshore bar formed at the breakpoint of waves, where there is a sudden decrease of sand moving landward outside the breakpoint but where sand is moving seaward to this point.||Coastal Engineering|
|breakwater||A man-made structure protecting a shore area, harbor, anchorage, or basin from waves. A harbor work.||Coastal Engineering|
|Breast line||A mooring line leading at an angle of about 90 degrees from the fore - and aft-line of a vessel to the wharf.||Coastal Engineering|
(Huston. Hydraulic Dredging Principles...) To "breast in" is to heave the vessel sideways toward a wharf or other vessel.
|Breastwork||Vertically-faced or steeply inclined structure usually built with timber and parallel to the shoreline, at or near the beach crest, to resist erosion or mitigate against flooding.||Coastal Engineering|
|Bridge scour depth||The calculated depth at which the streambed and substrate will mobilize and be transported during channel forming flows. Used to determine the safe depth at which to place footings and stable keyways in streambeds that will not erode or be undermined.||Coastal Engineering|
|Bridge scour||Excessive erosion of the stream banks and bottom below a bridge as a result of the concentration and direction of streamflow.||Coastal Engineering|
|Bridge||A structure designed to carry traffic over a depression or other obstruction. The term refers to a lawful bridge over navigable waters of the Untied States, including approaches, fenders, and appurtenances thereto, which is used and operated for the purpose of carrying railroad traffic, or both railroad and highway traffic, or if a state, county or municipality, or other political subdivision is the owner or joint owner thereof, which is used and operated for the purpose of carrying highway traffic.||Coastal Engineering|
|Bubbler hydrostatic pressure sensors||Pressure sensors typically used to measure the draft of a vessel as function of hydrostatic pressure change.||Coastal Engineering|
|Bubbler tide gage||See gas purged pressure gage.||Coastal Engineering|
|Bubbler, slang term||See bubbler hydrostatic pressure sensors.||Coastal Engineering|
|Bucket ladder dredge||See dredge, mechanical, bucket ladder.||Coastal Engineering|
|Bucket wheel dredge||See dredge, hydraulic, pipeline, bucket wheel.||Coastal Engineering|
A parcel or strip of land that is designed and designated to permanently remain vegetated in an undisturbed and natural condition to protect an adjacent aquatic or wetland site from upland impacts, to provide habitat for wildlife and to afford limited public access.
A substance which tends to keep pH levels fairly constant when acids or bases are added.
|Buffering Capacity||Ability of a solution to resist changes in ph when acids or bases are added; the buffering capacity of natural waters is mostly due to dissolved carbonate rocks in the basin; equivalent to acid neutralizing capacity (anc). Typically considered to be exhausted.||Coastal Engineering|
|Bulk density||Identical to apparent specific gravity, Ga = soil density ÷ density of water. "Apparent" means that the basis of measurement is the total soil volume including voids, not just the individual soil particles.||Coastal Engineering|
|Bulk Electrical Conductivity||Bulk electrical conductivity is the combined electrical conductivity of all material within a doughnut-shaped volume surrounding an induction probe. Bulk conductivity is affected by different physical and chemical properties of the material including the dissolved-solids content of the pore water, and the lithology and porosity of the rock.||Coastal Engineering|
|Bulk factor||Relative change in volume at constant solid content.||Coastal Engineering|
|Bulk measure||Dredged material measurement in tons.||Coastal Engineering|
|Bulkhead||A structure or partition to retain or prevent sliding of the land. A secondary purpose is to protect the UPLAND against damage from wave action.||Coastal Engineering|
|Bulking factor||The ratio of the disturbed volume of a soil to the original, or in situ, volume of the same amount of soil material.||Coastal Engineering|
|Bulking||Change in volume, usually an increase, of a sediment due to disturbance or manipulation by dredging or other means.||Coastal Engineering|
|Bull nose||Substantial lip or protuberance at the top of the seaward face of a wall, to deflect waves seaward.||Coastal Engineering|
|Buoy||A float; especially a floating object moored to the bottom, to mark a channel, anchor, shoal rock, etc. Some common types include a nun or nut buoy is conical in shape; a can buoy is squat and cylindrical above water and conical below water; a spar buoy is a vertical, slender spar anchored at one end; a bell buoy, bearing a bell, runs mechanically or by the action of waves, usually marks shoals or rocks; a whistling buoy, similarly operated, marks shoals or channel entrances; a dan buoy carries a pole with a flag or light on it.||Coastal Engineering|
|The resultant of upward forces, exerted by the water on a submerged or floating body, equal to the weight of the water displaced by this body.||Coastal Engineering|
A short flood diversion channel constructed to bypass a natural stream reach or features of special interest such as wetlands. Bypass channels may be constructed to convey all flows or flood discharges only.
|Bypassing, sand||Hydraulic or mechanical movement of sand from the accreting updrift side to the eroding downdrift side of an inlet or harbor entrance. The hydraulic movement may include natural movement as well as movement caused by man.||Coastal Engineering|
1. Hydraulic or mechanical movement of sand from the accreting updrift side to the eroding downdrift side of an inlet or harbor entrance. The hydraulic movement may include natural movement as well as movement caused by man.
2. A term applied to sediment transport across areas of no deposition, as in the case where one particle size passes another that is being simultaneously transported, or continues in motion after the other has come to rest (e.g., the normal decrease in average particle size of sediments away from a source area).
back to top
The standard (Clear/Acquisition) GPS code - a sequence of 1023 pseudo-random, binary, biphase modulations on the GPS carrier at a chip rate of 1.023 MHz. Also known as the "civilian code."
|Caisson||Concrete box-type structure.||Coastal Engineering|
|Calcareous||Containing calcium carbonate (CaCO3), chiefly as the minerals calcite and aragonite. When applied to rock, it implies that as much as 50 percent of the rock is carbonate (e.g., calcareous sand)||Coastal Engineering|
1. Adjustment of a model’s parameters such as roughness or dispersion coefficients so that it reproduces observed prototype data to acceptable accuracy.
2. The process of refining the model representation of the hydrogeologic framework, hydraulic properties, and boundary conditions to achieve a desired degree of correspondence between the model simulations and observations of the groundwater flow system.
|California current||A North Pacific Ocean current setting southeastward along the west coast of the United States and Baja, California.||Coastal Engineering|
|California draghead||See drag head.||Coastal Engineering|
|Caliper log||A borehole log of the diameter of an uncased well.||Coastal Engineering|
|Callippic cycle||A period of four Metonic cycles equal to 76 Julian years, or 27,759 days. Devised by Callippus, a Greek astronomer, about 350 B.C., as a suggested improvement on the Metonic cycle for a period in which new and full Moon would recur on the same day of the year. Taking the length of the synodical month as 29.530588 days, there are 940 lunations in the Callippic cycle, with about 0.25 day remaining.||Coastal Engineering|
|Calm||The condition of the water surface when there is no WIND WAVES or SWELL.||Coastal Engineering|
|Calorie||A basic measure of energy where 1 calorie is equal to the total amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius.||Coastal Engineering|
|Camel||Floating structure used to space a vessel away from a dock to prevent interference between the two.||Coastal Engineering|
|Canadian Geodetic Vertical Datum 1928||Canadian Geodetic Vertical Datum 1928 is a geodetic datum derived from a general adjustment of Canada’s first order level network in 1928.||Coastal Engineering|
|Canal||An artificial watercourse cut through a land area for such uses as navigation and irrigation.||Coastal Engineering|
|Canyon||A relatively narrow, deep depression with steep slopes, the bottom of which grades continuously downward. May be underwater (submarine) or on land (SUBAERIAL).||Coastal Engineering|
|Cape||A land area jutting seaward from a continent or large island which prominently marks a change in, or interrupts notably, the coastal trend; a prominent feature. Examples : Cape Cod, Massachusetts; Cape Hatteras, North Carolina.||Coastal Engineering|
|Capillary Action||The action by which water is drawn around soil particles (or any other solid substance like a small bore tube) because there is a stronger attraction between the soil or solid particles and the water molecules themselves.||Coastal Engineering|
|Capillary forces||The forces which act on soil moisture in the unsaturated zone, caused by the molecular attraction between soil particles and water.||Coastal Engineering|
|Capillary wave||A wave whose velocity of propagation is controlled primarily by the surface tension of the liquid in which the wave is traveling. Water waves of length less than about 1 inch are considered capillary waves. Waves longer than 1 inch and shorter than 2 inches are in an indeterminate zone between capillary and gravity waves. See RIPPLE.||Coastal Engineering|
|Capital dredging||Dredging carried out to create new channels, etc., as distinct from maintenance dredging; also called new-work dredging. (See also new work dredging.)||Coastal Engineering|
|(DRP Tech Note 5-03, 2/91) The controlled, accurate placement of contaminated material at an open-water site, followed by a covering or cap of clean material to isolate contaminated sediment from the overlying aquatic environment. In this context, "contaminated" refers to material found to be unacceptable for unrestricted open-water placement because of potential contaminant effects, while the term "clean" refers to material found to be acceptable for such placement.||Coastal Engineering|
|Capstan||Any of various windlasses, rotated in a horizontal plane by hand or machinery, for winding in ropes, cables, etc.||Coastal Engineering|
Dredge superintendent who has the direct responsibility for the overall operation of an individual dredge plant. (See also master)
Synonym : Master
|Carbon Cycle||The circulation of carbon atoms through the earth's whole ecosystem.||Coastal Engineering|
|Carbon Dioxide||A gas which is colorless and odorless; when dissolved in water it becomes carbonic acid; CO2 is assimilated by plants for photosynthesis in the "dark" cycles of photosynthesis.||Coastal Engineering|
|Carbonate Buffering System||The most important buffer system in natural surface waters and wastewater treatment, consisting of a carbon dioxide, water, carbonic acid, Bicarbonate, and Carbonate ion equilibrium that resists changes in the water's pH. If acid (hydrogen ions) is added to this buffer solution, the equilibrium is shifted and carbonate ions combine with the hydrogen ions to form bicarbonate. Subsequently, the bicarbonate then combines with hydrogen ions to form carbonic acid, which can dissociate into carbon dioxide and water. Thus the system pH is unaltered (buffered) even though acid was introduced.||Coastal Engineering|
|Carbonate ion||The CO3-2 ion in the Carbonate Buffer System the collective term for the natural inorganic chemical compounds related to carbon dioxide that exists in natural waterways. Combined with one proton, it becomes Bicarbonate, HCO3- and with two protons, Carbonic Acid. The carbonate ion forms a solid precipitant when combined with dissolved ions of calcium or magnesium.||Coastal Engineering|
|Carbonate||Sediment formed by the organic or inorganic precipitation from aqueous solution of carbonates of calcium, magnesium, or iron.||Coastal Engineering|
|Careening grid||A timber structure in the intertidal zone serving as a support for vessels at low stages of the tide to permit work on the exposed portion of the vessel's hull.||Coastal Engineering|
|Carnivores||"Meat" eaters; organisms that eat other organisms.||Coastal Engineering|
|Carrier||A signal that can be varied from a known reference by modulation.||Coastal Engineering|
|Carrier-aided tracking||A signal processing strategy that uses the GPS carrier signal to achieve an exact lock on the pseudo random code. More accurate than standard approach.||Coastal Engineering|
|Cartography||The science and art of making maps.||Coastal Engineering|
|Catabatic wind||See katabatic wind.||Coastal Engineering|
|Catchment area||The area which drains naturally to a particular point on a river, thus contributing to its natural discharge.||Coastal Engineering|
|Catchment||Another term for Watershed commonly used in Canada and Europe.||Coastal Engineering|
|Cations||Positively charged ions.||Coastal Engineering|
|Causeway||A raised road across wet or marshy ground, or across water.||Coastal Engineering|
|Caustic||In refraction of waves, the name given to the curve to which adjacent orthogonals of waves refracted by a bottom whose contour lines are curved, are tangents. The occurrence of a caustic always marks a region of crossed orthogonals and high wave convergence.||Coastal Engineering|
|Cavitation||(Webster's Third New International Dictionary) The formation of partial vacuums in a liquid esp. as a result of the passage through it of a swiftly moving solid body.||Coastal Engineering|
|Cay||See key.||Coastal Engineering|
|Celerity of a gravity wave||This equation will find the average celerity of a gravity wave over a bed with a linear slope. This is useful in estimating the amount of phase lag needed to match a tide applied at a boundary to the tide at the gage being used to drive the boundary. Where - CAVG = the average celerityg = the acceleration due to gravity, h1 = the depth at the ocean boundary (the maximum depth), h2 = the depth at the inlet (the minimum depth)||Coastal Engineering|
|Celerity, wave||See wave celerity.||Coastal Engineering|
|Celerity||Wave speed.||Coastal Engineering|
|Cell Volume (biovolume)|
Cell volume (biovolume) determination is one of several common methods used to estimate biomass of algae in aquatic systems. Cell members of algae are used frequently in aquatic surveys as an indicator of algal production.
However, cell numbers alone cannot represent true biomass because of considerable cell-size variation among the algal species. Cell volume (µm3) is determined by obtaining critical cell measurements or cell dimensions (for example, length, width, height, or radius) for 20 to 50 cells of each important species to obtain an average biovolume per cell.
Cells are categorized according to the correspondence of their cellular shape to the nearest geometric solid or combinations of simple solids (for example, spheres, cones, or cylinders). Representative formulae used to compute biovolume are as follows:
sphere 4/3 pr3 cone 1/3 pr2h cylinder pr2h.
pi (p) is the ratio of the circumference to the diameter of a circle; pi = 3.14159….
From cell volume, total algal biomass expressed as biovolume (µm3/mL) is thus determined by multiplying the number of cells of a given species by its average cell volume and then summing these volumes for all species.
|Cells/ volume||Cells/volume refers to the number of cells of any organism that is counted by using a microscope and grid or counting cell. Many planktonic organisms are multicelled and are counted according to the number of contained cells per sample volume, and generally are reported as cells or units per milliliter (mL) or liter (L).||Coastal Engineering|
1. The principal point of a photograph.
2. The central point from which a map projection is geometrically based.
|Center-line hydrographic survey||(EM 1110-2-1003) A survey of the center line of a project alignment, or profile survey.||Coastal Engineering|
|Centibar||The unit of pressure equal to 1 ton per meter per second. (See also decibar.)||Coastal Engineering|
|Central pressure index (cpi)||The estimated minimum barometric pressure in the eye (approximate center) of a particular hurricane. The CPI is considered the most stable index to intensity of hurricane wind velocities in the periphery of the storm; the highest wind speeds are associated with storms having the lowest CPI.||Coastal Engineering|
|Cfs||See cubic feet per second (cfs).||Coastal Engineering|
|Cfs-day||Cfs-day (See “Cubic foot per second-day”)||Coastal Engineering|
|Chainage||Distance down a survey line from a given point.||Coastal Engineering|
|Change order||A written order, signed by the contracting officer, directing the contractor to make a change that the Changes clause authorizes the contracting officer to order without the contractor's consent.||Coastal Engineering|
|Change register||Record maintained to reflect all changes.||Coastal Engineering|
|Changed work||Work specifically changed by a change order.||Coastal Engineering|
|Channel bar||An elongate deposit of sand or gravel located in the course of a stream or tidal channel.||Coastal Engineering|
|Channel bars||Channel bars, as used in this report, are the lowest prominent geomorphic features higher than the channel bed.||Coastal Engineering|
|Channel capacity||The maximum flow which a channel is capable of transmitting without its banks being overtopped.||Coastal Engineering|
|Channel centerline||The line of the fastest current or the strongest flow of a channel; it generally coincides with (and is sometimes known as) the thalweg. See thalweg.||Coastal Engineering|
|Channel cross-section||The physical measurements (width and depth) across the channel and floodplain.||Coastal Engineering|
|Channel encroachment||The process by which an inlet channel migrates towards an otherwise relatively stable feature (e.g., inlet structure, embankment, spit).||Coastal Engineering|
|Channel erosion||Erosion in which material is removed by water flowing in well-defined courses; erosion caused by channel flow.||Coastal Engineering|
|Channel examination||See examination survey.||Coastal Engineering|
|Channel flow||Movement of surface runoff in a long narrow trough-like depression bounded by banks or valley walls that slope toward the channel.||Coastal Engineering|
|Channel meander||The process by which a portion of an inlet channel turns or winds along an indirect course.||Coastal Engineering|
|Channel migration||Lateral or longitudinal (down-valley) migration of the stream channel within the valley by the process of erosion and deposition.||Coastal Engineering|
|Channel pattern||The meander geometry of the channel within its active floodplain, readily visible from a top-down view of the channel.||Coastal Engineering|
|Channel prism||The channel design dimensions, including required side slopes, width, allowable overdepth, and advance maintenance.||Coastal Engineering|
|Channel profile||(or longitudinal profile) The plot of the stream bottom elevation (and often the water surface, bankfull and valley elevations) longitudinally along the stream. The change in bottom elevation over distance is called Channel Gradient.||Coastal Engineering|
|Channel scour||The erosive action of water and sediment that removes and carries away bed and bank material.||Coastal Engineering|
|Channel slope||(or Channel Gradient) - The inclination of the channel bottom, measured as the elevation drop per unit length of channel.||Coastal Engineering|
|Channel stabilization||A stable channel is neither progressively aggrading nor degrading, or changing its cross-sectional area through time. It could aggrade or degrade slightly, but over the period of a year, the channel would remain similar in shape and dimensions and position to previous times. Unstable channels are depositing or eroding in response to some exterior conditions. Stabilization techniques consist of bank protection and other measures that work to transform an unstable channel into a stable one.||Coastal Engineering|
|Channel storage||Simply water storage within the banks of the channel.||Coastal Engineering|
|Channel sweep hydrographic survey||(EM 1110-2-1003) A full-coverage survey/sweep of an excavated project using rigid bars or multiple-transducer echo sounding to determine the locations of obstructions or hard materials.||Coastal Engineering|
1. A natural or artificial waterway of perceptible extent which either periodically or continuously contains moving water, or which forms a connecting link between two bodies of water.
2. The part of a body of water deep enough to be used for navigation through an area otherwise too shallow for navigation.
3. A large strait, as the English Channel.
4. The deepest part of a stream, bay, or strait through which the main volume or current of water flows (see THALWEG).
|Channelization||The process of modifying - usually through straightening or deepening - the natural course of a waterway to accelerate conveyance or increase drainage of wet areas. Often referred to as hydromodification.||Coastal Engineering|
|Channel-mouth bar||A bar built where a stream enters a body of standing water, resulting from decreased flow velocity.||Coastal Engineering|
|Characteristic wave height||See SIGNIFICANT WAVE HEIGHT.||Coastal Engineering|
|Characteristic, in quality assurance||See quality characteristic.||Coastal Engineering|
|Characteristics method||Numerical method in which the governing partial differential equations of a mathematical model are transformed into characteristic (ordinary differential) equations.||Coastal Engineering|
|Chart datum||The plane or level to which soundings (or elevations) or tide heights are referenced (usually LOW WATER DATUM). The surface is called a tidal datum when referred to a certain phase of tide. To provide a safety factor for navigation, some level lower than MEAN SEA LEVEL is generally selected for hydrographic charts, such as MEAN LOW WATER or MEAN LOWER LOW WATER. See DATUM PLANE.||Coastal Engineering|
|Chart evaluation survey||A hydrographic survey of less than "basic" classification serving to provide a rapid means of determining the adequacy and accuracy of charted data.||Coastal Engineering|
|Chart, as in nautical||A special purpose map specifically designed to meet the requirements of, and promote safe marine navigation. Included on most nautical charts are - depths of water, characteristics of the bottom, elevations of selected topographic features, general configuration of the coast or shoreline, dangers, obstructions and aids to navigation, limited tidal data, and information about magnetic variation in the charted area.||Coastal Engineering|
|Chart||A special-purpose map, esp. one designed for navigation such as a bathymetric chart.||Coastal Engineering|
|Charts||Compact Hydrographic Airborne Rapid Total Survey||Coastal Engineering|
|Check dam||A low dam constructed of logs, loose rock, or other material, to control water flow and check erosion.||Coastal Engineering|
|CHEMetrics Water Quality Test Kits|
CHEMetrics, Inc. (website: http://www.chemetrics.com/) is one of a number of companies that market a variety of test kits and field and lab instruments for water quality testing. Additional companies commonly cited are Hach and LaMotte, and there are probably numerous others accessible to the reader through various educational resources or scientific lab products catalogues. Water on the Web does not endorse any particular company’s products. Some test kits have been "approved" by state or federal agencies for certain types of tests in specific types of water or wastewater.
.A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction.
.The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as dipole-dipole interactions, the London dispersion force and hydrogen bonding.
Concentrations of reactants and products at which a reaction is in balance; there is no net exchange because the rate of the forward reaction is taking place at the same rate of the reverse reaction.
|Chemical oxygen demand||(EM 1110-2-5026) The amount of oxygen required to oxidize organic chemical compounds and oxidizable inorganic compounds in a body of water. These chemicals rapidly oxidize, requiring great quantities of oxygen.||Coastal Engineering|
|Chemical weathering||Disintegration of rocks and sediments by chemical alteration of the constituent minerals or of the cementing matrix. It is caused by exposure, oxidation, temperature changes, and biological processes.||Coastal Engineering|
|Chemocline||Sharp gradient in chemical concentration; the boundary in a meromictic lake separating an upper layer of less-saline water that can mix completely at least once a year (mixolimnion) from a deeper, more saline (dense) layer (monimolimnion) that never is mixed into the overlying layer.||Coastal Engineering|
A strand plain, occupied by cheniers and intervening mud flats with marsh and swamp vegetation. Chenier plains develop when (1) substantial quantities of river-supplied mud become available for nearshore marine transport and coastal mudflat deposition;
(2) a balance exists between longshore sand transport, deposition, and erosional sand-winnowing
(3) these two conditions alternate.
|Chenier||A long, narrow wooded beach ridge or sandy hummock forming roughly parallel to a prograding shore, usually seaward of marsh and mud-flat deposits (as along the south coast of Louisiana)||Coastal Engineering|
|Chimney||An angular, columnar mass of rock, smaller than a stack, isolated on a wave-cut platform by differential wave erosion of a sea cliff.||Coastal Engineering|
|Chip||The transition time for individual bits in the pseudo-random sequence. Also, an integrated circuit.||Coastal Engineering|
|Chlorinated hydrocarbons||(EM 1110-2-5026) Polychlorinated biphenyls (PCBs) and similar compounds which can be harmful to living organisms, and which can sometimes be found in certain dredged material substrates, especially in urban areas and especially in fine-grained material.||Coastal Engineering|
|Chlorinity (cl)||The number giving the chlorinity in grams per kilogram of a seawater sample is identical with the number giving the mass in grams of atomic weight silver just necessary to precipitate the halogens in 0.3285233 kilogram of the seawater sample. S(0/00) = 1.80655 x Cl(0/00) where S(0/00 is the salinity in parts per thousand. (See also salinity.)||Coastal Engineering|
Green pigment in plants that transforms light energy into chemical energy in photosynthesis.
|Chock||A wedge or block of wood, metal, or the like for filling in a space, holding an object steady, preventing motion, 2) A shaped support or cradle for a ship's boat, barrel, etc.||Coastal Engineering|
|Chop||The short-crested waves that may spring up quickly in a moderate breeze, and which break easily at the crest. Also WIND CHOP.||Coastal Engineering|
|Choppy sea||Short, rough waves tumbling with a short and quick motion. Short-crested waves that may spring up quickly in a moderate breeze, and break easily at the crest.||Coastal Engineering|
|Christmas tree arrangement||A system of three swing wires located at the stern of the pipeline dredge used in place of a spud for advancement of the dredge.||Coastal Engineering|
|Circadian||Said of a time period approximately 24 hours in length, or of an event occurring at roughly 24-hour or daily intervals.||Coastal Engineering|
|Civil day||A mean solar day commencing at midnight.||Coastal Engineering|
|Civil engineering||A branch of engineering concerned primarily with the investigation, design, construction, operation, and maintenance of civil-works projects (public and private) such as highways, bridges, tunnels, waterways, harbors, dams, water supply, irrigation, railways, airports, buildings, sewage disposal, and drainage.||Coastal Engineering|
|Civil time||Time in which the day begins at midnight as distinguished from the former astronomical time in which the day began at noon.||Coastal Engineering|
|Claim||(FAR 33.001) A written demand or written assertion by one of the contracting parties seeking, as a matter of right, the payment of money in a certain sum, the adjustment or interpretation of contract terms, or other relief arising under or relating to the contract.||Coastal Engineering|
|Clam flat||(EM 1110-2-5026) Any aquatic habitat, both natural and man-made, occupied by colonies of clams, including those occurring in shellfish farming operations. (See also beneficial uses.)||Coastal Engineering|
|Clamshell dredge||See dredge, mechanical, cable excavator, clamshell.||Coastal Engineering|
The French equivalent for a type of STANDING WAVE. In American usage it is usually associated with the standing wave phenomenon caused by the reflection of a nonbreaking wave train from a structure with a face that is vertical or nearly vertical. Full clapotis is one with 100 percent reflection of the incident wave; partial clapotis is one with less than 100 percent reflection.
|Clarity||The observed clearness of the water.||Coastal Engineering|
|Clarke Ellipsoid of 1866||The ellipsoid of reference for geodetic surveys in North and Central America, the Hawaiian Islands, and the Philippines. It was the basis of the North American datum of 1927.||Coastal Engineering|
|Classification, as in tide||See type of tide.||Coastal Engineering|
|Clastic rocks||Rocks built up of fragments which have been produced by weathering and erosion of pre-existing rocks and minerals and, typically, transported mechanically to their point of deposition.||Coastal Engineering|
|Clastic sediment||A sediment formed by the accumulation of fragments derived from preexisting rocks or minerals and transported as separate particles to their places of deposition by purely mechanical agents (such as water, wind, ice, and gravity); gravel, sand, mud, clay.||Coastal Engineering|
|Clay balling||The facility of a clay soil to form balls during pipeline transport.||Coastal Engineering|
|Clay size||(ASTM D 653) That portion of the soil finer than 0.002 mm (0.005 mm in some cases. (See also clay.)||Coastal Engineering|
|Clay soil||See clay; clay size.||Coastal Engineering|
A fine grained, plastic, sediment with a typical grain size less than 0.004 mm. Possesses electromagnetic properties which bind the grains together to give a bulk strength or cohesion. See SOIL CLASSIFICATION.
|Clean out||(Huston. Hydraulic Dredging Principles...) Fitting near the suction mouth of a pump to allow entry into the pump to clean out obstacles caught in the runner.||Coastal Engineering|
|Clean up||Process of redredging an area to pick up loose material previously cut but left behind.||Coastal Engineering|
|Clean water act||(P. L. 92-500, as amended (40 CFR 230)), Governs discharge of dredged or fill material in waters of the US inside the baseline. (See also Legislative Appendix.)||Coastal Engineering|
|Cliff||A high, steep face of rock; a precipice. See also SEA CLIFF.||Coastal Engineering|
|Climate||The characteristic weather of a region, particularly regarding temperature and precipitation, averaged over some significant internal of time (years).||Coastal Engineering|
|Climax community||A mature, relatively stable biotic community representing the culmination of ecological succession.||Coastal Engineering|
|Clock bias||The difference between the clock's indicated time and true universal time.||Coastal Engineering|
|Clogging of the riverbed|
Refers generally to changes in the exchange processes between the river and groundwater. These processes are usually described as infiltration and filtering, and they are accompanied by change in; flow throughout the riverbed, mechanical filtering or sieving, sorption, chemical oxidation and reduction and ion exchange.
Progressive choking or settling of solids in a pipeline to the extent that the flow of the fluid is impeded with eventual complete blockage if sufficient water is not allowed to enter the suction.
|Closed bucket dredge||See dredge, mechanical, cable excavator, clamshell, closed bucket.||Coastal Engineering|
|Closed-nose cutter||See cutterhead.||Coastal Engineering|
|Closing line||The line dividing inland waters and the territorial sea at the mouth of a river, bay, or harbor.||Coastal Engineering|
The water depth beyond which repetitive profile or topographic surveys (collected over several years) do not detect vertical sea bed changes, generally considered the seaward limit of littoral transport. The depth can be determined from repeated cross-shore profile surveys or estimated using formulas based on wave statistics. Note that this does not imply the lack of sediment motion beyond this depth.
|Cnoidal wave||A type of wave in shallow water (i.e., where the depth of water is less than 1/8 to 1/10 the wavelength). The surface profile is expressed in terms of the Jacobian elliptic function cn u; hence the term cnoidal.||Coastal Engineering|
|Coagulation||The agglomeration of colloidal or finely divided suspended matter, generally caused by the addition of a chemical coagulant.||Coastal Engineering|
|Coarse clay||A geologic term for a clay particle having a diameter in the range of 1/512 to 1/256 mm (2-4 microns, or 9 to 8 phi units). Also, a loose aggregate of clay consisting of coarse clay particles.||Coastal Engineering|
1. A geologic term for a sand particle having a diameter in the range of 0.5-1 mm (500-1000 microns, or 1 to zero phi units). Also, a loose aggregate of sand consisting of coarse sand particles.
2. An engineering term for a sand particle having a diameter in the range of 2 mm (retained on U.S. standard sieve no.10) to 4.76 mm (passing U.S. standard sieve no. 4).
3. A soil term used in the U.S. for a sand particle having a diameter in the range of 0.5-1 mm.
|Coarse silt||A geologic term for a silt particle having a diameter in the range of 1/32 to 1/16 mm (31-62 microns, or 5 to 4 phi units). Also, a loose aggregate of silt consisting of coarse silt particles.||Coastal Engineering|
|Coast and geodetic survey|
A former name of the National Ocean Service. The organization was known as - The Survey of the Coast from its founding in 1807 to 1836, Coast Survey from 1836 to 1878, Coast and Geodetic Survey from 1878 to 1970, and National Ocean Survey from 1970 to 1982. In 1982 it was named National Ocean Service. From 1965 to 1970, the Coast and Geodetic Survey was a component of the Environmental Science Services Administration (ESSA). The National Ocean Survey was a component of the National Oceanic and Atmospheric Administration (NOAA).
NOAA became the successor to ESSA in 1970. The National Ocean Service is a component of NOAA, U.S. Department of Commerce.
The low water datum line for purposes of the Submerged Lands Act (P.L. 31). (See also shoreline.)
The term used in the Submerged Lands Act to describe the low-water line and closing lines across the mouths of inland water bodies.
|Coast||1. A strip of land of indefinite width (may be several kilometers) that extends from the SHORELINE inland to the first major change in terrain features.|
2. The part of a country regarded as near the coast.
|Coastal area||The land and sea area bordering the shoreline.||Coastal Engineering|
The mean high water line (MHWL) or mean higher high water line (MHHWL) when tidal lines are used as the coastal boundary. Also, lines used as boundaries inland of and measured from (or points thereon) the MHWL or MHHWL.
1. Those currents which flow roughly parallel to the shore and constitute a relatively uniform drift in the deeper water adjacent to the surf zone. These currents may be tidal currents, transient, wind-driven currents, or currents associated with the distribution of mass in local waters.
2. For navigational purposes, the term is used to designate a current in coastwise shipping lanes where the tidal current is frequently rotary.
|coastal defense||General term used to encompass both coast protection against erosion and sea defense against flooding.||Coastal Engineering|
1. The formation of a bay, as by the sea overflowing a depression of the land near the mouth of a river.
2. A bay, either the deep indentation or recess of a shoreline, or the large body of water thus formed.
The total energy, including that of wind, waves, tides, and currents, available for work along the coast. Most well-known coasts are characterized as dominated by wave energy.
|Coastal engineering||A branch of civil engineering that applies engineering principles specifically to projects within the coastal zone (nearshore, estuary, marine, and shoreline).||Coastal Engineering|
|Coastal forcing||The natural processes which drive coastal hydro- and morphodynamics (e.g.winds, waves, tides, etc).||Coastal Engineering|
|Coastal model||Model of a coastal area. Often a movable bed model used to reproduce coastal sediment transport.||Coastal Engineering|
|Coastal plain||The plain composed of horizontal or gently sloping strata of clastic materials, generally representing a strip of sea bottom that has emerged from the sea in recent geologic time. May extend inland many km.||Coastal Engineering|
|Coastal processes||Collective term covering the action of natural forces on the SHORELINE, and near shore seabed.||Coastal Engineering|
A zone directly adjacent to the waterline, where only coast related activities take place. Usually this is a strip of some 100 m wide. In this strip the coastal defense activities take place. In this strip often there are restrictions to land use.
|Coastal zone (legal definition for coastal zone management)|
The term coastal zone means the coastal waters (including the lands therein and thereunder) and the adjacent shorelands (including the waters therein and thereunder), strongly influenced by each and in proximity to the shorelines of the several coastal states, and includes islands, transitional and intertidal ares, salt marshes, wetlands, and beaches. The zone extends, in Great Lakes waters, to the international boundary between the United States and Canada and in other areas seaward to the outer limit of the United States territorial sea.
The zone extends inland from the shorelines only to the extent necessary to control shorelands, the uses of which have a direct and significant impact on the coastal waters. Excluded from the coastal zone are lands the use of which is by law subject solely to the discretion of or which is held in trust by the Federal Government, its officers, or agents.
|Coastal zone management|
The integrated and general development of the coastal zone. Coastal Zone Management is not restricted to coastal defense works, but includes also a development in economical, ecological and social terms. Coastline Management is a part of Coastal Zone Management.
The transition zone where the land meets water, the region that is directly influenced by marine and lacustrine hydrodynamic processes. Extends offshore to the continental shelf break and onshore to the first major change in topography above the reach of major storm waves. On barrier coasts, includes the bays and LAGOONS between the BARRIER and the mainland.
1. Technically, the line that forms the boundary between the coast and the shore.
2. Commonly, the line that forms the boundary between the land and the water, esp. the water of a sea or ocean. The SHORELINE. A more general term than COAST LINE.
|Cobble (cobblestone)||A rock fragment between 64 and 256 mm in diameter, usually rounded. See SOIL CLASSIFICATION.||Coastal Engineering|
|Cobble||Gravel and stones that have been rounded by abrasive action of flowing water or waves.||Coastal Engineering|
|Cobblestone||Rock particle having a diameter between 75 and 305 millimetres.||Coastal Engineering|
|Cocurrent line||A line on a map or chart passing through places having the same current hour.||Coastal Engineering|
|Coefficient of friction||See coefficient of internal friction.||Coastal Engineering|
|Coefficient of Heat Transfer|
The ratio of the temperature of an object to the temperature of its surroundings. The change in temperature of an object is directly proportional to the difference between its temperature and the temperature of its surroundings.
|Coefficient of internal friction||(ASTM D 653) The tangent of the angle of internal friction (angle of shear resistance).||Coastal Engineering|
|Coefficient of permeability (permeability)||(ASTM D 653) The rate of discharge of water under laminar flow conditions through a unit cross-sectional area of a porous medium under a unit hydraulic gradient and standard temperature conditions (usually 20?C).|
|Coefficient of thermal expansion||The change in linear dimension per unit length divided by the temperature change.||Coastal Engineering|
|Coefficient of uniformity||(Mod from ASTM D 653) The ratio D60/D10, where D60 and D10 are the particle diameters corresponding, respectively, to 60% finer and 10% finer on the cumulative particle-size distribution curve.||Coastal Engineering|
|Coefficient of viscosity||The rate of increase of shearing resistance of a fluid mixture of soil and water corresponding to an increase in the shearing rate. (See also viscosity.)||Coastal Engineering|
|Cofferdam||A temporary watertight structure enclosing all or part of the construction area so that construction can proceed in the dry.||Coastal Engineering|
|Cohesion||(ASTM D 653) The portion of the shear strength of a soil indicated by the term c, in Coulomb's equation, s = c + p tan f.||Coastal Engineering|
|Cohesionless soil||A soil having little or no cohesive binder whose shear strength is derived entirely by grain-to-grain contact and that can be densified, or compacted, by vibration.||Coastal Engineering|
|Cohesive Forces||All the forces of attraction among particles of a liquid.||Coastal Engineering|
|Cohesive materials||See cohesive soil.||Coastal Engineering|
|Cohesive sediment||Sediment containing significant proportion of clays, the electromagnetic properties of which cause the sediment to bind together.||Coastal Engineering|
|Cohesive soil||A soil containing sufficient plastic clay to inhibit grain-to-grain contact during shear and that can not be significantly densified by vibration.||Coastal Engineering|
|Coldwater stream||A stream with water temperatures low enough to support salmonid fishes.||Coastal Engineering|
|Collapsing breaker||A type of wave where breaking occurs over the lower half of wave, with minimal air pocket and usually no splash-up. Bubbles and foam present.||Coastal Engineering|
|Collection pond||Pond located on the landside of a levee where interior floodwaters collect.||Coastal Engineering|
|Colliforms (total and faecal)||Bacteria associated with faeces.||Coastal Engineering|
|Collocated||Two or more objects placed together at the same location.||Coastal Engineering|
1. As a size term, refers to particles smaller than 0.00024 mm, smaller than clay size.
2. Finely divided solids which do not settle in a liquid but which may be coagulated chemically or biochemically.
|Colluvial features||Landforms that are not well developed by the river. Sediments are typically angular and jagged.||Coastal Engineering|
(EM 1110-2-5026) A term used to describe the habit of numerous bird species, especially waterbirds, of nesting in large groups, often with nests only one to two feet apart. (See also beneficial uses.)
|Comber||1. A DEEPWATER wave whose crest is pushed forward by a strong wind; much larger than a whitecap.|
2. A long-period breaker.
|Combined sewer overflow||An outlet for storm water and untreated sewage during large rainfall or runoff events.||Coastal Engineering|
|Comminuted material||Rock material which has been broken up into smaller pieces either by blasting or mechanical excavation.||Coastal Engineering|
|Community||All of the populations of plants or animals in an area or volume; a complex association usually containing both animals and plants.||Coastal Engineering|
|Compactability||The relative ease with which a soil can be compacted.||Coastal Engineering|
|Compaction||(ASTM D 653) The densification of a soil by means of mechanical manipulation.||Coastal Engineering|
Relative density; the degree of packing, or densification, of a cohesionless soil. (See also relative density.) very loose--relative density = 0 - 15 percent loose--relative density = 15 - 35 percent medium (firm)--relative density = 35 - 65 percent dense--relative density = 65 - 85 percent very dense--relative density = 85 - 100 percent.
|Comparison of simultaneous observations|
A reduction process in which a short series of tide or tidal current observations at any place is compared with simultaneous observations at a control station where tidal or tidal current constants have previously been determined from a long series of observations. For tides, it is usually used to adjust constants from a subordinate station to the equivalent of that which would be obtained from a 19-year series.
Direction as indicated by compass without any allowances for compass error. The direction indicated by a compass may differ by a considerable amount from true or magnetic direction.
|Compass error||The angular difference between a compass direction and the corresponding true direction. The compass error combines the effects of deviation and variation.|
|Compensated cutterhead dredge||See dredge, hydraulic, pipeline, cutterhead, compensated.||Coastal Engineering|
|Competence||The ability of a wind or water current to transport detritus, in terms of particle size rather than amount, measured as the diameter of the largest particles.||Coastal Engineering|
|Competition in contracting act of 1984, cica|
The Competition in Contracting Act of 1984 substantially changes the basic statutes underlying the federal procurement system and is effective 1 April 1985. Under the new coverage, agencies will be required to provide for full and open competition by soliciting sealed bids or requesting competitive proposals, or use other competitive procedures, unless a statutory exception permits other than full and open competition. There are new justification, approval, and notice requirements for contracts employing other than full and open competition.
The coverage also requires appointment of competition advocates and enumerates their responsibilities. It also establishes new provisions relating to bid protests filed on or after January 15, 1985.
An environment of varying dimensions relating to buy-sell relationships in which the buyer induces, stimulates, or relies on marketplace conditions in causing independent sellers to contend confidently for the award of a contract.
The Federal Government sets forth in the Federal Acquisition Regulation the major competitive environments wherein its needs and requirements are to be procured and satisfied. The first, full and open competition among all responsible sources (FAR 6.1); the second, full and open competition after the exclusion of sources (FAR 6.2); and the third, other than full and open competition under seven permissive circumstances (FAR 6.3).
A negotiated procurement that -
1)Is initiated by a request for proposals, which sets forth the government's requirements and the criteria for the evaluation of offers.
2)Contemplates the submission of timely proposals by the maximum number of possible offerors.
3)May provide for discussion with those offerors found to be within a competitive range.
4)Concludes with the award of a contract to the offeror whose offer, considering only price and the other factors included in the solicitation, is most advantageous to the government.
|Complex spit||A large RECURVED SPIT with secondary spits developed at its end. Example : Sandy Hook, New Jersey.||Coastal Engineering|
|Component||1. Same as constituent.|
2. That part of a tidal current velocity which, by resolution into orthogonal vectors, is found to act in a specified direction.
|Composite sample||A sample formed by combining two or more individual samples, or representative portions thereof.||Coastal Engineering|
|Compound tide||A harmonic tidal (or tidal current) constituent with a speed equal to the sum or difference of the speeds of two or more elementary constituents. The presence of compound tides is usually attributed to shallow water conditions.||Coastal Engineering|
The maximum resistance of a concrete or mortar specimen to axial loading, expressed as force per unit cross-sectional area, or the specified resistance used in design calculations, in the US customary units of measure expressed in pounds per square inch and designated 1~ (ACI 116R-85).
|Concentration of dredged mixture||See density.||Coastal Engineering|
|Concentration of sediment||The dry weight of sediment per unit volume of waters ediment mixture, i.e. mg/l or ppm.||Coastal Engineering|
A simplified representation of the physical hydrogeologic setting. This includes the identification and description of the geologic and hydrologic framework, media type, hydraulic properties, and sources and sinks of flow.
|Concrete||A composite material that consists essentially of a binding medium which is embedded particles or fragments of aggregate; in portland cement concrete, the binder is a mixture of portland cement and water (ACI 116R-85).||Coastal Engineering|
|Condition survey||Controlled survey of lesser accuracy. (See also reconnaissance survey.)||Coastal Engineering|
|Conduction||Thermal conduction is the transfer of heat between two solid materials that are physically touching each other.||Coastal Engineering|
|Conductivity (electrical conductivity and specific conductance)|
Measures water's ability to conduct an electric current and is directly related to the total dissolved salts (ions) in the water. Called EC for electrical conductivity and is reported in micromhos per centimeter (umhos/cm) which has been recently renamed as uS/cm (microSiemans per centimeter). EC is temperature sensitive and increases with increasing temperature. Most modern probes automatically correct for temperature and standardize all readings to 25°C and then refer to the data as specific EC.
|Conductivity||A measure of the amount of salts dissolved in water.||Coastal Engineering|
|Cone angle||The angle viewed from perpendicular to a transducer face at which a sound pulse spreads.||Coastal Engineering|
|Cone penetrometer||See static cone penetration test.||Coastal Engineering|
|Confidence interval||In quality assurance, the range of values that has a designated degree of assurance of including the true value, or accepted reference value, upon repeated sampling.||Coastal Engineering|
|Confidence level||In quality assurance, the probability that a confidence interval includes the true value or accepted reference value.||Coastal Engineering|
|Confidence limits||In quality assurance, the maximum and minimum values which define the confidence interval.||Coastal Engineering|
|Confined disposal area||See confined disposal facility.||Coastal Engineering|
|Confined disposal facility, cdf|
Diked area constructed to contain dredged material. Sediment is retained in the CDF while effluent is discharged by a control structure such as a weir. The objective of the design and operation of a CDF is to meet applicable effluent standards pertaining to suspended solids and to provide required storage capacity. The terms confined disposal facility (CDF), dredged material containment area, dike disposal facility, and confined disposal area are used interchangeably in the literature. (See also dike; effluent;weir.)
|Confined dredged material placement||Dredged material placed in a confined disposal facility (CDF). (See also confined disposal facility.)||Coastal Engineering|
|Confining layer||A body of relatively impermeable material that is statigraphically adjacent to one or more aquifers. It may lie above or below the aquifer.||Coastal Engineering|
|Confirmation||Process in which a model of a specific study area is built and tested to prove that the model design and implementation is adequate and no major phenomenon has been overlooked.||Coastal Engineering|
|Conflict in plans and specifications||Statements or meanings in the contract specifications and drawings which cannot be reconciled by reasonable interpretation.|
|Confluence||The junction of two or more river reaches or channels (the opposite of a bifurcation).||Coastal Engineering|
|Consent of surety||An acknowledgement by a surety that its bond given in connection with a contract continues to apply to the contract as modified.||Coastal Engineering|
|Consequential cost||That part of construction costs which are speculative and so remote they cannot be related to the work.||Coastal Engineering|
|Consistency limits||See Atterberg limits.||Coastal Engineering|
The relative ease with which a cohesive soil can be deformed; based on the unconfined compressive strength. fluid-compressive strength is less than zero. very soft-compressive strength = 0 - 0.25 TSF (0 - 25 kPa) soft-compressive strength = 0.25 - 0.50 TSF (25 - 50 kPa) medium (firm)-compressive strength = 0.50 - 1.00 TSF (50 - 100 kPa) stiff-compressive strength = 1.00 - 2.00 TSF (100 - 200 kPa) very stiff-compressive strength = 2.00 - 4.00 TSF (200 - 400 kPa)
hard-compressive strength = over 4.00 TSF (over 400 kPa)
|Consolidation||The gradual, slow compression of a cohesive soil due to weight acting on it, which occurs as water is driven out of the voids in the soil. Consolidation only occurs in clays or other soils of low permeability.||Coastal Engineering|
|Constants, current||See current constants.||Coastal Engineering|
|Constants, harmonic||See harmonic constants.||Coastal Engineering|
|Constants, tidal||See tidal constants.||Coastal Engineering|
The time of the rotation of the Earth with respect to a fictitious celestial body representing one of the periodic elements in the tidal forces. It approximates in length the lunar or solar day and corresponds to the period of a diurnal constituent or twice the period of a semidiurnal constituent. The term is not applicable to the long-period constituents.
|Constituent hour||One twenty-fourth part of a constituent day.||Coastal Engineering|
|Constituent transport model||A model that would track the movement of a water quality constituent (salinity for example) throughout the water body.||Coastal Engineering|
One of the harmonic elements in a mathematical expression for the tide-producing force and in corresponding formulas for the tide or tidal current. Each constituent represents a periodic change or variation in the relative positions of the Earth, Moon.
|Constructed dimensions||(ER 1130-2-307) Channel dimensions which have been provided by initial or new work dredging. These dimensions are equal to or less than the authorized dimensions. Also referred to as as built.||Coastal Engineering|
|Construction block||In quality assurance, a measured amount of construction assumed to be produced by the same process.||Coastal Engineering|
|Construction dredging||The one-time removal of sediments to create navigable waterways. (See also new work dredging.)||Coastal Engineering|
|Construction joint||The surface between two consecutive placements of concrete that develops bond strength.||Coastal Engineering|
|Construction||In quality assurance, the result of processing and/or placing materials or products in accordance with explicitly stated conditions.||Coastal Engineering|
|Consumer's risk||In quality assurance, the risk of accepting a block of construction that does not comply with the specifications.||Coastal Engineering|
|Consumers||Organisms that must eat other organisms for their energy metabolism; organisms that cannot produce new organic matter by photosynthesis or chemosynthesis (producers).||Coastal Engineering|
|Containment area||See confined disposal facility.||Coastal Engineering|
|Contaminant||A chemical or biological substance in a form that can be incorporated into, onto, or be ingested by and that harms aquatic organisms, consumers of aquatic organisms, or users of the aquatic environment.||Coastal Engineering|
|Contaminated sediment or contaminated dredged material||Sediments or materials that have been demonstrated to cause an unacceptable adverse effect on human health or the environment.||Coastal Engineering|
1. That part of the continental margin that is between the shoreline and the continental slope (or, when there is no noticeable continental slope, a depth of 200 m). It is characterized by its very gentle slope of 0.10.
2. The area under active littoral processes during the Holocene period.
3. The zone bordering a continent extending from the line of permanent immersion to the depth, usually about 100 m to 200 m, where there is a marked or rather steep descent toward the great depths of the ocean.
4. The area under active littoral processes during the HOLOCENE period.
5. The region of the oceanic bottom that extends outward from the shoreline with an average slope of less than 1:100, to a line where the gradient begins to exceed 1:40 (the CONTINENTAL SLOPE).
1.That part of the continental margin that is between the continental shelf and the continental rise (or oceanic trench). It is characterized by its relatively steep slope of 3-6 degrees.
2.The declivity from the offshore border of the CONTINENTAL SHELF to oceanic depths. It is characterized by a marked increase in slope.
The term continuity used herein is a check of the water mass flux at locations for use in a test of the satisfaction of the continuity equation. The continuity check lines are typically used to estimate the flow rates and serve as an error indicator.
|Contour interval||The difference in value between two adjacent contours; specifically, the vertical distance between the elevations represented by two successive contour lines on a topographic map. It is generally a regular unit chosen according to the amount of vertical distance involved and the scale of the map, but it need not be constant over the entire map (a variable contour interval may be used for optimum portrayal of relief features).||Coastal Engineering|
1. A line drawn on a map or chart representing a contour. Present usage makes contour and contour line synonymous: a line connecting points of equal value (generally elevation) above or below some reference value such as a datum plane.
2. A term used loosely in the general sense of an isopleth; for example, a line (on a map) connecting points of equal magnitude of a mass property of a sediment (as of porosity, permeability, color, or thickness, or of size, shape, or roundness of sedimentary particles).
|Contour||A line on a map or chart representing points of equal elevation with relation to a DATUM. It is called an ISOBATH when connecting points of equal depth below a datum. Also called DEPTH CONTOUR.|
|Contract acceptance survey||(EM 1110-2-1003) A final survey performed over a construction area or dredging acceptance section to determine quality and/or quantity of construction.||Coastal Engineering|
|Contract clause||Any general (boiler plate), special, or technical provision, or part thereof, of a contract.||Coastal Engineering|
|Contract completion date||Date established by the contract for the completion of all or specified portions of work.||Coastal Engineering|
|Contract depth||Dredging depth required by plans or specifications, not including allowable overdepth.||Coastal Engineering|
|Contract payment survey||(EM 1110-2-1003) Any survey intended to measure the amount of contract payment or performance. (See also contract survey.)||Coastal Engineering|
|Contract survey||(EM 1110-2-1003) 1) Any hydrographic survey associated with contracted construction activities including payments. 2) any hydrographic survey completed by a contractor.||Coastal Engineering|
|Contract||All types of agreements and orders for the procurement of supplies or services. It includes awards and notices of award, fixed-price, cost, cost-plus-fixed-fee, or incentive contracts, letter contracts, and purchase orders.||Coastal Engineering|
|Contracting modification||Any written change in the terms of the contract.||Coastal Engineering|
|Contracting officer, co||See EFARS Subchapter A; 1.602-1 or, Authorities.||Coastal Engineering|
|Contracting officer's representative, cor||See EFARS 1.603-3/90.||Coastal Engineering|
|Injection of grout into contraction joints.||Coastal Engineering|
|Contraction joint||A formed surface, usually vertical, in a dam to create a plane for the regulation of volumetric changes.||Coastal Engineering|
|Contractor caused delay||A significant slowing down or stopping of a contractor's scheduled progress in completing work required under a contract which is the result of acts of the contractor. These are usually inexcusable delays when considering justification for time extensions for the contract.||Coastal Engineering|
|Control chart||In quality assurance, a graphic method used in quality control for displaying data for the purpose of detecting assignable causes of variations in a repetitive process.||Coastal Engineering|
|Control current table||A current station at which continuous velocity observations have been made over a minimum period of 29 days. Its purpose is to provide data for computing accepted values of the harmonic and nonharmonic constants essential to tidal current predictions and circulatory studies. The data series from this station serves as the control for the reduction of relatively short series from subordinate current stations through the method of comparison of simultaneous observations. (See also current station; subordinate current station.)||Coastal Engineering|
|Control of quality, in quality assurance||See quality control.||Coastal Engineering|
|Control point||An accurately located point, mark, or object on the ground, whose horizontal and/or vertical position is used as a base for a dependent survey; any surveyed point used for horizontal and/or vertical control.||Coastal Engineering|
|Control sediment||(Dredged Material Testing Manual) A natural sediment essentially free of contaminants and compatible with the biological needs of the test organisms such that it has no discernable influence on the response being measured in the test. Test procedures are conducted with the control sediment in the same way as the reference sediment and dredged material. The purpose of the control sediment is to confirm the biological acceptability of the test conditions and to help verify the health of the organisms during the test.|
Excessive mortality in the control sediment indicates a problem with the test conditions or organisms, and can invalidate the results of the corresponding dredged material test.
|Control station||See primary control tide station; secondary control tide station; control current station.||Coastal Engineering|
|Control survey||A survey that provides horizontal- and/or vertical-position data for the support or control of subordinate surveys or for mapping (e.g., a survey that provides the geographic positions and/or plane coordinates of triangulation and traverse stations and the elevations of bench marks). Control surveys are classified according to their precision and accuracy.||Coastal Engineering|
|Control||A downstream channel feature--a channel constriction, a bedrock outcrop, a gravel bar, woody debris, an artificial structure--in the channel that physically influences the upstream water-surface elevation.||Coastal Engineering|
|Controllable-pitch propeller||A propeller, usually of the built-up type, whose blades can be rotated upon their own axis.||Coastal Engineering|
|Controlled hydrographic survey||Any hydrographic survey performed with horizontal control.||Coastal Engineering|
|Controlling depth||The least depth in the navigable parts of a waterway, governing the maximum draft of vessels that can enter.||Coastal Engineering|
|Convection Currents||Air or water movement caused by changes in density or thermal (temperature) gradients.||Coastal Engineering|
|Convergence||1. In refraction phenomena, the decreasing of the distance between orthogonals in the direction of wave travel. Denotes an area of increasing wave height and energy concentration.|
2. In wind-setup phenomena, the increase in setup observed over that which would occur in an equivalent rectangular basin of uniform depth, caused by changes in planform or depth; also the decrease in basin width or depth causing such increase in setup.
|Conveyance||A measure of the flow carrying capacity of a channel section. Flow is directly proportional to conveyance for steady flow. From Manning’s equation, the proportionality factor is the square root of the energy slope.||Coastal Engineering|
|Coordinated universal |
|A "time" referencing term which supersedes, but is generally equivalent to "Greenwich Mean Time" (GMT). The new TMC time scale is almost perfectly constant, since it is based upon ultra-stable atomic clocks. GMT was based upon a form of solar time keeping and was roughly the same as UTC.||Coastal Engineering|
|Coral draghead||See drag head.||Coastal Engineering|
|Coral reef||A coral-algal mound or ridge of in-place coral colonies and skeletal fragments, carbonate sand, and organically-secreted calcium carbonate. A coral reef is built up around a wave-resistant framework, usually of older coral colonies.||Coastal Engineering|
|Coral||1. (Biology) Marine coelenterates (Madreporaria), solitary or colonial, which form a hard external covering of calcium compounds or other materials. The corals which form large REEFS are limited to warm, shallow waters, while those forming solitary, minute growths may be found in colder waters to great depths.|
2. (Geology) The concretion of coral polyps, composed almost wholly of calcium carbonate, forming reefs and tree-like and globular masses. May also include calcareous algae and other organisms producing calcareous secretions, such as bryozoans and hydrozoans.
|Corange line||A line passing through places of equal tidal range.||Coastal Engineering|
|Core drilling; diamond drilling||(ASTM D 653) A rotary drilling technique, using diamonds in the cutting bit, that cuts out cylindrical rock samples.||Coastal Engineering|
|Core||1. A cylindrical sample extracted from a beach or seabed to investigate the types and depths of sediment layers.|
2. An inner, often much less permeable portion of a BREAKWATER or BARRIER BEACH.
|Coriolis effect||Force due to the Earth's rotation, capable of generating currents. It causes moving bodies to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The "force" is proportional to the speed and latitude of the moving object. It is zero at the equator and maximum at the poles.||Coastal Engineering|
|Coriolis force||A term in the relative hydrodynamic equations of motion that takes into account the effect of the Earth's rotation on moving objects (including air and water) when viewed with reference to a coordinate system attached to the rotating Earth. The horizontal component is directed 90? to the right (when looking in the direction of the motion) in the Northern Hemisphere and 90? to the left in the Southern. The horizontal component is zero along the Equator; also, when the object is at rest relative to the Earth.|
The Coriolis acceleration = 2vO sin f where v is the speed of the object, O is the angular velocity of the Earth, and f is the latitude. Named for Gaspard Gustave de Coriolis who published his formulation in 1835.
|Corrected current||A relatively short series of current observations from a subordinate station from which a factor is applied to adjust the current to a more representative value based on a relatively long series from a nearby control station. (See also current; total current.)||Coastal Engineering|
|Cost analysis||Evaluation of the specific cost elements of a contract to appraise their allowability, allocability, and reasonableness.||Coastal Engineering|
|Cost breakdown||Separating total costs into identifiable elements (e.g., labor materials, equipment, subcontract, overhead, profit, and so forth).||Coastal Engineering|
|Cost||A. Direct cost -(EP 415-1-2) cost of the materials, supplies, equipment, and contractor or sub-contractor work and labor that go into and can be clearly identified with a particular phase of construction, i.e., paving, roofing, etc.|
B. Indirect cost - A cost which cannot be attributed to a single item or unit of construction work.
C. Overhead cost - Indirect costs that are commonly incurred on a project basis and can be attributed directly to the contract, such as maintaining a job office at site. Job overhead differs from direct costs in that job overhead costs are not allocable to a single work item but to several.
|Cotidal hour||The average interval between the Moon's transit over the meridian of Greenwich and the time of the following high water at any place. This interval may be expressed either in solar or lunar time. When expressed in solar time, it is the same as the Greenwich high water interval. When expressed in lunar time, it is equal to the Greenwich high water interval multiplied by the factor 0.966.||Coastal Engineering|
|Cotidal line||A line on a chart or map passing through places having the same cotidal hour.||Coastal Engineering|
|Co-tidal lines||Lines which link all the points where the tide is at the same stage (or phase) of its cycle.||Coastal Engineering|
|Countercurrent||A current usually setting in a direction opposite to that of a main current. (See also Equatorial Countercurrent.)||Coastal Engineering|
|Covalent||Refers to the chemical bond formed by the sharing of one or more electron pairs between two atoms.||Coastal Engineering|
|Cove||A small, sheltered recess in a COAST, often inside a larger EMBAYMENT.||Coastal Engineering|
|Cover layer||The outer layer used in a rubble system as protection against external hydraulic loads.||Coastal Engineering|
|An expression used to indicate an area of a reef or other projection from the bottom of a body of water which periodically extends above and is submerged below the surface.||Coastal Engineering|
|Crater||(Huston. Hydraulic Dredging Principles...) To completely breakdown because of some mechanical or other trouble with the machinery.||Coastal Engineering|
|Creek||1. A stream, less predominant than a river, and generallytributary to a river.|
2. A small tidal channel through a coastal MARSH.
|Creep||Very slow, continuous downslope movement of soil or debris.|
|Crenulate||An indented or wavy shoreline beach form, with the regular seaward- pointing parts rounded rather than sharp, as in the cuspate type.||Coastal Engineering|
|Crest length, wave||The length of a wave along its crest. Sometimes called CREST WIDTH.||Coastal Engineering|
|Crest of berm||The seaward limit of a berm. Also called BERM EDGE.||Coastal Engineering|
|Crest of wave||1. The highest part of a wave.|
2. That part of the wave above still-water level.
|Crest width, wave||See CREST LENGTH, WAVE.||Coastal Engineering|
|Crest||Highest point on a beach face, breakwater, seawall, dam, dike, spillway or weir.||Coastal Engineering|
|Cribbing||Series of structural members laid on top of one another to form a tower supporting a pipeline or other item.||Coastal Engineering|
|Critical flow||The flow regime at a given discharge for which the specific energy (i.e., combination of velocity energy and depth) are a minimum (Froude number = 1). At depths greater than the critical flow depth, the flow is considered to be tranquil or subcritical. At depths less than the critical flow depth, flow is considered to be rapid or supercritical.||Coastal Engineering|
|Critical habitat||(EM 1110-2-5026) Any habitat officially designated or generally accepted as essential to any or all life requirements of an endangered or threatened plant or animal.||Coastal Engineering|
|The minimum amount of shear stress required to initiate substrate particle motion along the stream bed or banks.||Coastal Engineering|
|Cross dike||(EM 1110-2-5026) A dike structure built within a CDF, usually for the purpose of compartmentalizing the CDF for incremental dredging or to improve the efficiency of the CDF.||Coastal Engineering|
|Cross line survey||See cross section hydrographic survey.||Coastal Engineering|
|Cross section||Depicts the shape of the channel in which a stream flows. Measured by surveying the stream bed elevation across the stream on a line perpendicular to the flow. Necessary data for the computation of hydraulic and sediment transport information.||Coastal Engineering|
|Cross-bedding||An arrangement of relatively thin layers of rock inclined at an angle to the more nearly horizontal BEDDING PLANES of the larger rock unit. Also referred to as cross-stratification.||Coastal Engineering|
|Cross-section hydrographic surveys||(ER 1130-2-307) Hydrographic surveys performed normal to channel alignment.||Coastal Engineering|
|Cross-sectional area||1.The area of cross-section below the water surface perpendicular to the direction of flow.|
2.The cross-sectional area is the area of a cross section perpendicular to the direction of flow beneath the water surface.
|Cross-shore||Perpendicular to the SHORELINE.||Coastal Engineering|
|Crown wall||Concrete superstructure on a rubble mound.||Coastal Engineering|
|Crown||The top of a levee.||Coastal Engineering|
|Crushed gravel||Gravel created by the artificial crushing of stone.||Coastal Engineering|
|Cubic feet per second (cfs)||A standard measure of the total amount of water passing by a particular location of a river, canal, pipe or tunnel during a one second interval. One cfs is equal to 7.4805 gallons per second, 28.31369 liters per second, 0.028 cubic meters per second, or 0.6463145 million gallons per day (mgd). Also called second-feet.||Coastal Engineering|
|Culch||Old shells, stones, etc., forming a spawning bed for oysters.||Coastal Engineering|
|Cultural feature||See culture.||Coastal Engineering|
|Culture||Features delineated on a survey, map, or chart which represent objects either constructed by, or resulting from the actions of man; e.g., roads, buildings, canals, piers, etc.||Coastal Engineering|
|Cupola||A small dome-shaped tower or turret rising from a building.||Coastal Engineering|
|Curing||The process of humidity and temperature maintenance performed after concrete placement to assure satisfactory heat of hydration and proper hardening of the concrete.||Coastal Engineering|
|Current constants||Tidal current relations that remain practically constant for any particular locality. Current constants are classified as harmonic and nonharmonic. The harmonic constants consist of the amplitudes and epochs of the harmonic constituents, and the nonharmonic constants include the velocities and intervals derived directly from the current observations.||Coastal Engineering|
|Current curve||A graphic representation of the flow of the current. In the reversing type of tidal current, the curve is referred to rectangular coordinates with time represented by the abscissa and the speed of the current by the ordinate, the flood speeds being considered as positive and the ebb speed as negative. In general, the current curve for a reversing tidal current approximates a cosine curve.||Coastal Engineering|
|Current diagram||A graphic table showing the speeds of the flood and ebb currents and the times of slacks and strengths over a considerable stretch of the channel of a tidal waterway, the times referred to tide or tidal current phases at some reference station.||Coastal Engineering|
|Current difference||Difference between the time of slack water (or minimum current) or strength of current in any locality and the time of the corresponding phase of the tidal current at a reference station for which predictions are given in the Tidal Current Tables.||Coastal Engineering|
|Current direction||See set.||Coastal Engineering|
|Current ellipse||A graphic representation of a rotary current in which the velocity of the current at different hours of the tidal cycle is represented by radius vectors and vectorial angles. A line joining the extremities of the radius vectors will form a curve roughly approximating an ellipse. The cycle is completed in one-half tidal day or in a whole tidal day, according to whether the tidal current is of the semidiurnal or the diurnal type. A current of the mixed type will give a curve of two unequal loops each tidal day.||Coastal Engineering|
|Current hour||The mean interval between the transit of the Moon over the meridian of Greenwich and the time of strength of flood, modified by the times of slack water (or minimum current) and strength of ebb. In computing the mean current hour, an average is obtained of the intervals for the following phases - flood strength, slack (or minimum) before flood increased by 3.10 hours (one-fourth of tidal cycle). Before taking the average, the four phases are made comparable by the addition or rejection of such multiples of 12.|
42 hours as may be necessary. The current hour is usually expressed in solar time, but if the use of lunar time is desired, the solar hour should by multiplied by the factor 0.966.
|Current line||A graduated line attached to a current pole used in measuring the velocity of the current. The line is marked in such a manner that the speed of the current, expressed in knots and tenths, is indicated directly by the length of line carried out by the current pole in a specified interval of time. When marked for a 60-second run, the principal divisions for the whole knots are spaced at 101.33 feet and the subdivisions for tenths of knots are spaced at 10.13 feet.||Coastal Engineering|
|Current meter||An instrument for measuring the velocity of a current||Coastal Engineering|
|Current pole||A pole used in observing the velocity of the current. The pole formerly used by the Coast and Geodetic Survey was about 3 inches in diameter and 15 feet long, and was weighted at one end to float upright with the top about 1 foot out of water. Shorter poles were used when necessary for shallow water. In use, the pole is attached to the current line but separated from the graduated portion by an ungraded section of approximately 100 feet, known as the stray line. As the pole is carried out from an observing vessel by the current, the amount of line passing from the vessel during a specific time interval indicates the speed of the current.|
The set is obtained from a relative bearing from the vessel to the pole. The bearing is then related to the ship's compass and converted to true.
|Current station||The geographic locations at which current observations are conducted. Also, the facilities used to make current observations. These may include a buoy, ground tackle, current meters, recording mechanism, and radio transmitter.||Coastal Engineering|
|Current system, nearshore||See NEARSHORE CURRENT SYSTEM.||Coastal Engineering|
|Current, coastal||One of the offshore currents flowing generally parallel to the shoreline in the deeper water beyond and near the surf zone; these are not related genetically to waves and resulting surf, but may be related to tides, winds, or distribution of mass.||Coastal Engineering|
|Current, drift||A broad, shallow, slow-moving ocean or lake current. Opposite of CURRENT, STREAM.||Coastal Engineering|
|Current, ebb||The tidal current away from shore or down a tidal stream. Usually associated with the decrease in the height of the tide.||Coastal Engineering|
|Current, eddy||See EDDY.||Coastal Engineering|
|Current, feeder||Any of the parts of the nearshore current system that flow parallel to shore before converging and forming the neck of the RIP CURRENT.||Coastal Engineering|
|Current, flood||The tidal current toward shore or up a tidal stream. Usually associated with the increase in the height of the tide.||Coastal Engineering|
|Current, inshore||See INSHORE CURRENT.||Coastal Engineering|
|Current, littoral||Any current in the littoral zone caused primarily by wave action; e.g., LONGSHORE CURRENT, RIP CURRENT.||Coastal Engineering|
|Current, longshore||The littoral current in the breaker zone moving essentially parallel to the shore, usually generated by waves breaking at an angle to the shoreline.||Coastal Engineering|
|Current, nearshore||A current in the NEARSHORE ZONE.||Coastal Engineering|
|Current, offshore||See OFFSHORE CURRENT.||Coastal Engineering|
|Current, periodic||See CURRENT, TIDAL.||Coastal Engineering|
|Current, permanent||See PERMANENT CURRENT.||Coastal Engineering|
|Current, rip||See RIP CURRENT.||Coastal Engineering|
|Current, stream||A narrow, deep, and swift ocean current, as the Gulf Stream. CURRENT, DRIFT.||Coastal Engineering|
|Current, tidal||The alternating horizontal movement of water associated with the rise and fall of the tide caused by the astronomical tide-producing forces. Also CURRENT, PERIODIC.||Coastal Engineering|
|Current||1. The flowing of water, or other liquid or gas.|
2. That portion of a stream of water which is moving with a velocity much greater than the average or in which the progress of the water is principally concentrated.
3. Ocean currents can be classified in a number of different ways. Some important types include the following:
-Periodic - due to the effect of the tides; such Currents may be rotating rather than having a simple back and forth motion. The currents accompanying tides are known as tidal currents
-Temporary - due to seasonal winds
-Permanent or ocean - constitute a part of the general ocean circulation. The term DRIFT CURRENT is often applied to a slow broad movement of the oceanic water
-Nearshore - caused principally by waves breaking along a shore.
|Current-refraction||Process by which wave velocity, height, and direction are affected by a current||Coastal Engineering|
|Curve widener||See fillet.||Coastal Engineering|
|Curved element side||An optional aesthetic means to outline key landmarks within the computational domain. A quadratic curved side is created by assigning (x, y) coordinates to the mid-side node of an element.||Coastal Engineering|
|Cusp||One of a series of short ridges on the FORESHORE separated by crescent-shaped troughs spaced at more or less regular intervals. Between these cusps are hollows. The cusps are spaced at somewhat uniform distances along beaches. They represent a combination of constructive and destructive processes. Also BEACH CUSP.||Coastal Engineering|
|Cuspate bar||A crescent-shaped bar uniting with the shore at each end. It may be formed by a single spit growing from shore and then turning back to again meet the shore, or by two spits growing from the shore and uniting to form a bar of sharply cuspate form.||Coastal Engineering|
|Cuspate foreland||The largest cusp, occurring as a cape or as a broadly triangular point of sand or shingle, with the apex pointing seaward, along an open coast. On some coasts, cuspate forelands measure many kilometers from apex to apex and extend seaward for several kilometers. They are formed by the convergence of regional littoral drift systems, or by the progradation of cuspate bars. Examples: Cape Canaveral, Florida and Cape Hatteras, North Carolina.||Coastal Engineering|
|Cuspate spit||The spit that forms in the lee of a shoal or offshore feature (BREAKWATER, island, rock outcrop) by waves that are refracted and/or diffracted around the offshore feature. It may eventually grow into a TOMBOLO linking the feature to the mainland.||Coastal Engineering|
|Cut bank||The outside, often eroding, bank on a channel bend. Typically opposite a Point Bar.||Coastal Engineering|
|Cut sheet||A pictorial representation of a plan for dredging in a selected location.||Coastal Engineering|
|Cut stakes||Boards or bars placed into the ground to physically lay out a planned dredging operation.||Coastal Engineering|
|Cut water||A protrudence within a pump shell that separates the volute from the discharge.||Coastal Engineering|
|Cut||Excavation made by a dredge during a swing or pass of the dredge. a. box, dredging a rectangular section in lieu of slope cutting. The width of the cut is sufficient to allow the slopes to cave to the natural underwater repose of the material without encroaching the desired channel dimensions. b. slope, dredging the slope in place as opposed to box cutting. More care is taken with the use of gyro compasses and electronic positioning equipment where exact slopes are required.|
|Cutoff island||An island created in a bend or meander by excavating a bypass or diversion channel across the meander neck.||Coastal Engineering|
|Cutoff||An impervious construction placed beneath a dam to intercept seepage flow.||Coastal Engineering|
|Cuttability||The relative ease with which a sediment can be excavated by shearing with a blade, knife, or plow.||Coastal Engineering|
|Cutter drive motor||See cutter motor.||Coastal Engineering|
|Cutter motor||A comparatively small and powerful engine connected to the cutter by a shaft, which is utilized to rotate the cutter during dredging operations.||Coastal Engineering|
|Cutter shaft||A rotating driveline for transmitting motion from the cutter motor to the cutter.||Coastal Engineering|
|Cutterhead dredge||A hydraulic dredge that uses a rotating steel head consisting of hardened cutting blades and a backing ring to dislodge bottom material. The head is mounted at the suction entrance of the hydraulic pipeline, and fluidized material is picked up by suction and carried away through the pipe.||Coastal Engineering|
|Cutterhead||A rotating device consisting of cutting blades, backing ring, used at the suction entrance of a hydraulic pipeline dredge to dislodge bottom material, which is then picked up by suction. |
a. basket -a cutterhead design incorporating a front hub, a back wearing ring, and several spiral shaped blades integral with the hub and ring.
b. open-nose -a type of cutterhead with blades well spaced to prevent clogging, that is suitable for clay or hard materials.
c. removable tooth -a cutterhead whose teeth can be removed and replaced.
d. matchbox -(See Palermo for definition)
|Cutting width||The swath of the dustpan, draghead or various mechanical dredge tools while moving through the material being dredged. For a cutterhead dredge which cuts an arc, it is the effective channel width that can be achieved in making its swing.||Coastal Engineering|
|Cyanobacteria||Bluegreen algae; phylum or organisms that are biochemically bacterial in nature but perform plant photosynthesis.||Coastal Engineering|
|Cycle slip||A discontinuity in the measured carrier beat phase resulting from a temporary loss-of-lock in the carrier tracking loop of a GPS receiver.||Coastal Engineering|
|Cycloidal wave||A steep, symmetrical wave whose crest forms an angle of 120 degrees and whose form is that of a cycloid. A trochoidal wave of maximum steepness.||Coastal Engineering|
|Cyclone||A system of winds that rotates about a center of low atmospheric pressure. Rotation is clockwise in the Southern Hemisphere and anti-clockwise in the Northern Hemisphere. In the Indian Ocean, the term refers to the powerful storms called HURRICANES in the Atlantic.||Coastal Engineering|
back to top
Structure built in rivers or estuaries, basically to separate water at both sides and/or to retain water at one side.
The increased cost to a contractor resulting from government acts or omissions affecting the contract but not incorporated into a change order. The value of the loss to the government resulting from contractor acts or omissions.
|Damping ratio||The ratio of the actual damping to the critical damping, critical damping being the minimum amount of damping that prevents free oscillatory vibration.||Coastal Engineering|
|Damping||Resistance that reduces vibration by energy absorption. There are different types of damping such as viscous and Coulomb damping.||Coastal Engineering|
|Danforth anchor||See anchor.||Coastal Engineering|
|Darcy's law||An empirical equation developed to compute the quantity of water flowing through an aquifer.||Coastal Engineering|
|Data message||A message included in the GPS signal which reports the satellite's location, clock correlations and health. Included is rough information on the other satellites in the constellation.||Coastal Engineering|
|Data||In quality assurance, measurements collected for a planned purpose and suitable for the inference of conclusions.||Coastal Engineering|
|Datum (vertical), as in marine|
A base elevation used as a reference from which to reckon heights or depths. It is called a tidal datum when defined in terms of a certain phase of the tide. Tidal datums are local datums and should not be extended into areas which have differing hydrographic features without substantiating measurements. In order that they may be recovered when needed, such datums are referenced to fixed points known as bench marks.
|Datum plane||(NAVFAC. DM-26.3) The horizontal plane to which soundings, ground elevations, or water-surface elevations are referred. The plane is called a Tidal Datum when defined by a certain phase of the tide.||Coastal Engineering|
|Datum, chart||See CHART DATUM.||Coastal Engineering|
The horizontal plane to which soundings, ground elevations, or water surface elevations are referred. Also REFERENCE PLANE. The plane is called a TIDAL DATUM when defined by a certain phase of the tide. The following datums are ordinarily used on hydrographic charts:MEAN LOW WATER--Atlantic coast (U. S.), Argentina, Sweden, and Norway. MEAN LOWER LOW WATER--Pacific coast (U. S.). MEAN LOW WATER SPRINGS--United Kingdom, Germany, Italy, Brazil, and Chile. LOW WATER DATUM--Great Lakes (U. S. and Canada).
LOWEST LOW WATER SPRINGS--Portugal. LOW WATER INDIAN SPRINGS--India and Japan (See INDIAN TIDE PLANE). LOWEST LOW WATER--France, Spain, and Greece. A common datum used on United States topographic maps is MEAN SEA LEVEL.
|Datum||Any permanent line, plane or surface used as a reference datum to which elevations are referred.See datum plane.||Coastal Engineering|
|Davidson current||Deep-ocean boundary current off the west coast of the U.S. which brings warmer, saltier, low oxygen, high phosphate equatorial type water from low to high latitudes.||Coastal Engineering|
|Davis-Bacon act||A law requiring that all wages paid under Federal contracts are not less than the scale determined by the Department of Labor to be representative for the region. For dredges, this applies only to those actively involved in dredging and not those transporting dredged materials.||Coastal Engineering|
|Davit||Light duty boom, usually a pair, used to deploy launch or lifeboat from mother vessel.||Coastal Engineering|
|Day of the year||The sequentially numbered day of the year.||Coastal Engineering|
|Day||The period of rotation of the Earth. There are several kinds of days depending on whether the Sun, Moon, or other object or location is used as the reference for the rotation.||Coastal Engineering|
|Daybeacon||An unlighted structure which serves as a daytime aid to navigation by virtue of its distinctive appearance which makes it recognizable and identifiable.||Coastal Engineering|
|Daylight saving time||A time used during the summer months, in some localities, in which clocks are advanced 1 hour from the usual standard time.||Coastal Engineering|
|Daymark||The identifying characteristics of an aid to navigation, unique and distinctive to facilitate its daytime recognition. Also, a conspicuous target added to a daybeacon or light.||Coastal Engineering|
|Dead load||The constant load on the dam resulting from the mass of the concrete and other attachments.||Coastal Engineering|
|Dead storage||The portion of a storage basin or reservoir that cannot be use for temporary water storage.||Coastal Engineering|
|Deadhead||1. A submerged or barely awash log or tree trunk freely floating at varying attitudes vis-a-vis the plane formed by the still (undisturbed) surface of the water. At times, one end of a deadhead may become temporarily attached to the bottom with the opposite (unattached) end floating in a pivotal or vertical manner due to the action of waves and/or currents. The existence of freely floating; i.e., unattached deadheads should be noted in the survey records.|
2. In hydrographic surveying, time spent running a ship or launch during which no productive survey work is accomplished;e.g., running to and from the working grounds.
3. (Pop culture) A devoted fan of the band The Grateful Dead, whose music can sometimes be heard on waterborne vessels.
|Debris basin||A basin constructed to trap sediment or debris that would clog or damage a flood channel.||Coastal Engineering|
|Debris line||A line near the limit of storm wave uprush marking the landward limit of debris deposits.||Coastal Engineering|
|Debris||Inorganic sediment or trash such as tires of shopping carts.||Coastal Engineering|
|Decay area||Area of relative CALM through which waves travel after emerging from the generating area.||Coastal Engineering|
|Decay distance||The distance waves travel after leaving the generating area (FETCH).||Coastal Engineering|
|Decay of waves||The change waves undergo after they leave a generating area (FETCH) and pass through a calm, or region of lighter winds. In the process of decay, the significant wave height decreases and the significant wavelength increases.||Coastal Engineering|
|Decay rate||The measured breakdown of a constituent over time. Unit = 1/Time||Coastal Engineering|
|Decibar||The practical unit for pressure in the ocean, equal to 10 centibars.||Coastal Engineering|
|Deck captain||A supervisory employee directly responsible for the outside operations of the dredge as contrasted to the inside activities such as the engine room, lever room or galley. He directs the mates, deckhands, boat operators and any other operators of deck equipment, machinery, and ancillary floating plant in conjunction with the needs of the leverman.||Coastal Engineering|
|Declination||Angular distance north or south of the celestial equator, taken as positive when north and negative when south of the equator.|
The Sun passes through its declination cycle once a year, reaching its maximum north declination of approximately 23 1/2 degrees about June 21 and its maximum south declination of approximately 23 1/2 degrees about December 21. The Moon has an average declination cycle of 27 1/3 days which is called a tropical month.
Tides or tidal currents occurring near the time of maximum north or south declination of the Moon are called tropic tides or tropic currents, and those occurring when the Moon is over the equator are called equatorial ties or equatiorial currents.
The maximum delcination reached by the Moon in sucessive months depends upon the longitude of the Moon's node, and varies from 28 1/2 degrees when the longitude of the ascending node is 0 degrees, to 18 1/2 degrees when the longitude of the node is 180 degrees. The node cycle, or time required for the noe to complete a circuit of 360 degrees of longitude, is approximately 18.6 years.
|Declinational inequality||See diurnal inequality.||Coastal Engineering|
|Declinational reduction||A processing of observed high and low waters or flood and ebb tidal currents to obtain quantities depending upon changes in the declination of the Moon, such as tropic ranges or speeds, height or speed inequalities, and tropic intervals.||Coastal Engineering|
|Decomposition||The breakdown of organic matter by bacteria and fungi.||Coastal Engineering|
|Deep water waves||A wave in water the depth of which is greater than one-half the WAVE LENGTH.||Coastal Engineering|
|Deep water||Water so deep that surface waves are little affected by the ocean bottom. Generally, water deeper than one-half the surface wavelength is considered deep water. Compare SHALLOW WATER.||Coastal Engineering|
|Deep-draft navigation project, navdat||The traditional distinction between shallow and deep draft waterway and channel projects is fourteen feet. Projects which have a depth of fourteen feet or less are considered shallow draft; those greater than fourteen feet are considered deep draft. An exception to the depth definition is for a project with an authorized depth greater than fourteen feet, but only at the open water entrance channel for access to a channel of fourteen feet or less. Such a project is treated as a shallow draft project.||Coastal Engineering|
|Deep-draft port||A seaport that is accessible to seagoing ships, i.e., it has water depths in harbor channels and at marine terminal facilities capable of accommodating deep-draft oceangoing vessels.||Coastal Engineering|
|Deepening project||(EM 1110-2-1003) Authorized construction for deepening an existing project.||Coastal Engineering|
|Defect||In quality assurance, a failure to comply with specified quality requirements for visual, dimensional, or physical characteristics.||Coastal Engineering|
|Defense contract audit agency, dcaa||The government agency that performs external audits for Corps of Engineers contracts (military only).||Coastal Engineering|
|Deflation||a )The removal of loose material from a beach or other land surface by wind action.|
b )The sorting out, lifting, and removal of loose dry fine-grained particles (clay and silt sizes) by the turbulent eddy action of the wind, as along a sand-dune coast or in a desert; a form of wind erosion.
|Deflection||Linear deviation of the structure due to the effect of loads or volumetric changes.||Coastal Engineering|
|Deformation||Alteration of shape or dimension due to stress.||Coastal Engineering|
|Degassing||The act of removing gases released from dredged sediments from the suction line of a hydraulic dredge. See gas ejectors.||Coastal Engineering|
|Degradation||The geologic process by which stream beds, floodplains, and the bottoms of other water bodies are lowered in elevation by the removal of material from the boundary. It is the opposite of aggradation.||Coastal Engineering|
|Degree of saturation||(ASTM D 653) The extent or degree to which the voids in rock contain fluid (water, gas, or oil). Usually expressed in percent related to total void or pore space.||Coastal Engineering|
|Delay||A significant slowing down or stopping of a contractor's scheduled progress in completing work required under a contract. This may be caused by acts of the government or contractor, or from something beyond the control of either, and may be either excusable or non-excusable.||Coastal Engineering|
|Delta plain||he nearly-level surface composing the landward portion of a large DELTA.||Coastal Engineering|
|Delta time step||The increment of prototype time between two time steps.||Coastal Engineering|
|Delta||A deposit of sediment formed where moving water (as from a stream at its mouth) is slowed by a body of standing water.||Coastal Engineering|
|Deltaic||Pertaining to river deltas||Coastal Engineering|
|Demobilization||The process of disassembling and transporting all dredging equipment from the dredging site.||Coastal Engineering|
|Dendrochronology||The examination and correlation of growth rings of trees with the purpose of dating events in the recent past.||Coastal Engineering|
|Denitrification||Anaerobic bacterial process metabolism in which nitrate is used instead of oxygen during the oxidation of organic carbon compounds to yield energy (respiration). The process oxidizes organic carbon and (chemically) reduces nitrate to the gaseous end products N2 (nitrogen gas) or N2O (nitrous oxide). This is the major process used in wastewater treatment plants to ultimately convert combined nitrogen to a non-polluting state.||Coastal Engineering|
|Density Current||A highly turbid mixture of water and very fine grained sediment which flows into and along the bottom of a reservoir because its density is relatively larger than that of the standing water in the reservoir.||Coastal Engineering|
|Density flow||A flow caused by differences in densities of fluids.||Coastal Engineering|
|Density meter||A device that measures parameters related to the bulk density, or bulk unit weight, of the dredged slurry in a pipeline.||Coastal Engineering|
|Density Stratification||Creation of layers in a water body due to density differences; controlled by temperature, dissolved solids concentration and particle concentration.||Coastal Engineering|
|Density, in situ (s.t.p.)||Mass per unit volume. The reciprocal of specific volume. as in oceanography, the density of sea water is numerically equivalent to specific gravity and is a function of salinity, temperature, and pressure.||Coastal Engineering|
|Density||The mass of a substance per unit volume. The Greek letter r is the common symbol.||Coastal Engineering|
|Density-driven circulation||Variations in salinity create variations in density in estuaries. These variations in density create horizontal pressure gradients, which drive estuarine circulation.||Coastal Engineering|
|Deposit||In geology, a limited, contiguous quantity of soil or rock of essentially uniform composition and produced by essentially the same deposition process.||Coastal Engineering|
|Deposition basin||A dredged area, sometimes located downdrift of a weir jetty, specifically designed to capture sediment so that shoaling in navigable regions (e.g., the channel) will be minimized.||Coastal Engineering|
|Deposition||The mechanical or chemical processes through which sediments accumulate in a (temporary) resting place. The raising of the stream bed by settlement of moving sediment that may be due to local changes in the flow, or during a single flood event.||Coastal Engineering|
|Depositional topography||Topography formed as a result of sediments being dropped from a moving medium (e.g., sand ridges or sand dunes).||Coastal Engineering|
|Depression||A general term signifying any depressed or lower area in the ocean floor.||Coastal Engineering|
|Depth contour||See CONTOUR, also ISOBATH.||Coastal Engineering|
A line on a map, hydrographic survey, or nautical chart drawn in accordance with prescribed conventions and connecting points of equal depth at or below a specified sounding datum. -"Depth curve" is the accepted expression and should be used in lieu of "depth contour".
|Depth digitizer||See digitizer.||Coastal Engineering|
|Depth factor||See SHOALING COEFFICIENT.||Coastal Engineering|
|Depth finder||A machine that uses sound waves to indicate and/or record the water depth or distance between vessel hull and bottom. The electronic device measures the elapsed times of acoustical pulses and converts these times to depth.||Coastal Engineering|
|Depth gauge||See depth finder.||Coastal Engineering|
|Depth indicator||See depth finder.||Coastal Engineering|
|Depth integrating, suspended-sediment sampler||An instrument designed to be lowered to within a few inches of the stream bed while collecting a watersediment mixture isokinetically into a bottle. Sampling starts automatically as the instrument enters the water and continues until the orifice breaks the water surface on the return trip from the bed. Hence, a sampler suitable for performing depth integration.||Coastal Engineering|
|Depth of breaking||The still-water depth at the point where a wave breaks.Also BREAKER DEPTH.||Coastal Engineering|
|Depth of Flow||The depth of flow is the vertical distance from the bed of a stream to the water surface.||Coastal Engineering|
|Depth, as in measured depth||A. bucket-water surface to bottom-most lip of bucket while excavating.|
B. draghead -water surface to bottom of grate on draghead.
D. cutter -water surface to extreme low point of cutter tooth blade while excavating.
|Depth, controlling||See CONTROLLING DEPTH.||Coastal Engineering|
|Depth||The vertical distance from a specified datum to the sea floor.||Coastal Engineering|
|Depth-integrated sample||A sample of the water-sediment mixture collected at a vertical in accordance with the technique of depth integration. The sample is used to determine the sediment discharge and the range of particle sizes in that discharge, i.e. the sediment load in that discharge.||Coastal Engineering|
A method of sampling the water-sediment mixture in a flowing stream whereby the sampling instrument is lowered down to the bottom and returned to the surface in a continuous motion and at the proper rate to collect a discharge-weighted sample of the mixture. Ordinarily, depth integration is performed by traversing the water column with a depthintegrating sampler. However, when the water is so deep or the current is so swift that a single bottle cannot contain the entire sample, depth-integration is accomplished by partitioning the water column into layers, vertically, and lowering a point-integrating sampler through each layer separately.
The valve on the point sampler allows the inflow orifice to be opened only for the layer being sampled. Depth integration has also been accomplished using a vertical-slot sampler.
|Derelict||A vessel or any property abandoned and afloat at sea and thereby constituting a real or potential danger to navigation.||Coastal Engineering|
|Derrick barge||See barge.||Coastal Engineering|
|Derrick stone||See STONE, DERRICK.||Coastal Engineering|
|Design change||A change for which redesign effort is required. A design change materially affects the approved requirements, the basis of design, the existing scope of the contract plans and specifications, or operating capability of the facility.||Coastal Engineering|
|Design flood||The maximum amount of water for which a flood control project will offer protection. Selection is based on engineering, economic and environmental considerations. (USACE)||Coastal Engineering|
|Design hurricane||See HYPOTHETICAL HURRICANE.||Coastal Engineering|
|Design response spectra||Smooth, broad-banded spectra appropriate for specifying the level of seismic design force, or displacement, for earthquake-resistant design purposes.||Coastal Engineering|
|Design ship||A ship or tow whose dimensions are used in designing a particular channel.||Coastal Engineering|
A hypothetical extreme storm whose waves coastal protection structures will often be designed to withstand. The severity of the storm (i.e. return period) is chosen in view of the acceptable level of risk of damage or failure. A DESIGN STORM consists of a DESIGN WAVE condition, a design water level and a duration.
|Design wave condition||Usually an extreme wave condition with a specified return period used in the design of coastal works.||Coastal Engineering|
|Design wave||In the design of HARBORS, harbor works, etc., the type or types of waves selected as having the characteristics against which protection is desired.|
|Designated use||Classification designated in water quality standards for each water body or segment that defines the optimal purpose for that water body.|
|Destructive wave||A wave that erodes a beach by moving material seaward, as a storm wave with a more powerful backrush than uprush; on a sandy beach, a wave with a steepness greater than 0.25.||Coastal Engineering|
|Detached breakwater||A BREAKWATER without any SUBAERIAL connection to the shore.||Coastal Engineering|
|Detention||Water management practice or system that delays the downstream progress of storm water by the use of temporary storage or metered outlets.||Coastal Engineering|
|Deterministic Model||Mathematical model in which the behavior of every variable is completely determined by the governing equations and the initial states of the variables.||Coastal Engineering|
|Detritus||Dead or decaying organic matter; technically called organic detritus to distinguish it from the mineral detritus classified by geologists.||Coastal Engineering|
|deviation (of compass)|
The deflection of the needle of a magnetic compass due to masses of magnetic metal within a ship on which the compass is located. This deflection varies with different headings of the ship. The deviation is called easterly and is marked plus if the deflection is to the right of magnetic north, and is called westerly and marked minus if it is to the left of magnetic north. A deviation table is a tabular arrangement showing the amount of deviation for different headings of the ship. Each compass requires a separate deviation table.
|Dewatering||(ER 1110-2-5025, WES TR DS-78-11) The process of active or passive removal of water from dredged material placed in a confined disposal facility. The purpose of dewatering is to consolidate the dredged material. Used in conjunction with other site management techniques to increase future storage volume of the facility as well as to improve foundation properties. Examples of dewatering techniques include trenching and underdrainage. (See also consolidation; dragline trenching; progressive trenching; underdrainage.)||Coastal Engineering|
|Diameter, standard fall||See standard fall diameter.||Coastal Engineering|
|Diameter, standard sediment||See standard sedimentation diameter.||Coastal Engineering|
|Diaphone||A sound signal which produces sound by means of a slotted piston moved back and forth by compressed air. A "two-tone" diaphone produced two sequential tones with the second tome of lower pitch.||Coastal Engineering|
|Diatom||Group of algae characterized by glass (silica) cell wall, beautifully ornamented; often the brown stuff attached to rock surfaces.||Coastal Engineering|
|Diel||A 24 hour period of time.||Coastal Engineering|
|Differential chart||Chart depicting the (depth) differences|
a) between different levels (e.g., 210 kHz-density measured at the same time;
b) between the levels indicating the same parameter, measured at different times.
|Differential compaction||A kind of compaction produced by uneven settling of homogeneous earth material under the influence of gravity (as where thick sediments in depressions settle more rapidly than thinner sediments on hilltops) or by differing degrees of compactability of sediments (as where clay loses more interstitial water and comes to occupy less volume than sand).||Coastal Engineering|
|Differential erosion / weathering|
These features develop in rocks which have varying resistance to the agencies of erosion and/or weathering so that parts of the rock are removed at greater rates than others. A typical example is the removal of soft beds from between harder beds in a series of sedimentary rocks. The term may be applied to any size of feature, from small-scale 'etching' to the regional development of hills and valleys controlled by hard and soft rocks.
|Differential global positioning system, dgps||Precise measurements of the relative positions of two receivers tracking the same GPS signals.||Coastal Engineering|
|Differential leveling||(EM 1110-2-1003) Conventional terrestrial leveling using spirit bubble or self-compensating instruments.||Coastal Engineering|
|Differential settlement||Nonuniform settlement; the uneven lowering of different parts of an engineering structure, often resulting in damage to the structure.||Coastal Engineering|
|Differing site conditions|
Refers to subsurface or latent physical conditions at the site differing materially from those indicated in the contract. Unknown physical conditions at the site, of an unusual nature, differing materially from those ordinarily encountered and generally recognized as inherent in work of the character provided for in the contract are also included in this clause.
|Diffraction (of water waves)||The phenomenon by which energy is transmitted laterally along a wave crest. When a part of a train of waves is interrupted by a barrier, such as a BREAKWATER, the effect of diffraction is manifested by propagation of waves into the sheltered region within the barrier's geometric shadow.||Coastal Engineering|
|Diffraction coefficient||Ratio of diffracted wave height to DEEPWATER wave height.||Coastal Engineering|
|Diffuser||A device placed on the end of a discharge pipeline to slow the velocity of discharged material, thereby providing better control over point disposal and reducing turbidity and water column impacts. (Consider different types of diffusers via Aidala)||Coastal Engineering|
The movement of a substance from an area of high concentration to an area of low concentration. Turbulent diffusion, or mixing, results from atmospheric motions (wind) diffusing water, vapor, heat, and other chemical components by exchanging parcels called eddies between regions in space in apparent random fashion. Molecular diffusion, which operates in stagnant zones, such as at the bottom sediment-water boundary in a deep lake, occurs much, much more slowly and so is important only on a very small scale such as right at the bottom.
|Diffusivity||The ratio of transmissivity to storage coefficient in an aquifer.||Coastal Engineering|
|Digging depth||The vertical distance from the water surface down to the bottom of the cutter, dustpan, draghead or other digging apparatus.||Coastal Engineering|
|Digging spud||See spud.||Coastal Engineering|
|Digging swing||The rotation or swing of the cutterhead dredge while pivoting on the digging spud with the cutter cutting into and under the material, lifting it up and into the suction mouth.||Coastal Engineering|
|Digital depth recorder||A digital depth finder.||Coastal Engineering|
|Digital distance measuring unit||In hydrographic survey, an electronic device used to measure distances which uses digital technology.||Coastal Engineering|
|Digital tide gage||See automatic tide gage.||Coastal Engineering|
1. The representation of integers in a number system. The term is generally used to indicate data conveyed in a purely numerical form to permit the manipulation by automated techniques and procedures.
2. Pertaining to the utilization of discrete integral numbers in a given base to represent all the quantities that occur in a problem or a calculation. It is possible to express in digital form all information stored, transferred, or processed by a dual state condition; e.g., on-off, open-closed, and true-false.
|Digitization||Representation of a continuous process, field, or surface by numerical (digital) values.||Coastal Engineering|
|Digitize||To convert data from map or graphical form to digital form for use by computer programs.||Coastal Engineering|
|Digitizer||(EM 1110-2-1003) A device that converts analog signals to digitized signals.||Coastal Engineering|
The process of electronically capturing key points on a map, using a digitizing table and a pointing device. The points are captured in an x, y plane, with a z (depth) value usually associated with each point. The points can be displayed on a computer screen, and can be used as a basis for mesh creation.
|Dike||1. Earth structure along sea or river in order to protect low lands from flooding by high water; dikes along rivers are sometimes called LEVEES. Sometimes written as DYKE.|
2. A wall or mound built around a low-lying area to prevent flooding.
|Diked disposal facility||See confined disposal area.||Coastal Engineering|
|Dilution of precision||The multiplicative factor that modifies ranging error. It is caused solely by the geometry between the user and his set of satellites. Known as DOP or GDOP.||Coastal Engineering|
A physically meaningful ratio of parameters that is dimensionless. These dimensionless ratios are useful in determining scaling laws since a particular dimensionless number must be the same in both model and prototype to achieve similarity. Examples are the common force ratios, such as the Froude and Reynolds numbers.
|Dimictic||Having two mixing periods, typically in spring and fall.||Coastal Engineering|
|Dipole - Dipole Forces|
|Intermolecular attraction between the oppositely charged poles of nearby molecules.||Coastal Engineering|
|Dipole - Induced Dipole Forces||Very weak forces between a dipole and non-polar molecule that acts like a dipole in the presence of a dipole molecule.||Coastal Engineering|
|Dipole||A molecule that has two opposite electrical poles, or regions, separated by a distance.||Coastal Engineering|
|Dipper dredge||See dredge, mechanical, cable excavator, dipper.||Coastal Engineering|
|Dipteran||True flies.||Coastal Engineering|
|Direct costs||Costs to the prime contractor for materials, labor, equipment and subcontracts that go into, and can be clearly identifiable to, a particular feature of work.||Coastal Engineering|
Alternative to bottom gravity disposal in which the loaded hopper dredge ties up to a specially constructed dock or shore facility, hooks up to discharge pipeline and uses hopper dredge pumps to transfer dredge material into a confined disposal facility.
|Direct shear test||(ASTM D 653) A shear test in which soil or rock under an applied normal load is stressed to failure by moving one section of the sample or sample container (shear box) relative to the other section.||Coastal Engineering|
|Direction of current||See set.||Coastal Engineering|
|Direction of wind||Direction from which the wind is blowing.||Coastal Engineering|
|Dirichlet condition||Also known as a constant head boundary. A boundary condition for a groundwater computer model where the head is known at the boundary of the flow field.||Coastal Engineering|
|Discharge area||An area in which there are upward components of hydraulic head in the aquifer.||Coastal Engineering|
|Discharge boom||A boom used on a hopper or side-casting dredge to support the discharge line enabling the spoils to be discharged a distance from the side of the cut.||Coastal Engineering|
|Discharge head||The sum of the static, velocity, and friction energy in a discharge system, usually expressed in feet.||Coastal Engineering|
|Discharge of dredged material|
(33 CFR 323.2(d)) Any addition of dredged material into waters of the United States (pursuant to Clean Water Act Section 404(b)(1) Guidelines). The term includes, without limitation, the addition of dredged material to a specified discharge site located in waters of the United States and the runoff or overflow from a contained land or water disposal site.
|Discharge pipe||See pipe.||Coastal Engineering|
|Discharge pressure||The pressure (pounds per square inch or feet of fresh water above atmospheric pressure) in the pump's discharge line on the pump side of the flap valve.||Coastal Engineering|
|Discharge turbidity||See turbidity.||Coastal Engineering|
|Discharge wye valve|
A valve placed in the shore pipeline located at or near the discharge into the disposal area, used to provide two outlet possibilities (i.e., when pipe are to be added, one leg of the wye can be closed, stopping flow in that leg but allowing the flow to continue through the other leg thereby allowing the dredge to continue pumping.)
|Discharge||The discharge, usually abbreviated as "Q", is the volume of a fluid or solid passing a cross section of a stream per unit time.||Coastal Engineering|
|Discharge-weighted concentration||The dry mass (weight) of sediment in a unit volume of stream discharge, or the ratio of the mass discharge (dry) of sediment to the mass discharge of water-sediment mixture.||Coastal Engineering|
|Discretization Error||Error introduced by the discrete representation of a continuous variable.||Coastal Engineering|
|Discretization||The procedure of representing a continuous variable by discrete values at specified points in space and/or time.||Coastal Engineering|
|To de-flocculate or disaggregate compound particles, such as clays and fine silts, into individual component particles (ultimate particles).||Coastal Engineering|
|Dispersed system||A condition in particle-size analyses whereby particles begin to settle from an initial uniform dispersion, such that particles of equivalent fall diameters settle at the same rate.||Coastal Engineering|
1. Pattern of geographic distribution of individuals within a species.
2. Distortion of the shape of a seismic wave train or ocean wave train because of variations of velocity with frequency.
3. The phenomenon by which a solute in flowing groundwater is mixed with uncontaminated water and becomes reduced in concentration. Dispersion is caused by differences in the velocity that the water travels at the pore level and differences in the rate at which water travels through different strata in the flow path.
|Disposal alternative||See preferred placement alternative; placement alternative.|
|Disposal area||See preferred placement alternative; placement alternative.||Coastal Engineering|
|Disposal site or disposal area|
A precise geographical area within which disposal of dredged material occurs. (404 Manual) That portion of the "Waters of the United States" where specific disposal activities are permitted. It consists of a bottom surface area and any overlying volume of water. In the case of wetlands on which surface water is not present, the disposal site consists of the wetland surface area. [Note - Upland locations, although not mentioned in this definition in the Regulations, can also be disposal sites].
|Disposal site||See placement site.||Coastal Engineering|
|Dispute||A disagreement as to a question of fact or contract interpretation which cannot be resolved to the mutual satisfaction of the contracting parties.||Coastal Engineering|
|Dissolved load||The part of the stream load that is carried in solution, such as chemical ions yielded by weathering and erosion of the land mass.||Coastal Engineering|
|Dissolved Oxygen (DO or O2)|
The concentration of free (not chemically combined) molecular oxygen (a gas) dissolved in water, usually expressed in milligrams per liter, parts per million, or percent of saturation. Adequate concentrations of dissolved oxygen are necessary for the life of fish and other aquatic organisms and the prevention of offensive odors. DO levels are considered the most important and commonly employed measurement of water quality and indicator of a water body's ability to support desirable aquatic life.
Levels above 5 milligrams per liter (mg O2/L) are considered optimal and most fish cannot survive for prolonged periods at levels below 3 mg O2/L. Levels below 1 mg O2/L are often referred to as hypoxic and when O2 is totally absent anoxic (often called anaerobic which technically means without air). Secondary and advanced wastewater treatment systems are generally designed to degrade organic matter to ensure adequate dissolved oxygen in waste-receiving waters (from North American Lake Management Society.
|Dissolved Oxygen Profile|
A graph of the amount of dissolved oxygen per unit depth; where the depth is on the z (vertical) axis and dissolved oxygen is on the x (horizontial) axis. Limnologists plot graphs this way but be sure to note that the depth (z) axis is really for the independent variable and the horizontal (x) axis is really for the dependent variable.
|Dissolved oxygen, DO||(EM 1110-2-5026) Oxygen molecules dissolved into bodies of water that are necessary for the respiration of most aquatic organisms. High concentrations of DO are usually present in free-flowing, tumbling water, but can be provided artificially in fish farms by special aerator pumps.||Coastal Engineering|
|Dissolved Solids Concentration|
The total mass of dissolved mineral constituents or chemical compounds in water; they form the residue that remains after evaporation and drying. Often referred to as the total dissolved salts (TDS) concentration or dissolved ion concentration. In seawater or brackish water this is approximated by the salinity of the water. All of these parameters are estimated by the electrical conductivity (EC).
|Dissolved solids||The mass of dissolved constituents in water determined by evaporating a sample to dryness, heating to 103-105 C for two hours, desiccating, and weighing.||Coastal Engineering|
|Distorted Model||Hydraulic model in which horizontal and vertical scales are different.||Coastal Engineering|
|Distortion||Conscious departure from a scaling law often necessitated by a complex set of prototype and laboratory conditions. The term is most commonly used for geometric distortion in which the vertical and horizontal scales of a hydraulic model are different.|
|Distributaries||Multiple branches of a river.||Coastal Engineering|
|Distribution curve||See grain size distribution.||Coastal Engineering|
|Distribution of time, hopper dredging||pumping:|
for dredging and hauling, the actual time the dredge pumps were operated in connection with obtaining hopper loads hauled. Where the dredge is employed exclusively in dredging and hauling economic loads, this is the total pumping time. Where the dredge is employed in agitation dredging while concurrently loading and hauling, the pumping time attributable to obtaining the hopper load is the economic pumping time multiplied by the ratio of the actual load hauled to the economic load.
for agitating, it is the actual time the dredge pumps were operated less that portion attributable to loading and hauling.
for dredging and hauling, the actual time the drags were not on the bottom because of having to turn or "back and fill" the dredge during the loading process. Where the dredge is employed exclusively for dredging and hauling economic loads, this is the total turning time. Where the dredge is employed in agitation dredging while concurrently loading and hauling, the turning time attributable to obtaining the hopper load hauled is the economic turning time multiplied by the ratio of the actual load hauled to the economic load.
for agitating, the actual time the dredge pumps were not pumping material because of having to turn or "back and fill", or otherwise maneuver the dredge less that portion attributable to loading and hauling.
travel to dump, the actual time that is spent in running from the point at which loading was terminated to the point at which dumping is commenced at the disposal site.
dumping, the actual time that is spent in dumping hopper loads in the disposal area.
returning to cut, the actual time that is spent in running from the disposal site (upon completion of dumping operations) to the point at which loading is started.
noneffective working time, n-this time is broken down as follows:
taking on fuel and supplies
traveling to and from wharf
loss due to natural elements (i.e. weather, sea, fog, etc.)
loss due to traffic and bridges
minor operating repairs (for periods not exceeding 8 hours)
transferring between works (between projects or jobs)
lay time (at dock for supplies or idle time due to work schedules)
fire and boat drills
miscellaneous (not otherwise reported)
lost time, n-this time is broken down as follows:
major repairs and alterations (for periods exceeding 8 hours)
cessation (idle time due to lack of work, lack of funds, winter layup, etc.)
collisions (repair time exceeding 8 hours will be reported under Major Repairs And Alterations.)
|Ditch||A channel to convey water for irrigation or drainage.||Coastal Engineering|
|Diurnal current||The type of tidal current having only one FLOOD and one EBB period in the tidal day. A ROTARY CURRENT is diurnal if it changes its direction through all points of the compass once each tidal day.||Coastal Engineering|
|Diurnal inequality||1. The difference in height of the two high waters or of the two low waters of each day. Also, the difference in velocity between the two daily flood or EBB CURRENTS of each day.|
2. The difference in speed between the two flood tidal currents or the two ebb currents of each tidal day. The difference changes with the declination of the
|Diurnal range||See great diurnal range.||Coastal Engineering|
|Diurnal tide level||A tidal datum midway between mean higher high water and mean lower low water.||Coastal Engineering|
|Diurnal tide||A tide with one high water and one low water in a tidal day.||Coastal Engineering|
1. Having a period or cycle of approximately 1 tidal day. Thus, the tide is said to be diurnal when only one high water and one low water occur during a tidal day, and the tidal current is said to be diurnal when there is a single flood and a single ebb period in the tidal day. A rotary current is diurnal if it changes its direction through all points of the compass once each tidal day. A diurnal constituent is one which has a single period in the constituent day. The symbol for such a constituent is usually distinguished by the subscript 1.
(See also stationary wave theory; type of tide.)
2. Having a period or cycle of approximately one TIDAL DAY.
|Diverge||The inability of the numerical model to achieve convergence by the iteration technique.||Coastal Engineering|
1. In refraction phenomena, the increasing of distance between orthogonals in the direction of wave travel. Denotes an area of decreasing wave height and energy concentration.
2. In wind-setup phenomena, the decrease in setup observed under that which would occur in an equivalent rectangular basin of uniform depth, caused by changes in planform or depth. Also the increase in basin width or depth causing such decrease in setup.
|Diverging wave||Waves that move obliquely out from a vessel's sailing line.||Coastal Engineering|
|Diversion channel or tunnel||A structure to temporarily divert water around a damsite during construction.||Coastal Engineering|
|Diversion channel||A waterway used to divert water from its natural course. The term is generally applied to a temporary arrangement e.g. to by-pass water around a dam site during construction.||Coastal Engineering|
|Diversion channels||(EM 1110-2-5026) The practice of building ditches or channels to divert rainwater and snow melt on erodible slopes and soils.||Coastal Engineering|
|Diversion||The act of, or structure built for, partially obstructing the flow of water in a channel in order to direct or alter the course of the water.||Coastal Engineering|
|Dock||The slip or waterway between two piers, or cut into the land, for the reception of ships.||Coastal Engineering|
|A small section of plotting medium (paper or mylar) added to a hydrographic smooth sheet or field sheet when it is necessary to manually plot survey data using a control point which falls beyond the limits of the sheet.||Coastal Engineering|
|Dolphin beacon||A minor light structure consisting of a number of piles driven into the bottom in a geometric or random pattern and drawn together, with a light mounted at the top.||Coastal Engineering|
1. A large post or group of piles (generally attached together) used for mooring or warping a vessel. The dolphin may be in the water, on a wharf or on the beach. A dolphin normally is more massive and is considered to be somewhat more sturdy and long-lived than a pile.
2. A cluster of piles.
|Domain||The extent of the numerical study area.||Coastal Engineering|
A particular magnitude of flow which is sometimes referred to as the "channel forming" discharge. Empirical relations have been developed between "equilibrium" stream width, depth, and slope and the dominant discharge.It has been variously defined as the bank full flow, mean annual discharge, etc.
1. An ebb tidal current where, after flood begins, the speed increases to a maximum called first ebb; it then decreases, reaching a minimum ebb near the middle of the ebb period (and at some places it may actually run in a flood direction for a short period); it then again floods to a maximum speed called second flood after which it decreases to slack water.
2. An ebb tidal current having two maxima of speed separated by a smaller ebb speed.
|Double flood||A flood tidal current having two maxima of speed separated by a smaller flood speed.||Coastal Engineering|
|Double tide||A double-headed tide, that is, a high water consisting of two maxima of nearly the same height separated by a relatively small depression, or a low water consisting of two minima separated by a relatively small elevation. Sometimes called an agger.||Coastal Engineering|
|Downdrift||The direction of predominant movement of littoral materials.||Coastal Engineering|
Along coasts with obliquely approaching waves there is a longshore (wave-driven) current. For this current, one can define an upstream and a DOWNSTREAM direction. For example, on a beach with an orientation west-east, the sea is to the north. Suppose the waves come from NW, then the current flows from West to East. Here, UPSTREAM is west of the observer, and east is downstream of the observer.
|Downwelling||A downward movement (sinking) of surface water caused by onshore Ekman transport, converging CURRENTS, or when a water mass becomes more dense than the surrounding water.||Coastal Engineering|
|Draft gauge||A device utilized to measure a vessel's draft.||Coastal Engineering|
|Draft||The depth to which a vessel is immersed when bearing a given load.||Coastal Engineering|
|Drag arm||The entire suction line aboard a hopper dredge from its attachment to the hull to its lower end, to which a draghead is attached.||Coastal Engineering|
|drag head||A device placed at the lower end of the drag arm which comes in contact with the bottom in order to dislodge material and direct it into the drag arm suction pipe. a. Ambrose -a general purpose drag which is best used in mud, silt, soft clay, light grav||Coastal Engineering|
|Drag tender||Hopper dredge employee responsible for raising and lowering the drag (pump suction head) and controlling the speed of the pump so as to keep the vacuum within the dredging range as continuously as possible.||Coastal Engineering|
|Draghead grating||Grates (a framework of parallel or crossed bars) placed across the bottom of a draghead to prevent debris and obstructions from passing through the suction and becoming lodged in the pump.||Coastal Engineering|
|Dragline trenching||(EM 1110-2-5026) As in dredging, n- as in dredging, active dredged material dewatering technique by constructing trenches inside disposal sites with dragline equipment.||Coastal Engineering|
|Drainage area||The total surface area that drains to a point of interest, typically reported in acres (small watersheds) or square miles.||Coastal Engineering|
|Drainage Basin||The area tributary to or draining into a lake, stream, or measuring site. (See WATERSHED.)||Coastal Engineering|
|Drainage lakes||Lakes having a defined surface inlet and outlet.||Coastal Engineering|
|Drawdown||A lowering of the water table of an unconfined aquifer, or of the potentiometric surface of a confined aquifer. Drawdown is the result of pumping of groundwater from wells.||Coastal Engineering|
|Dredge cut||Specific area designated for dredging, normally identified on project maps or contract plans. Buoys, targets or electronic horizontal positioning equipment are used to locate the dredge in the cut.||Coastal Engineering|
|Dredge efficiency||(Huston. Hydraulic Dredging. Theoretical...) Moving a unit of material at the lowest over-all cost.|
2. (Turner. Fundamentals...) ratio of the percent solids that the dredge averages over a period of time to the maximum percent solids achievable on an instantaneous basis.
|Dredge induced turbidity||See turbidity.||Coastal Engineering|
|Dredge ladder||Inclinable structural frame that supports the suction line, cutter system, and when used, the submerged pump on a hydraulic pipeline dredge.||Coastal Engineering|
|Dredge master||See master.||Coastal Engineering|
|Dredge plant||See attendant plant.||Coastal Engineering|
|Dredge pump||An apparatus or machine for moving or altering the pressure of fluids in confined spaces, which is used aboard a dredge for drawing a mixture of water and solid material in through the suction pipe and discharging it.||Coastal Engineering|
|Dredge runner||The impeller or rotor in a centrifugal pump which imparts motion to the dredged material. Also, it can mean the operator of the machinery on a dredge.||Coastal Engineering|
|Dredge tender||A tug that is responsible for moving non-self-propelled dredges from one dredging site to another. The tender provides other services such as placing anchors and assisting in deployment of floating discharge lines.||Coastal Engineering|
|Dredge||Any of various powerful machines for removing earth from the bed of a body of water by means of a scoop, a suction pipe, or the like.||Coastal Engineering|
|Dredgeability||The ability to excavate underwater sediments, remove them to the surface, and transport and deposit them, with respect to known or assumed equipment, methods, and in situ material characteristics.||Coastal Engineering|
|Dredged channel||An artificially maintained sea lane extending from an inland water body into the marginal sea to accomodate vessel traffic through coastal shallows.||Coastal Engineering|
|Dredged material island|
(EM 1110-2-5026) An artificial island constructed with dredged material. Dredged material islands are constructed to provide upland habitat, nesting, and resting areas for water birds, shallow water and bankline habitat for fisheries, reduce wind and wave action, oil drilling platforms, and, in Hong Kong, an airport. They may also be constructed incidental to dredging to provide a dredged material placement area.
|Dredged material placement site||Designated area for dredged material placement. In the United States, designated areas must be coordinated with the Environmental Protection Agency and resource agencies such as the U. S. Fish and Wildlife Service and the National marine Fisheries Service for environmental compliance and with local interests for capacity and acceptability.||Coastal Engineering|
|Dredged material, contaminated||See contaminated sediment.||Coastal Engineering|
|Dredged material||Material consisting of sediment or rock, excavated or dredged from waters of the United States and ocean waters and displaced or removed to a disposal location.||Coastal Engineering|
Any addition of dredged material into ocean waters. The term includes open-water dredged-material placement; return water resulting from unconfined dredged material placement operations; discharges from confined dredged-material placement facilities that enter ocean waters (such as effluent, surface runoff, or leachate); and overflow from dredge hoppers, scows, or other dredged material transport vessels.
|Dredging contract||Dredging contracts are either unit price or lump sum. a. unit price construction contract, (ER 1130-2-307) A method of procuring dredging services where payment for work completed is based on an applicable unit price from a specified section. Unit p||Coastal Engineering|
|Dredging cycle||Length of time required by a hopper dredge to fill the hopper bins to specified capacity, transport the material to a disposal site and return to the point of dredging activity.||Coastal Engineering|
|Dredging efficiency||See dredge efficiency.||Coastal Engineering|
|Dredging frequency||Time interval between required project maintenance dredging requirements. Ranges from one or more times per year to intervals of 10 to 15 years.||Coastal Engineering|
|Dredging light||A device which projects a beam of light along a set alignment. The light is white when viewed along the alignment and either red or green when viewed from slightly off alignment.||Coastal Engineering|
|Dredging mixture||See slurry.||Coastal Engineering|
|Dredging permit||A document issued by an Agency (Federal, State, etc.) that allows completion of dredging/transportation/disposal project.||Coastal Engineering|
|Dredging process||The act of excavating underwater sediments, removing them to the surface, transporting them, and subsequently depositing them in designated locations.||Coastal Engineering|
A. Effective, generally it is the time during the dredging operation when actual production is taking place. However, in rental contracts where compensation is by the hour, there may be provisions for 100 percent pay when there is no production, such as short delays for passage of vessels, etc.
B. Noneffective, n-generally the time during the dredging operation when the dredge is operational but no production is taking place, such as making changes to pipelines, cleaning trash from the head, moving between locations, etc.
C. Lost, n-time when the dredge is not operational due to malfunction of equipment and machinery, lack of required crew, or for other reasons.
(EM 1110-2-5026) That period of time when it is environmentally safe to dredge and deposit dredged material in an area occupied by species of concern, such as in the non-breeding season in areas with important waterbird colonies or non-spawning season for locally important fish species. (Include operational, environmental, weather)
|Dredging||The practice of excavating or displacing the bottom or shoreline of a water body. Dredging can be accomplished with mechanical or hydraulic machines. Most is done to maintain channel depths or berths for navigational purposes; other dredging is for shellfish harvesting, for cleanup of polluted sediments, and for placement of sand on beaches.||Coastal Engineering|
|Drift (of current)||The speed of the current.||Coastal Engineering|
|Drift current||A broad, shallow, slow-moving ocean or lake current.||Coastal Engineering|
|Drift line||A line of drifted material washed ashore and left stranded. It marks the highest stage of water, such as that associated with a storm producing coastal flooding.||Coastal Engineering|
|Drift sector||A particular reach of marine shore in which LITTORAL DRIFT may occur without significant interruption, and which contain any and all natural sources of such drift, and also any accretion shore forms accreted by such drift.||Coastal Engineering|
|Drift||1. Sometimes used as a short form for LITTORAL DRIFT.|
2. The speed at which a current runs.
3. Floating material deposited on a beach (driftwood).
4. A deposit of a continental ice sheet; e.g., a DRUMLIN.
|Drill bit||(ASTM D 653) Any device that may be attached to or is an integral part of a drill string and is used as a cutting tool to bore into or penetrate rock or other materials.||Coastal Engineering|
|Drill||(ASTM D 653) A machine or piece of equipment designed to penetrate earth or rock formations, or both.||Coastal Engineering|
|Drillability||(ASTM D 653) Index value of the resistance of a rock to drilling.||Coastal Engineering|
|Drilling parameter recorder, dpr|
A generic name for systems used to record the operational parameters of a drill rig. The nature of subsurface rock materials can be inferred from the various drilling parameters such as bit force, speed of rotation, instantaneous advance rate, etc. A DPR has been proven and applications further developed for dredging exploration as part of the Corps Dredging Research Program (DRP). See Dredging Research, Vol. DRP-91-2.
|Drilling, rotary||See rotary drilling.||Coastal Engineering|
|Dromond||A large medieval fast-sailing galley or cutter.||Coastal Engineering|
|Drop (inlet) structure||A stop log (or flashboard) weir device used for ponding water and controlling the return of effluent water from a confined disposal facility.||Coastal Engineering|
|Drop structure||A grade control structure that provides for a vertical drop in the channel invert between the upstream and downstream sides.||Coastal Engineering|
|Drowned coast||A shore with long, narrow channels, implying that subsidence of the coast has transformed the lower portions of river valleys into tidal estuaries.||Coastal Engineering|
|Drumlin||A low, smoothly-rounded, elongate hill of compact glacial till built under the margin of the ice and shaped by its flow.||Coastal Engineering|
|Dry density||The total weight of solids per unit of volume.||Coastal Engineering|
|Dry deposition||Fine particulate matter and aerosols settling from the atmosphere onto lake and land surfaces during periods with no precipitation.||Coastal Engineering|
|Dry unit weight||See dry density||Coastal Engineering|
|Drying beach||That part of the beach which is uncovered by water (e.g. at low tide). Sometimes referred to as 'SUBAERIAL' beach.||Coastal Engineering|
Cutterhead dredge employee having responsibility for all shore-based activities. Among them are the supervision of pipe-laying crews, levee maintenance, adding of discharge pipe at disposal location, and supervision of clearing crews.
|Dump shack||See end shack.||Coastal Engineering|
|Dumpability||The ability of a soil to be dumped (removed by gravity) from a transport container without sticking to the container or forming a bridge at the discharge opening.||Coastal Engineering|
|Dumping||See ocean dumping.||Coastal Engineering|
|Dune ridge||A series of parallel dunes, whose movements are arrested by the growth of vegetation, along the shore of a retreating sea.||Coastal Engineering|
|Dune sand||A type of blown sand that has been piled up by the wind into a sand dune, usually consisting of rounded quartz grains having diameters ranging from 0.1 to 1 mm.||Coastal Engineering|
1. Underwater. Flow-transverse bedform with spacing from under 1 m to over 1,000 m that develops on a sediment bed under unidirectional currents. On land - A rounded hill or ridge of sand heaped up by action of the wind.
2. Bed forms with triangular profile that advance downstream due to net deposition of particles on the steep downstream slope. Dunes move downstream at velocities that are small relative to the streamflow velocity.
3. Ridges or mounds of loose, wind-blown material, usually sand.
4. Bed forms smaller than bars but larger than ripples that are out of phase with any water-surface gravity waves associated with them.
|Dunes||Bed forms with triangular profile that advance downstream due to net deposition of particles on the steep downstream slope. Dunes move downstream at velocities that are small relative to the streamflow velocity.||Coastal Engineering|
|Dupuit assumptions||The following assumptions for flow in an unconfined aquifer (a) hydraulic gradient is equal to the slope of the water table, (b) streamlines are horizontal, and (c) equipotential lines are vertical.||Coastal Engineering|
|Durability||The ability of a rock to retain its physical and mechanical properties (i.e. resist degradation) in engineering service.||Coastal Engineering|
|Duration minimum||The time necessary for steady-state wave conditions to develop for a given wind velocity over a given fetch length.||Coastal Engineering|
|Duration of ebb||The interval of time in which a tidal current is ebbing, determined from the middle of the slack waters.||Coastal Engineering|
|Duration of fall||The interval from high water to low water.||Coastal Engineering|
|Duration of flood and duration of ebb|
Duration of flood is the interval of time in which a tidal current is flooding, and duration of ebb is the interval in which it is ebbing, these intervals being reckoned from the middle of the intervening slack waters or minimum currents. Together they cover, on an average, a period of 12.42 hours for a semidiurnal tidal current or a period of 24.84 hours for a diurnal current. In a normal semidiurnal tidal current, the duration of flood and duration of ebb each will be approximately equal to 6. 21 hours, but the times may be modified greatly by the presence of nontidal flow. In a river the duration of ebb is usually longer than the duration of flood because of fresh water discharge, especially during spring months when snow and ice melt are predominant influences.
|Duration of flood||The interval of time in which a tidal current is flooding, determined from the middle of slack waters.||Coastal Engineering|
|Duration of rise and duration of fall|
Duration of rise is the interval from low water to high water, and duration of fall is the interval from high water to low water. Together they cover, on an average, a period of 12.42 hours for a semidiurnal tide or a period of 24.84 hours for a diurnal tide. In a normal semidiurnal tide, duration of rise and duration of fall each will be approximately equal to 6.21 hours, but in shallow waters and in rivers there is a tendency for a decrease in duration of rise and a corresponding increase in duration of fall.
|Duration of rise||The interval from low water to high water.||Coastal Engineering|
|Duration, minimum||The time necessary for steady-state wave conditions to develop for a given wind velocity over a given fetch length.||Coastal Engineering|
|Duration||In wave forecasting, the length of time the wind blows in nearly the same direction over the FETCH (generating area).||Coastal Engineering|
|During dredging survey||See interim (contract) hydrographic survey.||Coastal Engineering|
|dustpan dredge||See dredge, hydraulic, pipeline, dustpan.||Coastal Engineering|
|Dyke||See dike||Coastal Engineering|
|Dynamic decimeter||See geopotential.||Coastal Engineering|
|Dynamic depth (height) anomaly||See geopotential anomaly.||Coastal Engineering|
|Dynamic depth (height)||See geopotential difference.||Coastal Engineering|
|Dynamic equilibrium||Short term morphological changes that do not affect the morphology over a long period.||Coastal Engineering|
|Dynamic meter (d)||The former practical unit for geopotential difference (dynamic depth), equal to 10 geopotentials (dynamic decimeters). (See also geopotential anomaly.)||Coastal Engineering|
|Dynamic Model||A mathematical model of flow in an open channel that solves the complete unsteady flow equations (St. Venant equations for one-dimensional problems).||Coastal Engineering|
|Dynamic modulus of elasticity||The modulus of elasticity computed from the size, weight, shape, and fundamental frequency of vibration of a concrete test specimen, or from pulse velocity (ACI 116R-85).||Coastal Engineering|
|Dynamic position (positioning)||(EM 1110-2-1003) A position determined while a vessel is in motion (Used synonymously with kinematic positioning.)||Coastal Engineering|
|Dynamic topography||See geopotential topography.||Coastal Engineering|
In fluid dynamics, the ratio between the shear stress acting along any plane between neighboring fluid elements and the rate of deformation of the velocity gradient perpendicular to this plane.
back to top
|Eager||See BORE.||Coastal Engineering|
|Eagre (eager)||See tidal bore.||Coastal Engineering|
|Earth Tide||Periodic movement of the Earth's crust caused by gravitational interactions between the Sun, Moon, and Earth.||Coastal Engineering|
|East Greenland Current||A North Atlantic Ocean current setting southward and then southwestward along the east coast of Greenland.||Coastal Engineering|
|Ebb Axis||Average direction of current at strength of ebb.||Coastal Engineering|
|Ebb Current||The movement of a tidal current away from shore or down a tidal stream. In the semidiurnal type of reversing current, the terms greater ebb and lesser ebb are applied respectively to the ebb currents of greater and lesser velocity of each day. The terms of maximum ebb and minimum ebb are applied to the maximum and minimum velocities of a continuously running ebb current, the velocity alternately increasing and decreasing without coming to a slack or reversing. The expression maximum ebb is also applicable to any ebb current at the time of greatest velocity.||Coastal Engineering|
|Ebb Delta||A tidal delta formed seaward of an inlet by ebbing tidal currents and modified in shape by waves. Syn: ebb-tidal shoal or ebb-tidal delta.||Coastal Engineering|
|Ebb Interval||The interval between the transit of the moon over the meridian of a place and the time of the following strength of ebb.||Coastal Engineering|
|Ebb Shield||High, landward margin of a flood-tidal shoal that helps divert ebb-tide currents around the shoal.||Coastal Engineering|
|Ebb Spit||A spit formed by ebb-tidal currents.||Coastal Engineering|
|Ebb Strength (Strength of Ebb)||Phase of the ebb tidal current at the time of maximum speed. Also, the speed at this time. (See also strength of current.)||Coastal Engineering|
|Ebb Strength||The EBB CURRENT at the time of maximum velocity.||Coastal Engineering|
|Ebb Tidal Delta||The bulge of sand formed at the seaward mouth of TIDAL INLETS as a result of interaction between tidal currents and waves. Also called inlet-associated bars and estuary entrance shoals.||Coastal Engineering|
|Ebb Tide||The period of tide between high water and the succeeding low water; a falling tide.||Coastal Engineering|
|Ebb||Period when tide level is falling; often taken to mean the ebb current which occurs during this period.||Coastal Engineering|
|Eccentricity of Orbit||Ratio of the distance from center to focus of orbit to the semimajor axis. The eccentricity of orbit = 0 where A and B are respectively the semimajor and semiminor axes of the orbit.||Coastal Engineering|
|Eccentricity||(EM 1110-2-1003) An offset between measurement reference points.||Coastal Engineering|
|Echo Sounder||An electronic instrument used to determine the depth of water by measuring the time interval between the emission of a sonic or ultrasonic signal and the return of its echo from the bottom.||Coastal Engineering|
|Echogram||A graphic record of depth measurements obtained by an echo sounder. (See also echo sounder; fathogram.)||Coastal Engineering|
|Ecliptic||The intersection of the plane of the Earth's orbit with the celestial sphere.||Coastal Engineering|
|Ecological pyramid||Conceptual scheme whereby the amount of biomass or energy at each level of the food "chain" decreases as you move from primary producers through the different levels of consumers.||Coastal Engineering|
|Economic Load||That loading of a hopper dredge taking into consideration pumping times and settling rates which results in the removal of the maximum amount of material in a day's operation.||Coastal Engineering|
|Ecoregion||An environmental area characterized by specific land uses, soil types, surface form, and potential natural vegetation.||Coastal Engineering|
|Ecosystem||1. The living organisms and the nonliving environment interacting in a given area, encompassing the relationships between biological, geochemical, and geophysical systems.|
2. A community and its environment including living and nonliving components.
|Eddy Current||See EDDY.||Coastal Engineering|
|Eddy Viscosity Tensor||The eddy viscosity tensor defines the orientation (relative to the +x axis) of the primary longitudinal eddy viscosity, which is normally aligned with the primary flow direction. In other words, the Exx (x momentum turbulent exchange in the x direction) is applied to the dominant or longitudinal direction of flow. For riverine cases, this angle may be set to the local river axis. This will then allow you to relax the transverse eddy viscosities. For estuarine conditions where it is difficult to define a primary flow direction, this variable is normally ignored and the transverse and longitudinal eddy viscosities are set the same.||Coastal Engineering|
|Eddy||A circular movement of water formed on the side of a main current. Eddies may be created at points where the main stream passes projecting obstructions or where two adjacent currents flow counter to each other.||Coastal Engineering|
|Edge Wave||An ocean wave parallel to a coast, with crests normal to the shoreline. An edge wave may be STANDING or PROGRESSIVE. Its height diminishes rapidly seaward and is negligible at a distance of one wavelength offshore.||Coastal Engineering|
|Eeffective Diameter||(ASTM D 653) Particle diameter corresponding to 10 % finer on the grain-size curve.||Coastal Engineering|
|Effective Discharge||The discharge that transports the largest fraction of the annual sediment load. The effective discharge results in the average morphologic characteristics of a channel and at which channel maintenance is the most effective.||Coastal Engineering|
|Effective Grain Size||The grain size conesponding to the one that is 10 percent finer by weight line on the grain-size distribution curve.||Coastal Engineering|
|Effective Hopper Capacity||Hopper volume usable in retaining dredged material; usually less than total hopper volume.||Coastal Engineering|
|Effective Peak Ground Acceleration||That acceleration which is most closely related to structural response and to damage potential of an earthquake. It differs from, and is less than, the peak free-field ground acceleration (Newmark and Hall 1982).||Coastal Engineering|
|Effective Pumping Time||See dredging time.||Coastal Engineering|
|Effective Size||See effective diameter.||Coastal Engineering|
|Effective Stress (Effective Pressure) (Intergranular Pressure)||The normal force per unit area transmitted from grain to grain of a soil mass. It is the stress that is effective in mobilizing internal friction.||Coastal Engineering|
|Effective Time||See dredging time.||Coastal Engineering|
|Efficiency Loss||The loss in productivity of labor and equipment required to perform a given task, which may result from actions of the government under a contract clause. It is usually expressed as a percentage.||Coastal Engineering|
|Effluent Quality||(EM 1110-2-5026) The measure of quality of water coming over the weir in a confined dredged material disposal site during and after a disposal operation.||Coastal Engineering|
|Effluent||Any water flowing from a confined disposal facility during and as a result of dredged material placement. (See also confined disposal facility.)|
Synonym : Confined Disposal Facility
|Ekman Spiral||A logarithmic spiral (when projected on a horizontal plane) formed by current velocity vectors at increasing depth intervals. The current vectors become progressively smaller with depth. They spiral to the right (looking in the direction of flow) in the Northern Hemisphere and to the left in the Southern with increasing depth. Theoretically, the surface current vector sets 45? from the direction toward which the wind is blowing. Flow opposite to the surface current occurs at the so-called "depth of frictional resistance".|
The phenomenon occurs in wind drift currents in which only the Coriolis and frictional forces are significant. Named for Vagn Walfrid Ekman who, assuming a constant eddy viscosity, steady wind stress, and unlimited depth and extent, published on the effect in 1905.
|Ekman Transport||Resultant flow at right angles to and to the right of the wind direction (in the northern hemisphere) referred to as UPWELLING and DOWNWELLING.||Coastal Engineering|
|El Niño||Warm equatorial water which flows southward along the coast of Peru and Ecuador during February and March of certain years. It is caused by poleward motions of air and unusual water temperature patterns in the Pacific Ocean, which cause coastal downwelling, leading to the reversal in the normal north-flowing cold coastal currents. During many El Niño years, storms, rainfall, and other meteorological phenomena in the Western Hemisphere are measurably different than during non-El Niño years.||Coastal Engineering|
|Elastic Design||Design based on a linear stress-strain relationship and elastic properties of the materials.||Coastal Engineering|
|lastic Limit||The limit of stress without undergoing permanent deformation.||Coastal Engineering|
|Elbow Pontoon||See pontoon.||Coastal Engineering|
|Electric Tape Gage||A tide gage consisting of a Monel metal tape on a metal reel (with supporting frame), voltmeter, and battery. The tape is graduated with numbers increasing toward the unattached end. Tidal heights can be measured directly by unreeling the tape into its stilling well. When contact is made with the water's surface, the circuit is completed and the voltmeter needle moves. At that moment the length of tape is read against an index mark, the mark having a known elevation relative to the tidal bench marks. Used at many long-term control stations in place of the tide staff. ||Coastal Engineering|
|Electrical Conductivity (EC)||See Conductivity.||Coastal Engineering|
|Electromagnetic Radiation||Radiation that travels through space at the speed of light that includes light, radio waves, x-rays, and gamma rays.||Coastal Engineering|
|Electronic Distance Measurement, edm||(EM 1110-2-1003) Pulsing or phase comparison determination of a distance.||Coastal Engineering|
|Electronic Positioning System, eps||(EM 1110-2-1003) A system which receives two or more electronic distance measurements to obtain a position.||Coastal Engineering|
|Elevation||The vertical distance from mean sea level or other established datum plane to a point on the earth's surface; height above sea level. Although sea floor elevation below msl should be marked as a negative value, many charts show positive numerals for water depth.||Coastal Engineering|
|Elimination||One of the final processes in the harmonic analysis of tides in which preliminary values for the harmonic constants of a number of constituents are cleared of the residual effects of each other.||Coastal Engineering|
|Elliptical Mouth||The suction mouth opening within a cutterhead, depressed on the top and widened on the sides, to fit into the cutter below its center.||Coastal Engineering|
|Elutriation||The process by which a granular material can be sorted into its constituent particle sizes by means of a moving stream of fluid (usually air or water). Elutriators are extensively used in studies of sediments for determining Particle size distribution. Under certain circumstances wind, rivers and streams may act as elutriating agents.||Coastal Engineering|
|Embankment||Fill material, usually earth or rock, placed with sloping sides and with a length greater than its height. Usually an embankment is wider than a dike.||Coastal Engineering|
|Embayment||An indentation in the shoreline forming an open bay.||Coastal Engineering|
|Embeddedness||The degree to which the coarse channel bed materials (boulders, cobble, gravel, sand) are surrounded or covered by fine sediments, usually measured as percent coverage by finer sediments.||Coastal Engineering|
|Emergency||A "situation which would result in an unacceptable hazard to life or navigation, a significant loss of property, or an immediate and unforeseen significant economic hardship if corrective action is not taken within a time period of less than the normal time needed under standard procedures." (33 CFR Part 335.7).||Coastal Engineering|
|Emergent Coast||A coast in which land formerly under water has recently been exposed above sea level, either by uplift of the land or by a drop in sea level.||Coastal Engineering|
|Empirical Model||Representation of a real system by a mathematical description based on experimental or observed data rather than on general physical laws.||Coastal Engineering|
|End Shack||Small barge mounted building located at the end of a floating pipeline.||Coastal Engineering|
|Endangered Species||(EM 1110-2-5026) Plant or animal species of such limited and declining populations that they have been legally placed on a Federal or state Endangered Species List. Federally-listed species and their needs are published in the Federal Register. Species that decline to the endangered status usually do so as a result of degradation or destruction of habitat.||Coastal Engineering|
|Endemic||Native or confined to a specific geographic area.||Coastal Engineering|
|Endothermic Reaction||A reaction which absorbs heat.||Coastal Engineering|
|Energy Coefficient||The ratio of the energy in a wave per unit crest length transmitted forward with the wave at a point in shallow water to the energy in a wave per unit crest length transmitted forward with the wave in deep water. On refraction diagrams this is equal to the ratio of the distance between a pair of orthogonals at a selected shallow-water point to the distance between the same pair of orthogonals in deep water. Also the square of the REFRACTION COEFFICIENT.||Coastal Engineering|
|Energy Dissipater||A device used to reduce water pressure or velocity to a safe level.||Coastal Engineering|
|Engineering Change||A change in design requiring revised drawings and/or specifications.||Coastal Engineering|
|Entrainment, as in Dredging||Sediment in suspension and flowing with the carrier water.||Coastal Engineering|
|Entrance||The avenue of access or opening to a navigable channel or inlet.||Coastal Engineering|
|Entrenched Channel||A channel that has eroded downward or was constructed such that it no longer has access to its original floodplain during moderate flow events.||Coastal Engineering|
|Entrenchment Ratio||The ratio between the flood-prone width and the bankfull width.||Coastal Engineering|
|Entrenchment||A vertical description of the stream. Flood flows in an entrenched stream are contained within the streambanks or adjacent terraces. Flood flows in a stream that is not entrenched are spread out over a floodplain. For the purpose of this glossary, entrenchment and incision are synonymous.||Coastal Engineering|
|Environment||Surroundings, the physical and biological system supporting life, including human and their built environment.||Coastal Engineering|
|Eolian (Also Aeolian)||Pertaining to the wind, esp. used with deposits such as loess and dune sand, and sedimentary structures like wind-formed ripple marks.||Coastal Engineering|
|Eolian Sands||Sediments of sand size or smaller which have been transported by winds. They may be recognized in marine deposits off desert coasts by the greater angularity of the grains compared with waterborne particles.||Coastal Engineering|
|Ephemeral Stream||A stream that flows only during runoff events.||Coastal Engineering|
|Ephemeris||The predictions of current satellite position that are transmitted to the user in the data message.||Coastal Engineering|
The upper, wind-mixed layer of a thermally stratified lake. This water is turbulently mixed throughout at least some portion of the day and because of its exposure, can freely exchange dissolved gases (such as O2 and CO2) with the atmosphere.
|Epoch||Also known as phase lag. Angular retardation of the maximum of a constituent of the observed tide (or tidal current) behind the corresponding maximum of the same constituent of the theoretical equilibrium tide. It may also be defined as the phase direction.||Coastal Engineering|
|Equal Transit Rate||Obsolete, replaced by the term "equal-width increment."||Coastal Engineering|
|Equal-discharge -increment (edi) Method||A procedure for obtaining the discharge-weighted suspended-sediment concentration at a cross section by (1) collecting a depth-integrated sample at the center of equal-flow sub-sections across the cross section while (2) using vertical transit rates that provide the same volume of sample at each sampling vertical.||Coastal Engineering|
|Equal-width Increment |
|A procedure for obtaining the dischargeweighted suspended- sediment concentration of flow at a cross section by - (1) performing depth integration at a series of verticals equally spaced across the cross section, and by (2) using the same vertical transit rate at all sampling verticals.||Coastal Engineering|
|Equation of Time||Difference between mean and apparent time. From the beginning of the year until near the middle of April, mean time is ahead of apparent time, the difference reaching a maximum of about 15 minutes near the middle of February. From the middle of April to the middle of June, mean time is behind apparent time but the difference is less than 5 minutes. From the middle of June to the first part of September, mean time is again ahead of apparent time with a maximum difference less than 7 minutes.|
From the first of September until the later part of December, mean time is again behind apparent time, the difference reaching a maximum of nearly 17 minutes in the early part of November. The equation of time for each day in the year is given in the American Ephemeris and Nautical Almanac.
|Equatorial Countercurrent||A current setting eastward between the North and South Equatorial Currents of the Atlantic, Pacific, and Indian (in northern winter) Oceans. In the Atlantic and Pacific, its axis lies about latitude 7" north and in the Indian, about 7" south.||Coastal Engineering|
|Equatorial Currents||1. Ocean currents flowing westerly near the equator. There are two such currents in both the Atlantic and Pacific Oceans. The one to the north of the equator is called the North Equatorial Current and the one to the south is called the South Equatorial Current. Between these two currents there is an easterly flowing stream known as the Equatorial Countercurrent.|
2. Tidal currents occurring semimonthly as a result of the moon being over the equator. At these times the tendency of the moon to produce DIURNAL INEQUALITY in the current is at a minimum.
|Equatorial Tidal Currents||Tidal currents occurring semimonthly as a result of the Moon being over the equator. At these times the tendency of the Moon to produce a diurnal inequality in the tidal current is at a minimum.||Coastal Engineering|
|Equatorial Tides||Tides occurring semimonthly as the result of the moon being over the equator. At these times the tendency of the moon to produce a DIURNAL INEQUALITY in the tide is at a minimum.||Coastal Engineering|
Asubsurface current setting eastward along the equator in the Pacific, Atlantic, and Indian Oceans. In the Pacific, its core of maximum velocity lies at a depth of about 100 meters within the South Equatorial Current.
|Equilibrium Argument||The theoretical phase of the equilibrium tide. It is usually represented by the expression (V + u), in which V is a uniformly changing angular quantity involving multiples of the hour angle of the mean Sun, the mean longitudes of the Moon and Sun, and the mean longitude of lunar or solar perigee; and u is a slowly changing angle depending upon the longitude of the Moon's node. When pertaining to an initial instant of time, such as the beginning of a series of observations, it is expressed by (V0 + u).||Coastal Engineering|
|Equilibrium Theory||A model under which it is assumed that the waters covering the face of the Earth instantly respond to the tide-producing forces of the Moon and Sun to form a surface of equilibrium under the action of these forces. The model disregards friction, inertia, and the irregular distribution of the land masses of the Earth/ The theoretical tide formed under these conditions is known as the equilibrium tide.||Coastal Engineering|
|Equilibrium Tide||Hypothetical tide due to the tide-producing forces under the equilibrium theory. Also known as gravitational tide.||Coastal Engineering|
|Equilibrium||A condition of fluvial systems in which watershed and channel parameters are balanced.||Coastal Engineering|
|Equinoctial Tides||Tides occurring near the times of the equinoxes.||Coastal Engineering|
|Equinoctial||The celestial equator.||Coastal Engineering|
|Equinoxes||The two points in the celestial sphere where the celestial equator intersects the ecliptic; also, the times when the Sun crosses the equator at these points. The vernal equinox is the point where the Sun crosses the equator from south to north and it occurs about March 21. Celestial longitude is reckoned eastward from the vernal equinox. The autumnal equinox is the point where the Sun crosses the equator from north to south and it occurs about September 23.||Coastal Engineering|
|Equipment Accessibility||(EM 1110-2-5026) On disposal sites, this term refers to the ability of heavy equipment to economically and efficiently travel to and work in disposal sites and handle dredged material.||Coastal Engineering|
|Equipment||Items not included in plant.||Coastal Engineering|
|Equipotential Line||A line in a two-dimensional groundwater flow field such that the total hydraulic head is the same for all points along the line.||Coastal Engineering|
|Equipotential Surface||A surface in a three-dimensional groundwater flow field such that the total hydraulic head is the same everywhere on the surface.||Coastal Engineering|
|A contract adjustment in price or time, or both, to compensate the contractor for expense or delay incurred due to actions of the government or to compensate the government for contract reductions.||Coastal Engineering|
|Erodability||The relative amount of energy required to excavate particles, or aggregations of particles, by erosion, or scouring, with a moving fluid.||Coastal Engineering|
|Erodible Slopes||(EM 1110-2-5026) Slopes of more than three feet per 100 feet that, when bare of vegetative cover, are highly erosive, especially those primarily made of silt and silty clay soils.||Coastal Engineering|
|Erosion||The wearing away of land by the action of natural forces. On a beach, the carrying away of beach material by wave action, tidal cur-rents, littoral currents, or by deflation.||Coastal Engineering|
|Error||In quality assurance, the numerical difference between the measured value of a quality characteristic and its mean, true, or reference value.||Coastal Engineering|
|Escarpment||A more or less continuous line of cliffs or steep slopes facing in one general direction which are caused by erosion or faulting. Also SCARP.||Coastal Engineering|
of the Port
|Also known as high water full and change (HWF&C). Average high water interval on days of the new and full Moon. This interval is also sometimes called the common or vulgar establishment, to distinguish it from the corrected establishment, the latter being the mean of all the high water intervals. The latter is usually 10 to 15 minutes less than the common establishment.||Coastal Engineering|
|Estimated Quantity||The quantity indicated in the bid schedule estimated to be that required to complete a bid item.||Coastal Engineering|
|Estuarine||1. (NAVFAC DM-26.3) Formed in an estuary.|
2. Found in estuaries.
|Estuary||1. The part of a river that is affected by tides.|
2. The region near a river mouth in which the fresh water of the river mixes with the salt water of the sea.
|Eularian measurement||Observation of a current with a device fixed relative to the flow.||Coastal Engineering|
|Euphotic zone||Layer of water where sunlight is sufficient for photosynthesis to occur.|
|Euryhaline||Tolerates different salinity levels.||Coastal Engineering|
|Eustatic Sea Level Change||Change in the relative volume of the world's ocean basins and the total amount of ocean water.||Coastal Engineering|
|Eustatic sea level rate||The world wide change of sea level elevation with time. The changes are due to such causes as glacial melting or formation, thermal expansion or contraction of sea water, etc.||Coastal Engineering|
|Eutrophic Lake||A very biologically productive type of lake due to relatively high rates of nutrient input. See Eutrophication.||Coastal Engineering|
|Eutrophication||The process by which lakes and streams are enriched by nutrients (usually phosphorus and nitrogen) which leads to excessive plant growth - algae in the open water, periphyton (attached algae) along the shoreline, and macrophytes (the higher plants we often call weeds) in the nearshore zone. See the Lake Ecology Primer Biology section for more information about this problem; it remains the biggest pollution problem for Minnesota‘s (and in fact for the rest of our country as well) lakes . The extent to which this process has occurred is reflected in a lake's trophic classification: oligotrophic (nutrient poor), mesotrophic (moderately productive), and eutrophic (very productive and fertile).|
The less productive a lake is naturally, the more sensitive it is to increased nutrient loads from human-caused disturbances in the watershed.
|Evaporation||The process of converting liquid to vapor.||Coastal Engineering|
|Evapotranspiration||The sum of evaporation and transpiration.||Coastal Engineering|
|Evection||A perturbation of the Moon depending on the alternate increase of the eccentricity of its orbit, which is always a maximum when the Sun is passing the Moon's line of apsides and a minimum when the Sun is at right angles to it. The principal constituents in the tide resulting from the evectional inequality are v2,?2, and ?1.||Coastal Engineering|
|Event marker||A device that is activated in an electronic positioning system to obtain coordinates at the point of activation.||Coastal Engineering|
|Examination hydrosurvey||See before dredging survey.||Coastal Engineering|
|Excel||Refers to Microsoft’s Excel spreadsheet software.||Coastal Engineering|
|Excusable delay||A delay in the work for which, under the terms of the contract, a time extension can be granted.||Coastal Engineering|
|Exfoliation||A type of jointing which occurs in concentric shells around a rock mass - caused by the release of confining pressure.||Coastal Engineering|
|Exothermic Reaction||A reaction which gives off heat; see also endothermic reaction.||Coastal Engineering|
|Expansion joint||A joint between parts of a concrete structure to allow for thermal changes to occur independently.||Coastal Engineering|
|Expedite||In contracting, the advancement of the interim or final completion date established in a construction contract.|
|Expedited procedure||In change orders, (USACE. Huntsville Div. Construction...) issuing a Notice to Proceed before completion of negotiations of a change order.||Coastal Engineering|
|Explicit Scheme||Scheme in which the governing equations of a numerical model are arranged to update the dependent variables in terms of previously known values only. (Compare with IMPLICIT SCHEME).||Coastal Engineering|
|Export rates||Amount of a particular nutrient or contaminant annually transported from its source to a lake or stream; usually related to land uses and expressed per unit area per year.||Coastal Engineering|
|Extensibility||The maximum tensile strain of concrete before cracking.||Coastal Engineering|
|Extrapolation||Estimation of a function at a point which is larger or smaller than all the points at which the value of the function is known.||Coastal Engineering|
|Extreme high water||The highest elevation reached by the sea as recorded by a tide gage during a given period. The National Ocean Service routinely documents monthly and yearly extreme high waters for its control stations.||Coastal Engineering|
|Extreme low water||The lowest elevation reached by the sea as recorded by a tide gage during a given period. The National Ocean Service routinely documents monthly and yearly extreme low water for its control stations.||Coastal Engineering|
|Eye||In meteorology, usually the "eye of the storm" (hurricane)): the roughly circular area of comparatively light winds and fair weather found at the center of a severe tropical cyclone.||Coastal Engineering|
back to top
|Fabridam||A dam constructed of fabric and rubber that can be inflated with air or water.||Coastal Engineering|
|Face angle (cutter)||One-half the cone angle. (See also cone angle.)||Coastal Engineering|
|Face||Vertical thickness of the layer of material that is being dredged. Stated in feet it is normally given as an average across the width of the dredge cut.||Coastal Engineering|
|Fairway||The parts of a waterway that are open and unobstructed for navigation. The main traveled part of a waterway; a marine thoroughfare.||Coastal Engineering|
|Fall velocity||The falling or settling rate of a particle in a given medium.||Coastal Engineering|
|Far-infragravity||The frequency band (nominally 0.001 - 0.02 Hz) occupied by SHEAR INSTABILITIES of the longshore current. This band falls both below and in the lower part of the Infragravity band occupied by Infragravity waves.||Coastal Engineering|
|Fast-switching frequency||A single channel which rapidly samples a number of satellite ranges. "Fast" means that the switching time is sufficiently fast (2 to 5 milliseconds) to recover the data message.||Coastal Engineering|
A graphic record of depth measurements obtained by a fathometer. The term is frequently improperly used to refer to an echogram. (See also echogram.)
Synonym : Echogram
|Fathom||A unit of measurement used for soundings equal to 1.83 meters (6 feet).||Coastal Engineering|
|Fathometer||The copyrighted trademark for a type of ECHO SOUNDER. (see depth finder)||Coastal Engineering|
|Fault||A fracture in rock along which there has been an observable amount of displacement. Faults are rarely single planar units; normally they occur as parallel to sub-parallel sets of planes along which movement has taken place to a greater or lesser extent. Such sets are called fault or fracture-zones.||Coastal Engineering|
|Fauna||The entire group of animals found in an area.||Coastal Engineering|
|Feasibility study survey||(EM 1110-2-1003) Survey performed in support of feasibility studies in advance of detailed engineering design.||Coastal Engineering|
|Federal project||Any work or activity of any nature and for any purpose that is to be performed by or for the Secretary of the Army acting through the Chief of Engineers pursuant to Congressional authorizations. It does not include work requested by any other Federal agency on a cost reimbursable basis.||Coastal Engineering|
|Federal standard||(404 Manual) The dredged material disposal alternative(s) identified by the U.S. Army Corps of Engineers that represent the least costly alternative(s) consistent with sound engineering practices and which meet the environmental standards established by the 404(b)(1) evaluation process. See Engler et.al. (1988).||Coastal Engineering|
|Feeder beach||An artificially widened beach serving to nourish downdrift beaches by natural littoral currents or forces.||Coastal Engineering|
|Feeder berm||(DRP 5-02) Nearshore berm constructed of clean dredged sand placed in relatively shallow coastal water to enhance adjacent beaches and nearshore areas by mitigating erosive wave action and by providing an addition source of sand to the littoral system. (See berm)||Coastal Engineering|
|Feeder current||The currents which flow parallel to shore before converging and forming the neck of a RIP CURRENT. (See current, feeder)||Coastal Engineering|
|Feeling bottom||The initial action of a deepwater wave, in response to the bottom, upon running into shoal water.||Coastal Engineering|
|Fetch length||The horizontal distance (in the direction of the wind) over which a wind generates seas or creates a WIND SETUP.||Coastal Engineering|
|Fetch||The area in which SEAS are generated by a wind having a fairly constant direction and speed. Sometimes used synonymously with FETCH LENGTH. Also GENERATING AREA.||Coastal Engineering|
|Fetch-limited||Situation in which wave energy (or wave height) is limited by the size of the wave generation area (fetch).||Coastal Engineering|
|Field capacity||The maximum amount of water that the unsaturated zone of a soil can hold against the downward pull of gravity.||Coastal Engineering|
|Field change||Field change is one initiated by the area or resident engineer to make minor revisions to the contract plans and specifications to adjust to actual field conditions encountered.||Coastal Engineering|
|Field data||Actual data collected at the study site. Field data can consists of water depths, flow velocities, flow directions, samples of sediment concentrations, bottom grab samples, bathymetric surveys, etc.||Coastal Engineering|
|Field edit||As defined in this text, is the process of on site examinations and measurements designed to ensure that detail and nomenclature, as portrayed or descried on previously compiled documents, is current, reliable, and adequate for its intended purpose.||Coastal Engineering|
|Field examination||A special purpose NOS hydrographic, wire drag, or side scan sonar survey of very limited area; i.e., usually an investigation of one or more individual and scattered items.||Coastal Engineering|
|Field sheet||The worksheet that graphically displays the hydrographer's representation of all surface and subsurface features in the area being surveyed. See Section 1.2.1 of the Hydrographic Manual.||Coastal Engineering|
|Fill material||(EM 1110-2-5026) As in the Clean Water Act (CA), any material used to replace an aquatic area with upland area, or for changing the bottom elevation of a waterbody. As in dredging, dewatered dredged material used beneficially as foundation material in upland areas for any structure from roads to buildings to landfill. (See also artificial accretion.)||Coastal Engineering|
|Fill||Man-made deposits of natural soils and rock products; may include organic matter and waste materials.||Coastal Engineering|
|Fillet (coastal engineering)||1. (NAVFAC DM-26.3) The accumulation of a littoral material adjacent to a coastal structure such as a groin or a jetty.|
2. The widening of a channel bend.
|Fillet||The accumulation of a littoral material adjacent to a coastal structure such as a groin or a jetty.||Coastal Engineering|
|Filter||Intermediate layer, preventing fine materials of an underlayer from being washed through the voids of an upper layer.||Coastal Engineering|
|Filtrate||The fluid that has passed through a filter.||Coastal Engineering|
|Filtration||The process of passing a liquid through a filter to remove suspended matter that usually cannot be removed by settling. The filter may consist of granular material such as sand, magnetite, or diatomaceous earth; finely woven cloth, unglazed porcelain, or specially prepared paper.||Coastal Engineering|
|Final contract payment||The last payment made by the government to a contractor for all work performed under the contract, after which no new claims may be made by the contractor. This is accomplished by marking the last payment with the word "final."||Coastal Engineering|
|Fine clay||A geologic term for a clay particle having a diameter in the range of 1/2048 to 1/1024 mm (0.5-1 micron, or 11 to 10 phi units). Also, a loose aggregate of clay consisting of fine clay particles.||Coastal Engineering|
|Fine material||Particles of a size finer than the particles present in appreciable quantities in the bed material; normally silt and clay particles (particles finer than 0.062 mm).||Coastal Engineering|
|Fine sand||1. A geologic term for a sand particle having a diameter in the range of 0.125-0.25 mm (125-250 microns, or 3 to 2 phi units). Also, a loose aggregate of sand consisting of fine sand particles.||Coastal Engineering|
|Fine silt||A geologic term for a silt particle having a diameter in the range of 1/128 to 1/64 mm (8-16 microns, or 7 to 6 phi units). Also, a loose aggregate of silt consisting of fine silt particles.||Coastal Engineering|
|Fine-grained sediment||In the Unified Soil Classification System (ASTM D2487), a soil material having 50 percent or more finer than the No. 200 (0.075 mm) U.S. standard sieve.||Coastal Engineering|
|Fine-material load||That part of the total sediment load that is composed of particles smaller than the particles present in appreciable quantities in the stream bed. Normally, that is of sediment particles smaller than 0.062 mm.||Coastal Engineering|
|Fines||(ASTM D 653) Portion of a soil finer than a No. 200 (75-µm) U.S. standard sieve.||Coastal Engineering|
|Finite element method||Method of solving the governing equations of a numerical model by dividing the spatial domain into elements in each of which the solution of the governing equations is approximated by some continuous function.||Coastal Engineering|
|Finite-difference model||A particular kind of digital computer model based upon a rectangular grid that sets the boundaries of the model and the nodes where the model will be solved.||Coastal Engineering|
|fiord (fjord)||See fjord.||Coastal Engineering|
|First reduction||A method of determining high and low water heights, time intervals, and ranges from an arithmetic mean without adjustment to a long-term series through simultaneous observational comparisons.||Coastal Engineering|
|Firth||A narrow arm of the sea; also, the opening of a river into the sea.||Coastal Engineering|
|Fish ladder||A fishway that provides passage over or around a vertical obstruction.||Coastal Engineering|
|Fishway||A structure designed to allow fish passage around, over, or through obstacles.||Coastal Engineering|
|Fitting losses||Sum total of head losses caused by elbows, valves, or other in-line fittings; minor losses in a dredging system.||Coastal Engineering|
|Fix||The instant at which the horizontal position of a receiving antenna location is observed.||Coastal Engineering|
|Fixed bed model||Model in which the bed and side materials are nonerodible; deposition does not occur either.||Coastal Engineering|
|Fjord||1. A long narrow winding inlet or arm of the sea, U-shaped and steep-walled, generally several hundred meters deep, between high rocky cliffs or slopes along a mountainous coast; typically with a shallow sill or threshold of solid rock or earth material submerged near its mouth, and becoming deeper inland. A fjord usually represents the seaward end of a deeply excavated glacial-trough valley that is partially submerged by drowning after the melting of the ice.||Coastal Engineering|
|Flagella||Whiplike structure that enables motility in certain groups of algae.||Coastal Engineering|
|Flanking||In towing vessel maneuver, maneuvering action of a downbound tow in a sharp bend. The engines are being reversed to check headway and keep the tow in the best water with room to slide sideways while floating around the turn until ready to pour on the power. The flanking rudders which are located forward of the wheels keep the tow in shape while the river current slowly pushes the tow around the bend. On an upbound tow navigating a sharp bend, the pilot will slow and hold the tow's head where he wants it, while flanking the whole tow sideways, then he slowly pushes ahead until clear.||Coastal Engineering|
|Flap gate||A gate hinged at the top and allowing flow in only one direction.||Coastal Engineering|
|Flap valve||A valve installed near the pump discharge which prevents a reverse flow in the discharge line from doing serious water hammer damage to the pump.||Coastal Engineering|
|Flash Flood||A flood that crests in a short length of time and is often characterized by high velocity flows.||Coastal Engineering|
|Flashboards||Boards or logs in a weir structure that are either added or removed to adjust the crest elevation of the weir.||Coastal Engineering|
|Flashiness||Term that describes the degree to which a watershed is able to attenuate the intensity of storm flows through infiltration, retention, detention, … A "flashy" watershed has a high degree of impervious surface resulting in fast, intense flood peaks.||Coastal Engineering|
|Flats||Areas of shallow water, or areas in the tidal zone, which are periodically covered with water.||Coastal Engineering|
|Flexible Connection||A connection such as rubber hoses swivel elbows, or ball joints, used to allow movement and flexibility between a fixed and moving section of pipe. (See flexible coupling; stern connection.)||Coastal Engineering|
|Flexible Coupling||Rubber hose or sleeve which connects the suction pipe to the hull of the hydraulic suction dredge. (See also bag; belly.)||Coastal Engineering|
|Float Well||A stilling well in which the float of a float-actuated tide gage operates. (See also stilling well.)||Coastal Engineering|
|Floating Breakwater||(EM 1110-2-5026) A temporary, floating structure made of foam-filled vehicle rubber tires. These form modules are erected and anchored in moderate wave energy areas to protect the shoreline and marsh plants establishing behind the breakwater.||Coastal Engineering|
|Floating line (coastal engineering)||Period when a tidal current is flowing towards the land.||Coastal Engineering|
|Floating Pipeline||See pipe.||Coastal Engineering|
|Floating Tire Breakwater||See breakwater.||Coastal Engineering|
|Floc||Loose, open-structured mass formed in a suspension by the aggregation of minute particles.||Coastal Engineering|
|Flocculation Agent||A coagulating substance which, when added to water, forms a flocculent precipitate that will entrain suspended matter and expedite settling; for example, alum, ferrous sulfate, or lime.||Coastal Engineering|
|Flocculation||The process of forming flocs.||Coastal Engineering|
|Flocculent||An agent that produces floes or aggregates from small suspended particles.||Coastal Engineering|
|Flood (coastal engineering)||Rising phase of the tidal cycle.||Coastal Engineering|
|Flood Attenuation||To lessen the amount, force or severity of high flows.||Coastal Engineering|
|Flood Axis||The average direction of the tidal current at strength of flood.||Coastal Engineering|
|Flood Channel||1. Channel located on ebb-tidal shoal that carries the flood tide over the tidal flat into the back bay or lagoon.||Coastal Engineering|
|Flood control||The use of techniques to change the physical characteristics of floods.||Coastal Engineering|
|Flood Current (flood)||The movement of a tidal current toward the shore or up a tidal river or estuary. In the mixed type of reversing current, the terms greater flood and lesser flood are applied respectively to the two flood currents of greater and lesser speed of each day. The expression maximum flood is applicable to any flood current at the time of greatest speed. (See also flood strength.)||Coastal Engineering|
|Flood Current||The movement of a tidal current toward the shore or up a tidal stream. In the semidiurnal type of reversing current, the terms greater flood and lesser flood are applied respectively to the flood currents of greater and lesser velocity each day. The terms maximum flood and minimum flood are applied to the maximum and minimum velocities of a flood current the velocity of which alternately increases and decreases without coming to slack or reversing. The expression maximum flood is also applicable to any flood current at the time of greatest velocity.||Coastal Engineering|
|Flood Delta||A tidal delta generated by flood currents, located on the landward side of an inlet. Syn: flood-tidal delta, flood-tidal shoals.||Coastal Engineering|
|Flood Diversion Channel||See floodway.||Coastal Engineering|
|Flood evacuation||Removal of people and property at flood risk following a warning.||Coastal Engineering|
|Flood forecasting||Prediction of the characteristics of an imminent future flood.||Coastal Engineering|
A gravity outlet fitted with vertically-hinged doors, opening if the inner water level is higher than the outer water level, so that drainage takes place during low water.
|Flood Interval||The interval between the transit of the moon over the meridian of a place and the time of the following flood.||Coastal Engineering|
|Flood Mark||Proof of any kind on the shoreline, or on structures like bridge abutments, used to determine the highest level attained by the water surface during the flood (note: the height of the flood mark usually includes the wave run-up).||Coastal Engineering|
|Flood of Record||The highest flood historically recorded in a given location.||Coastal Engineering|
|Flood Peak||The highest value of stage or discharge achieved by a flood. Flood crest is equivalent to peak stage.||Coastal Engineering|
|Flood Plain||1. A flat tract of land bordering a river, mainly in its lower reaches, and consisting of ALLUVIUM deposited by the river. It is formed by the sweeping of the meander belts downstream, thus widening the valley, the sides of which may become some kilometers apart. In time of flood, when the river overflows its banks, sediment is deposited along the valley banks and plains.||Coastal Engineering|
|Flood Pool||A volume of space in a reservoir reserved for storage of flood waters.||Coastal Engineering|
|Flood Ramp||Seaward-dipping sand platform dominated by flood-tidal currents, located on ebb-tidal shoal near the opening to the inlet.||Coastal Engineering|
The determination of the attenuating effect of storage on a river-flood passing through a valley by reason of a feature acting as control (e.g. a reservoir with a spillway capacity less than the flood inflow, or the widening or narrowing of a valley).
|Flood Stage||The gage height at which the stream begins to overflow its banks.||Coastal Engineering|
|Flood standard||The flood selected for planning purpose.||Coastal Engineering|
Parts of the floodplains which are important for the temporary storage of floodwater during the passage of a flood.
|Flood Strength (strength of flood)||Phase of the flood tidal current at the time of maximum speed. Also, the speed at this time. (See also strength of current.)||Coastal Engineering|
|Flood study||A comprehensive technical investigation of flood behavior.||Coastal Engineering|
|Flood Tidal Delta||The bulge of sand formed at the landward mouth of TIDAL INLETS as a result of flow expansion.||Coastal Engineering|
|Flood Tide||The period of tide between low water and the succeeding high water; a rising tide.||Coastal Engineering|
|Flood Wall (splash wall)||Wall, retired from the seaward edge of the seawall crest, to prevent water from flowing onto the land behind.||Coastal Engineering|
|Flood||1. Period when tide level is rising; often taken to mean the flood current which occurs during this period.||Coastal Engineering|
|Floodplain Bench||A small level area that forms at the effective discharge stage within an over-wide, entrenched channel.||Coastal Engineering|
|Floodplain||Normally dry land adjacent to a body of water such as a river, stream, lake, or ocean, which is susceptible to inundation by floodwaters.||Coastal Engineering|
|Flood-prone Area||A term coined by Rosgen (1996) to describe the area flooded at flows twice the maximum depth of flow at the effective discharge.||Coastal Engineering|
|Floodwall||A wall constructed of masonry or concrete to provide flood protection from seasonal high water.||Coastal Engineering|
|Floodway||A natural or constructed channel that conveys flood flows.||Coastal Engineering|
|Flora||The entire group of plants found in an area.||Coastal Engineering|
|Florida Current||A North Atlantic Ocean current setting northward along the southeast coast of the United States. A segment of the Gulf Stream System, the Florida Current extends from the Straits of Florida to the region off Cape Hatteras.||Coastal Engineering|
|Flow (steady)||The flow that occurs when, at any point in the flow field, the magnitude and direction of flow are constant in time.||Coastal Engineering|
|Flow (unsteady)||Also called transient flow. The flow that occurs when, at any point in the flow field, the magnitude or direction of flow changes with time.||Coastal Engineering|
|Flow Attenuation||See Flood Attenuation.||Coastal Engineering|
A measure of the range and variability of a stream’s flow. The flow duration curve represents the percent of time during which specified flow rates are exceeded at a given location. This is usually presented as a graph of flow rate (discharge) versus percent of time that flows are greater than, or equal to, that flow.
|Flow Fields||The domain in which the water flows.||Coastal Engineering|
|Flow Meter||A device that measures the velocity of fluid (dredge slurry) in a pipe.||Coastal Engineering|
|Flow Net||The set of intersecting equipotential lines and flowlines representing two-dimensional steady flow through porous media.||Coastal Engineering|
|Flow Rate||A common term for discharge (Length3/time), or total flow, or volume of water across a given measurement location.||Coastal Engineering|
|Flow||The British equivalent of the United States total current. Flow is the combination of their tidal stream and current.||Coastal Engineering|
|Flowability||The facility of a sloped soil deposit to fail and flow into an excavation at its lowest end; the instability of a sloped soil.||Coastal Engineering|
|Fluff||See fluid mud.||Coastal Engineering|
|Fluid Mud||A material which is a mixture of fine sand, silt, and/or clay soil; typically found at the surface of the bottom in harbors and other areas of slow current and which has a fluid consistency. (See also consistency.)||Coastal Engineering|
|Flume||An open channel constructed of wood, steel, or reinforced concrete and used to convey water for various purposes, including grade control.||Coastal Engineering|
|Flushing Rate||The retention time (turnover rate or flushing rate), the average length of time water resides in a lake, ranging from several days in small impoundments to many years in large seepage lakes. Retention time is important in determining the impact of nutrient inputs. Long retention times result in recycling and greater nutrient retention in most lakes. Calculate retention time by dividing the volume of water passing through the lake per year by the lake volume.||Coastal Engineering|
|Flushing Time||The time required to replace all the water in an ESTUARY, HARBOR, etc., by action of current and tide.||Coastal Engineering|
|Fluvial Sediment||Particles derived from rocks or biological materials which are transported by, suspended in, or deposited by streams.||Coastal Engineering|
|Fluvial||Of or pertaining to rivers; produced by the action of a river or stream (e.g., fluvial sediment).||Coastal Engineering|
|Foam Line||1. The front of a wave as it advances shoreward, after it has broken.||Coastal Engineering|
|Following Wind||Generally, the same as a tailwind; in wave forecasting, wind blowing in the direction of ocean-wave advance.||Coastal Engineering|
|Food Chain||The transfer of food energy from plants through herbivores to carnivores. An example: insect-fish-bear or the sequence of algae being eaten by zooplankton (grazers; herbivores) which in turn are eaten by small fish (planktivores; predators) which are then eaten by larger fish (piscivores; fish eating predators) and eventually by people or other predators (fish-eating birds, mammals, and reptiles).||Coastal Engineering|
|Food Web||Food chains hooked together into a complex interconnected web.||Coastal Engineering|
|Forced Wave||A wave generated and maintained by a continuous force.||Coastal Engineering|
|Fore Reef||The seaward side of a REEF (usually coral); in places a steep slope covered with reef talus.||Coastal Engineering|
|Forebay||The impoundment of water above a dam or hydroelectric plant.||Coastal Engineering|
|Foredune||The front DUNE immediately behind the backshore.||Coastal Engineering|
|Forerunner||Low, long-period ocean SWELL which commonly precedes the main swell from a distant storm, especially a tropical cyclone.||Coastal Engineering|
|Foreset (bed)||Inclined layers of a cross-bedded unit, specifically on the frontal slope of a delta or the lee of a dune.||Coastal Engineering|
|Foreset Bed||Included layers of sandy material deposited upon or along an advancing and relatively steep frontal slope. A foreset bed progressively covers a bottomset bed, and in turn is covered by a topset bed.||Coastal Engineering|
|Foreshore||The part of the shore, lying between the crest of the seaward berm (or upper limit of wave wash at high tide) and the ordinary low water mark, that is ordinarily traversed by the uprush and backrush of the waves as the tides rise and fall.||Coastal Engineering|
|Forestry Use||The beneficial use of dredged material sites for the production of timber and timber products such as cottonwood or eucalyptus tree plantations. (See also beneficial uses.)||Coastal Engineering|
|Form Liner||A liner for concrete forms designed to produce a special finish.||Coastal Engineering|
|Formal Advertising||Procurement by competitive bids and awards; involves basic steps of (1) invitation for bids, (2) publicizing the invitation, (3) submission of bids by prospective contractors, and (4) awarding the contract.||Coastal Engineering|
|Rate of movement (propagation) of the hurricane eye in meters per second, knots, or miles per hour.||Coastal Engineering|
|Foundation Drainage System||A line of holes drilled downstream of the grout curtain designed to intercept and control seepage through or beneath a dam so as to reduce uplift pressures under a dam||Coastal Engineering|
|Foundation||The surface and the natural material on which a dam and appurtenant features are constructed.||Coastal Engineering|
|Fourier Series||A series proposed by the French mathematician Fourier about the year 1807. The series involves the sines and cosines of whole numbers of a varying angle and is usually written in the following form y = H0 + A1sin x + A2sin 2x + A3sin 3x + B1cos x + B2cos 2x + B3cos 3x + ... By taking a sufficient number of terms the series may be made to represent any periodic function of x.||Coastal Engineering|
|Free Wave||A wave that continues to exist after the generating force has ceased to act.||Coastal Engineering|
|Freeboard||At a given time, the vertical distance between the water level and the top of the structure. On a ship, the distance from the waterline to main deck or gunwale.||Coastal Engineering|
|Free-surface Flow||A fluctuating water surface elevation. A numerical model which can calculate a changing water surface elevation is a free-surface model. Models designated as "rigid lid" do not permit free-surface calculations.||Coastal Engineering|
|Frequency Band||A particular range of frequencies.||Coastal Engineering|
|Frequency Spectrum||The distribution of signal amplitudes as a function of frequency.||Coastal Engineering|
|Frequency||The number of repetitions of a random process in a certain time period.||Coastal Engineering|
|Friability||The ease with which a soil will crumble or pulverize upon cutting or crushing.||Coastal Engineering|
|Soil that exhibits the property of friability; soil having a low plasticity index, including gravel, sand, some silts, mica, diatoms, and peat. (See also friability.)||Coastal Engineering|
|Fringing Islands||A series of islands that fringe, or mask, a mainland coast often known as BARRIER ISLANDS. The waters landward of such islands are sometimes treated as high seas enclaves or as inland waters.||Coastal Engineering|
|Fringing Reef||A coral REEF attached directly to an insular or continental shore. There may be a shallow channel or lagoon between the reef and the adjacent mainland.||Coastal Engineering|
|Front of the Fetch||In wave forecasting, the end of the generating area toward which the wind is blowing.||Coastal Engineering|
|Frontal Passages||As in weather; refers to a meteorological storm front.||Coastal Engineering|
Number Model (or gravitational model)
|Model designed to emphasize similarity of gravitational and inertial forces (Froude Number), while other forces such as viscous (Reynolds Number) may not be reproduced as accurately. Open channel and coastal models are of this type.||Coastal Engineering|
|Froude Number||U/(g·L)1/2 (U = velocity, g = gravity, L = length). A dimensionless number expressing the ratio between the influences of inertia and gravity in a fluid. The Froude number is important wherever the gravity effect is dominating, such as with water waves, flow in open channels, sedimentation in lakes and reservoirs, salt-water intrusions, and the mixing of air masses of different densities.||Coastal Engineering|
|Fruehling Draghead||See drag head.||Coastal Engineering|
|Fuel Barge||See barge.||Coastal Engineering|
|Fully-developed Sea||The waves that form when wind blows for a sufficient period of time across the open ocean. The waves of a fully developed sea have the maximum height possible for a given wind speed, FETCH and duration of wind.||Coastal Engineering|
|Functional Life||The period of time during which a structure performs as intended. Performance can be expressed in terms of benefits obtained versus the cost of installation and maintenance.||Coastal Engineering|
|Fyord||See fjord||Coastal Engineering|
back to top
1. Steel wire-mesh basket to hold stones or crushed rock to protect a bank or bottom from erosion.
2. Structures composed of masses of rocks, rubble or masonry held tightly together usually by wire mesh so as to form blocks or walls. Sometimes used on heavy erosion areas to retard wave action or as a foundation for BREAKWATERS or JETTIES.
|Gage datum||Elevation of the zero point of the reference gage from which gage height is determined as compared to sea level.||Coastal Engineering|
|Gage height||Water-surface elevation referenced to the gage datum.||Coastal Engineering|
|Gage||See gauge; tide gage.||Coastal Engineering|
|Gaging station||A selected cross section of a stream channel where one or more variables are measured continuously or periodically to record discharge and other parameters.||Coastal Engineering|
|Gaining stream||A stream or reach of stream whose flow is being increased due to an inflow of ground water.||Coastal Engineering|
A wind between a strong breeze and a storm. A continuous wind blowing in degrees of moderate, fresh, strong, or whole gale and varying in velocity from 28 to 47 nautical miles per hour (see BEAUFORT SCALE).
Synonym : Beaufort Scale
|Gallery||A long, narrow passage inside a dam used for access, inspection, grouting, or drilling of drain holes.||Coastal Engineering|
|Gamma-gamma radiation log||A borehole log in which a source of gamma radiation as well as a detector are lowered into the borehole. This log measures bulk density of the formation and fluids.||Coastal Engineering|
|Gantry||A large structure located at the stern of a hydraulic cutter dredge which is used to support and lift the spuds||Coastal Engineering|
|Gas ejectors||A system utilized to remove gases from within the suction line of a hydraulic dredge before it can collect in the pump and cause the pump to lose its prime.||Coastal Engineering|
|Gas purged pressure gage||A type of analog tide gage in which gas, usually nitrogen, is emitted from a submerged tube at a constant rate. Fluctuations in hydrostatic pressure due to changes in tidal height modify the emission rate for recording. Also called a bubbler tide gage.||Coastal Engineering|
|Gas Solubility||The ability of a gas to dissolve into another substance.||Coastal Engineering|
1. An instrument for measuring the water level relative to a datum or for measuring other parameters.
2. A vertical measuring device to determine the height of a river above its bottom or some fixed point. (USACE)
|General and administrative overhead||Costs frequently referred to as home office expense; usually these costs are incurred elsewhere other than at the job site; general costs of doing business.||Coastal Engineering|
|Generating area||In wave forecasting, the continuous area of water surface over which the wind blows in nearly a constant direction. Sometimes used synonymously with FETCH LENGTH. Also FETCH.||Coastal Engineering|
|Generation of waves|
1. The creation of waves by natural or mechanical means.
2. The creation and growth of waves caused by a wind blowing over a water surface for a certain period of time. The area involved is called the GENERATING AREA or FETCH.
|Geochronology||The study of time in relationship to the history of the earth. Encompasses radiometric and non-radiometric techniques to date sediments and strata.||Coastal Engineering|
|Geodetic coordinates||(EM 1110-2-1003) Angular latitudinal and longitudinal coordinates, usually referenced to some defined ellipsoid of revolution. (also, geographical coordinates).||Coastal Engineering|
|Geodetic datum||See National Geodetic Vertical Datum of 1929; National Geodetic Vertical Datum.||Coastal Engineering|
|Geographic Information System (GIS)||A computer system which allows for input and manipulation of geographic data to allow researchers to manipulate, analyze and display the information in a map format.||Coastal Engineering|
|Geographic mile||Unit of linear measure equal to one minute of latitude at the equator. See NAUTICAL MILE.||Coastal Engineering|
|Geographic range||The greatest distance the curvature of the earth permits an object of a given height to be seen from a particular height of eye without regard to luminous intensity or visibility conditions.||Coastal Engineering|
|Geographical coordinates||See geodetic coordinates.||Coastal Engineering|
|Geologic Control||A local rock formation or clay layer that limits (within the engineering time frame) the vertical and/or lateral movement of a stream at a particular point. Note that artificial controls such as drop structures also exist.||Coastal Engineering|
|Geologic erosion||The erosion process on a given land form that is not associated with the activities of man.||Coastal Engineering|
|Geology||A science that deals with the physical history of the earth, especially as recorded in rocks and landforms.||Coastal Engineering|
|Geometric dilution of precision||(EM 1110-2-1003) A statistic used to measure the geometrical effects on the accuracy of a coordinated point from the intersection of lines, circles, spheres, hyperbolas, etc.||Coastal Engineering|
|Geometric grade scale||A grade scale having a constant ratio between size classes (e.g., the Wentworth grade scale), each size class of which differs from its predecessor by the constant ratio 1/2.||Coastal Engineering|
|Geometric mean diameter||The diameter equivalent of the arithmetic mean of the logarithmic frequency distribution. In the analysis of beach sands, it is taken as that grain diameter determined graphically by the intersection of a straight line through selected boundary sizes, (generally points on the distribution curve where 16 and 84 percent of the sample is coarser by weight) and a vertical line through the median diameter of the sample.||Coastal Engineering|
|Geometric mean||The nth root of the product of the values of n positive numbers; the antilogarithm of the mean of the logarithms of individual values.||Coastal Engineering|
|Geometric shadow||In wave diffraction theory, the area outlined by drawing straight lines paralleling the direction of wave approach through the extremities of a protective structure. It differs from the actual protected area to the extent that the diffraction and refraction effects modify the wave pattern.||Coastal Engineering|
|Geometric Similarity||Similarity in form or shape.||Coastal Engineering|
|Geomorphological||The study of physical systems of the earth.||Coastal Engineering|
|Geomorphology||The study of landform development under processes associated with running water.||Coastal Engineering|
|Geophysics||The study of the physical characteristics and properties of the earth, usually employing quantitative physical methods.||Coastal Engineering|
|Geopotential (equipotential) surface||A surface that is everywhere normal to the acceleration of gravity.||Coastal Engineering|
|Geopotential anomaly||The excess in geopotential difference over the standard geopotential difference [at a standard specific volume at 35 parts per thousand (0/00) and 0 degrees C] between isobaric surfaces. (See also geopotential;||Coastal Engineering|
|Geopotential difference||The work per unit mass gained or required in moving a unit mass vertically from one geopotential surface to another. (See also geopotential; geopotential anomaly; geopotential topography.)||Coastal Engineering|
|Geopotential topography||The topography of an equiscalar (usually isobaric) surface in terms of geopotential difference. As depicted on maps, isopleths are formed by the intersection of the isobaric surface with a series of geopotential surfaces. Thus, the field of isopleths represents variations in the geopotential anomaly of the isobaric surface above a chosen reference isobaric surface (such as a level of no motion).||Coastal Engineering|
|Geopotential||The unit of geopotential difference, equal to the gravity potential of 1 meter squared per second squared, m2/s2, or 1 joule per kilogram, J/kg.||Coastal Engineering|
|Geostrophic flow||A solution of the relative hydrodynamic equations of motion in which it is assumed that the horizontal component of the Coriolis force is balanced by the horizontal component of the pressure gradient force.||Coastal Engineering|
|Geotechnical engineering||That branch of the science, and art, of civil engineering in which the allied sciences of soil mechanics and rock mechanics, using the laws of mechanics and hydraulics, are used to solve engineering problems associated with soils and rock.||Coastal Engineering|
|Geotechnical investigations||(EM 1110-2-1003) Subsurface investigation of soils, rock, and other strata for the purposes of engineering design.||Coastal Engineering|
|Geotextile||A synthetic fabric which may be woven or non-woven used as a filter.||Coastal Engineering|
|Ghyben-herxberg principle||An equation that relates the depth of a saltwater interface in a coastal aquifer to the height of the freshwater table above sea level.||Coastal Engineering|
|Gimbal||As used in a dragarm - flexible, universal joint usually located at the midpoint of a dragarm.||Coastal Engineering|
|Glacial outwash||Well-sorted sand, or sand and gravel, deposited by the meltwater from a glacier.||Coastal Engineering|
|Glacial till||Unsorted and unstratified deposits by melting ice without reworking by meltwater. Till may consist of a mixture of clay, silt, sand, gravel, and boulders.||Coastal Engineering|
A large mass of ice formed, at least in part, on land by the compaction and recrystallization of snow, moving slowly by creep downslope or outward in all directions due to the stress of its own weight, and surviving from year to year. Included are small mountain glaciers as well as ice sheets continental in size, and ice shelves which float on the ocean but are fed in part by ice formed on land.
A large body of ice moving slowly down a slope of valley or spreading outward on a land surface (e.
g., Greenland, Antarctica) and surviving from year to year.
|Glacio-eustasy||The worldwide changes in sea level produced by the successive withdrawal and return of water in the oceans accompanying the formation and melting of ice sheets.||Coastal Engineering|
|Glacio-isostacy||The state of hydrostatic equilibrium of the earth's crust as influenced by the weight of glacier ice.||Coastal Engineering|
Shallow, low gradient stream sections with slow current and fine substrate.
|Global positioning system (GPS)||A navigational and positioning system developed by the U.S. Department of Defense, by which the location of a position on or above the Earth can be determined by a special receiver at that point interpreting signals received simultaneously from several of a constellation of special satellites.||Coastal Engineering|
|Global warming||The increase in the earth’s temperature due to the emissions of greenhouse gases.||Coastal Engineering|
|Gong||A wave actuated sound signal on buoys which uses a group of saucer- shaped bells to produce different tones.||Coastal Engineering|
|Gorge||1. The deepest portion of an inlet, the THROAT.|
2. A narrow, deep valley with nearly vertical rock walls.
|Government approval||Approval of a process, descriptive data, drawing, or other documents by the contracting officer if required by the contract.||Coastal Engineering|
|Government estimate||An independent estimate of time and cost prepared by the Government prior to accomplishing an item of work either with Government plant and labor or entering into an agreement with a private contractor for accomplishing the work. (EFARS 36.203) Cost est||Coastal Engineering|
|Government-caused delay||An action or nonaction by the government which results in a significant delay of a contractor's scheduled progress in completing work required under a contract. This is an excusable delay.||Coastal Engineering|
|Government-furnished equipment||Equipment in the possession of or acquired directly by the government and subsequently delivered to or made available to the contractor for use or for incorporation into the work.||Coastal Engineering|
|Government-furnished property, gfp||That property or equipment to be furnished to the contractor at a specified location and at a specified time by the government at no cost to the contractor.||Coastal Engineering|
|Grab dredge||See dredge, mechanical, cable excavator, clamshell.||Coastal Engineering|
|Gradation curve||See particle-size distribution.||Coastal Engineering|
|Gradation||(ASTM D 653) The proportions by mass of a soil or fragmented rock distributed in specified particle-size ranges.||Coastal Engineering|
|Any of several types of structures used to control channel gradient.||Coastal Engineering|
|Grade scale||A systematic, arbitrary division of an essentially continuous range of particle sizes (of a soil, sediment, or rock) into a series of classes or scale units (or grades) for the purposes of standardization of terms and of statistical analysis; it is usually logarithmic.||Coastal Engineering|
|Grade||(Huston. Hydraulic Dredging Principles...) Contract depth.||Coastal Engineering|
|Graded bedding||An arrangement of particle sizes within a single bed, with coarse grains at the bottom of the bed and progressively finer grains toward the top of the bed.||Coastal Engineering|
|Graded shoreline||A shoreline that has been straightened or simplified by the formation of barriers across embayments and by the cutting-back of headlands, and that possesses a broadened surface profile so adjusted in slope that the energy of incoming waves is completely absorbed and the shifting of the shoreline is reduced to a very slow rate; a shoreline with a vertical profile of equilibrium, typical of an advanced stage of development.||Coastal Engineering|
|Graded||1. An engineering term pertaining to a soil or an unconsolidated sediment consisting of particles of several or many sizes or having a uniform or equable distribution of particles from coarse to fine (e.g., a ''graded sand'' containing coarse, medium, and fine particle sizes).|
2. A geologic term pertaining to an unconsolidated sediment or to a cemented detrital rock consisting of particles of essentially uniform size or of particles lying within the limits of a single grade.
|Gradient flow||A solution of the relative hydrodynamic equations of motion in which only the horizontal Coriolis, pressure gradient, and centrifugal forces are considered.||Coastal Engineering|
|Gradient||1. A measure of slope (soil- or water-surface) in meters of rise or fall per meter of horizontal distance.|
2. More general, a change of a value per unit of distance, e.g. the gradient in longshore transport causes erosion or accretion.
3. With reference to winds or currents, the rate of increase or decrease in speed, usually in the vertical; or the curve that represents this rate.
1. Degree of mixing of size classes in sedimentary material - Well graded implies a more or less uniform distribution from coarse to fine; poorly graded implies uniformity in size of lack of continuous distribution.
2. Distribution, with regard to size or weight, of individual stones within a bulk volume; heavy, light and fine grading are distinguished.
|Gradual closure method||Method in which the final closure gap in a dam is closed gradually either by the vertical or horizontal closure method; this in contradiction with a sudden closure.||Coastal Engineering|
|Grain size||See particle size.||Coastal Engineering|
|Grain||Size distribution||Coastal Engineering|
|Grain-size analysis||(ASTM D 653) The process of determining grain-size distribution.||Coastal Engineering|
|Granite||A very hard, crystalline, plutonic rock, gray to pink in color, consisting of feldspar, quartz, and smaller amounts of other minerals.||Coastal Engineering|
|Granular filter||Band of granular material which is incorporated in an embankment, dam, dike, or bottom protection and is graded so as to allow seepage to flow across or down the filter zone without causing the migration of the material adjacent to the filter.||Coastal Engineering|
|See dredge, mechanical, cable excavator, grapple bucket.||Coastal Engineering|
|Grapple||Hook or an iron instrument, when combined with an fastening line, by which one item, as a ship, fastens onto another.||Coastal Engineering|
|Graticule||The network of lines representing meridians and parallels on a map, chart, or hydrographic survey field or smooth sheet.||Coastal Engineering|
|Gravel size||Rock fragments or particles that will pass a 3-in. (76.2 mm) and be retained on a No. 4 (4.75 mm) U.S. standard sieve.||Coastal Engineering|
|Gravel||Unconsolidated natural accumulation of rounded rock fragments coarser than sand but finer than pebbles (2-4 mm diameter).||Coastal Engineering|
|Gravitational tide||See equilibrium tide.||Coastal Engineering|
|Gravity potential||A potential due to the position of groundwater or soil moisture above a datum.||Coastal Engineering|
|Gravity wave||A wave whose velocity of propagation is controlled primarily by gravity. Water waves more than 5 cm long are considered gravity waves. Waves longer than 2.5 cm and shorter than 5 cm are in an indeterminate zone between CAPILLARY and GRAVITY WAVES.||Coastal Engineering|
|Grazers||Herbivores; zooplankton in the open water zone.||Coastal Engineering|
diurnal range (gt)
|The difference in height between mean higher high water and mean lower low water. The expression may also be used in its contracted form, diurnal range.||Coastal Engineering|
|Great tropic range (gc)||The difference in height between tropic higher high water and tropic lower low water. The expression may also be used in its contracted form, tropic range.||Coastal Engineering|
|Greenbelt||A linear park, usually located along a stream corridor or other right-of-way.||Coastal Engineering|
|Greenhouse||Gas particularly carbon dioxide (CO2), methane (CH4), oxides of nitrogen (NO2, NO3) and CFCs (chlorofluorocarbons).||Coastal Engineering|
|Greentree reservoir||A shallow reservoir in which water levels are manipulated for wildlife and timber production.||Coastal Engineering|
|Greenwich argument||Equilibrium argument computed for the meridian of Greenwich.||Coastal Engineering|
|Greenwich epoch||See epoch (1).||Coastal Engineering|
|Greenwich interval||An interval referred to the transit of the Moon over the meridian of Greenwich as distinguished from the local interval which is referred to the Moon's transit over the local meridian. The relation in hours between Greenwich and local intervals may be expressed by the formula Greenwich interval = local interval + 0.069 L||Coastal Engineering|
|Mean solar time at the meridian of Greenwich, England. It has been used as a basis for standard time throughout the world. Also called Zulu time.||Coastal Engineering|
|Gregorian calendar||The modern calendar in which every year divisible by 4 (excepting century years) and every century year divisible by 400 are bissextile (or leap) years with 366 days. All other years are common years with 365 days. The average length of the year is, therefore, 365.2425 days which agrees very closely with the length of the tropical year (the period of changes in the seasons). The Gregorian calendar was introduced by Pope Gregory in 1582, and immediately adopted by the Catholic countries in place of the Julian calendar previously in use.|
In making the change it was ordered that the day following October 4, 1582, of the Julian calendar be designated October 15, 1582, of the Gregorian calendar -- the 10 days being dropped in order that the vernal equinox would fall on March 21. The Gregorian calendar was not adopted by England until 1752, but is now in general use throughout the world.
|Grid||Network of points covering the space or time-space domain of a numerical model. The points may be regularly or irregularly spaced.||Coastal Engineering|
|Groin bay||The beach compartment between two groins.||Coastal Engineering|
|Groin field||(NAVFAC DM-26.3) A series of groins acting together to protect a section of beach.||Coastal Engineering|
|Groin system||A series of groins acting together to protect a section of beach. Commonly called a groin field.||Coastal Engineering|
|Groin||1. (British, GROYNE) - A shore protection structure built (usually perpendicular to the shoreline) to trap littoral drift or retard erosion of the shore.|
2. Narrow, roughly shore-normal structure built to reduce longshore currents, and/or to trap and retain littoral material. Most groins are of timber or rock and extend from a SEAWALL, or the backshore, well onto the foreshore and rarely even further offshore.
|Gross erosion||The total of all sheet, gully, and channe1 erosion in a drainable basin, usually expressed in units of weight.||Coastal Engineering|
|Ground motion||A general term including all aspects of ground motion, namely particle acceleration, velocity, or displacement, from an earthquake or other energy source.||Coastal Engineering|
|Ground-penetrating radar||A surface geophysical technique based upon the transmission of repetitive pulses of electromagnetic waves into the ground. Some of the radiated energy that is reflected back to the surface is captured and processed.||Coastal Engineering|
|Groundwater divide||The boundary between two adjacent groundwater basins. The divide is represented by a high in the water table.||Coastal Engineering|
|Groundwater flow model||An application of a mathematical model to represent a site-specific groundwater flow system.||Coastal Engineering|
|Groundwater||The water contained in interconnected pores located below the water table.||Coastal Engineering|
|Grout curtain||A row of holes filled with grout under pressure near the heel of the dam to control seepage under the dam.||Coastal Engineering|
|Grout||A mixture of water and cement or a chemical solution that is forced by pumping into foundation rocks or joints in a dam to prevent seepage and to increase strength.||Coastal Engineering|
|Guiana current||An Atlantic Ocean current setting northwestward along the northeast coast of South America.||Coastal Engineering|
|Guinea current||An Atlantic Ocean current setting eastward along the west central coast of Africa. A continuation of the Equatorial Counter Current of the Atlantic Ocean.||Coastal Engineering|
|Gulder||Local name given to the double low water occurring on the south coast of England. (See also double tide.)||Coastal Engineering|
|Gulf coast low water datum line||The line on a chart or map which represents the intersection of the land with the water surface at the elevation of Gulf Coast Low Water Datum.||Coastal Engineering|
|Gulf coast low water datum, gclwd||A tidal datum. Used as chart datum from November 14, 1977 to November 27, 1980, for the coastal waters of the gulf coast of the United States. GCLWD is defined as mean lower low water when the type of tide is mixed and mean low water (now mean lower low water) when the type of tide is diurnal. (See also National Tidal Datum Convention of 1980.)||Coastal Engineering|
|Gulf stream system||The continuous current system composed of the Florida Current, Gulf Stream, and North Atlantic Current.||Coastal Engineering|
|Gulf stream||A North Atlantic Ocean current setting northeastward off the east coast of the United States. A segment of the Gulf Stream System, the Gulf Stream extends from the region off Cape Hatteras to an area southeast of the Grand Banks at about latitude 40? north, longitude 50? west. It continues the flow of the Florida Current to the North Atlantic Current.||Coastal Engineering|
|Gulf||A relatively large portion of the ocean or sea extending far into land; the largest of various forms of inlets of the sea (e.g., Gulf of Mexico, Gulf of Aqaba).||Coastal Engineering|
|Gut||A tidal stream connecting two larger waterways.||Coastal Engineering|
|Gyro compass||A device installed on large hydraulic dredges to provide accurate angular data for determining how much swing the dredge is making; use dictionary definition also.||Coastal Engineering|
back to top
|H||Rate of change (as of January 1, 1900) in mean longitude of Sun. h = 0.04106864 deg per solar hour||Coastal Engineering|
Deliberate and wise actions taken on dredged material disposal sites for the purpose of managing for plant or animal populations or communities or for target wildlife or fish species. (See also beneficial uses.)
Synonym : Beneficial Uses
|Habitat||The physical location in which a population of plants or animals lives.||Coastal Engineering|
|Hach Water Quality Test Kits|
Hach, Inc. (Website: http://www.hach.com/) is one of a number of companies that market a variety of test kits and field and lab instruments for water quality testing. Additional companies commonly cited are LaMotte and CHEMetrics, and there are probably numerous others accessible to the reader through various educational resources or scientific lab products catalogues. Water on the Web does not endorse any particular company’s products. Some test kits have been "approved" by state or federal agencies for certain types of tests in specific types of water or wastewater.
|Halcocline||A zone in which salinity changes rapidly.||Coastal Engineering|
|Half life||The time required for half of the atoms of a radioactive element to disintegrate into atoms of another element.||Coastal Engineering|
|Half-tide level||A plane midway between MEAN HIGH WATER and MEAN LOW WATER, also called MEAN TIDE LEVEL.||Coastal Engineering|
|Halocline||A layer in which the salinity changes significantly (relative to the layers above and below) with depth.||Coastal Engineering|
|Harbor oscillation (Harbor surging)||The nontidal water movement in a harbor or bay. Usually the motions are low, but when oscillations are excited by a tsunami or storm surge, they may be quite large. Variable winds, air oscillations, or surf beat also may cause oscillations. See SEICHE.||Coastal Engineering|
|Harbor||(British, HARBOUR) - Any protected water area affording a place of safety for vessels. See also PORT.||Coastal Engineering|
|Hard defenses||General term applied to impermeable coastal defense structures of concrete, timber, steel, masonry, etc, which reflect a high proportion of incident wave energy.||Coastal Engineering|
|Hard facing||Build-up welding in areas of heavy pump wear, particularly the welded parts of the pump system such as the pump shell, pipeline, fittings, runners, and cutters||Coastal Engineering|
|Hard point||A slope protection technique whereby "soft" or erodible materials are removed from a bank and replaced by stone or compacted clay. These features may also occur naturally along banks where currents have removed erodible materials leaving nonerodible materials exposed.||Coastal Engineering|
|Hardground||A zone at the sea bottom where the sediment is lithified to form a hardened surface, often encrusted, discolored, case-hardened, bored, and solution-ridden; such as a reef, rocky bed, or coral. Syn: hardbottom.||Coastal Engineering|
|Hardness||Resistance of a material to indentation or scratching.||Coastal Engineering|
|Hardpan||A hard impervious layer, composed chiefly of clay, cemented by relatively insoluble materials, that does not become plastic when mixed with water and definitely limits the downward movement of water and roots.||Coastal Engineering|
|Hardwater||Lakes that have a high buffering capacity and are not generally sensitive to acid deposition. These lakes have dissolved salt concentrations greater than 120 mg/L.||Coastal Engineering|
|Harmonic analysis||The mathematical process by which the observed tide or tidal current at any place is separated into basic harmonic constituents.||Coastal Engineering|
|Harmonic analyzer||A machine designed for the resolution of a periodic curve into its harmonic constituents. Now performed by electronic digital computer.||Coastal Engineering|
|Harmonic constants||The amplitudes and epochs of the harmonic constituents of the tide or tidal current at any place.||Coastal Engineering|
|Harmonic constituents||The component tides are usually referred to as harmonic constituents. The principal harmonic constituents of the tide are --. The routine prediction of tides is based upon a simple principle which asserts that for any linear system whose forcing can be.||Coastal Engineering|
|Harmonic function||In its simplest form, a quantity that varies as the cosine of an angle that increases uniformly with time. It may be expressed by the formula y = A cos at in which y is a function of time (t), A is a constant coefficient, and a is the rate of change in the angle at.||Coastal Engineering|
|Harmonic prediction||Method of predicting tides and tidal currents by combining the harmonic constituents into a single tide curve. The work is usually performed by electronic digital computer.||Coastal Engineering|
|Harmonic reduction||See harmonic analysis.||Coastal Engineering|
|Harmonic tide plane||See Indian spring low water.||Coastal Engineering|
|Hattush-jacob formula||An equation to describe the change in hydraulic head with time during pumping of a leaky confined aquifer.||Coastal Engineering|
|Haul distance||The one-way distance the hopper dredge must travel to a disposal area after filling its hopper at the dredging site.||Coastal Engineering|
|Head of rip||1.The part of a rip current that has widened out seaward of the breakers.||Coastal Engineering|
|Head of tide||The location up river where the tidal signal has been damped so that it is insignificant.||Coastal Engineering|
|Head, total hydraulic||The sum of the elevation head, the pressure head, and the velocity head at a given point in an aquifer.||Coastal Engineering|
|Head||The difference in elevation between two water surfaces.See hydraulic head.||Coastal Engineering|
|Headcut||An abrupt change in the longitudinal profile of a stream. Headcuts typically migrate upstream through time.||Coastal Engineering|
|Headland (head)||1. A comparatively high promontory with either a CLIFF or steep face extending out into a body of water, such as a sea or lake. An unnamed HEAD is usually called a headland.|
2. The section of RIP CURRENT which has widened out seaward of the BREAKERS, also called HEAD OF RIP. 3. Seaward end of BREAKWATER or dam.
|Headland beach||A narrow beach formed at the base of a cliffed headland.||Coastal Engineering|
|Headland||(NAVFAC DM-26.3/Shore Protection Manual/1984) A high, steep-faced promontory extending into the sea.||Coastal Engineering|
|Headwater level||The level of water in the reservoir.||Coastal Engineering|
|Headwater stream||Stream with a small drainage area (Ohio EPA defines as streams with drainage area < 10 mi2).||Coastal Engineering|
|Headwater||1. The source (or sources) and upper part of a stream, especially of a large stream or river, including the upper drainage basin; a stream from this source.|
2. The water upstream from a structure, as behind a dam.
|Heat Budget||The amount of heat energy required annually to raise the temperature of a water body from its winter minimum to its summer maximum.||Coastal Engineering|
|Heat Energy||An energy form proportional to and associated with molecular motion. Conduction, convection or radiation can transfer heat from one mass of matter to another.||Coastal Engineering|
|Heat of hydration||Heat generated by chemical reactions of cementitious materials with water, such as that evolved during the setting and hardening of portland cement||Coastal Engineering|
|Heat of Transformation||See Latent Heat.||Coastal Engineering|
|Heat of Vaporization||The heat required to convert a substance from the liquid to the gaseous state with no temperature change. This is also called the latent heat of vaporization.||Coastal Engineering|
|Heat Reflection||The return of radiant heat energy by a reflecting surface.||Coastal Engineering|
|Heat||Energy that is transferred from one body to another because of a difference in temperature.||Coastal Engineering|
|Heave compensator||See swell compensator.||Coastal Engineering|
|Heave||1. The vertical rise or fall of the waves or the sea.|
2. The translational movement of a craft parallel to its vertical axis.
3. The net transport of a floating body resulting from wave action.
|Heavy metals||(EM 1110-2-5026) Metals which have proven to be hazardous to living organisms ingesting them in sufficient quantities; generally, cadmium, nickel, lead, zinc, copper, mercury, chromium, and others.||Coastal Engineering|
|Heavy mineral||Mineral species with a specific gravity greater than a heavy liquid such as bromoform, used to separate heavies from lighter minerals. Usually with a specific gravity of around 2.9 or higher.||Coastal Engineering|
|Heel of dam||The location where the upstream face of the dam intersects the foundation.||Coastal Engineering|
|Henry's Law||States that at a given temperature the solubility of a gas is directly proportional to the pressure of the gas directly above the liquid.||Coastal Engineering|
|Herbivores||Plant eaters.||Coastal Engineering|
|Heterogeneous||A medium which consists of different (nonuniform) characteristics in different locations.||Coastal Engineering|
|Heterotrophic||A condition in which respiration by plants and animals exceeds oxygen production by plants. Primary energy sources are organic compounds.||Coastal Engineering|
|Heuristic model||Representation of a real system by a mathematical description based on reasoned, but unproven, argument.||Coastal Engineering|
|H-frame||Similar structural assembly to A-frame, but separated at top.||Coastal Engineering|
|High plasticity soil||A cohesive soil having a liquid limit water content of 50 percent or more. (See also liquid limit.)||Coastal Engineering|
This term, in municipal and international law, denotes the continuous body of salt water in the world that is navigable in its character and that lies outside territorial waters and maritime belts of the various countries.
|High tide, High water (HW)||The maximum elevation reached by each rising tide. See TIDE.||Coastal Engineering|
|High tide||The maximum elevation reached by each rising tide.||Coastal Engineering|
|High water (HW)||Maximum height reached by a rising tide. The height may be solely due to the periodic tidal forces or it may have superimposed upon it the effects of prevailing meteorological conditions. Nontechnically, also called the HIGH TIDE.||Coastal Engineering|
|High water inequality||See diurnal inequality.||Coastal Engineering|
|High water interval, hwi||See lunitidal interval.||Coastal Engineering|
|High water line|
In strictness, the intersection of the plane of mean high water with the shore. The shoreline delineated on the nautical charts of the National Ocean Service is an approximation of the high water line. For specific occurrences, the highest elevation on the shore reached during a storm or rising tide, including meteorological effects.
|High water mark||A reference mark on a structure or natural object, indicating the maximum stage of tide or flood.||Coastal Engineering|
|High water of ordinary spring tides (hwost)||A tidal datum appearing in some British publications, based on high water of ordinary spring tides.||Coastal Engineering|
|High water, full and change, hwf&c||See establishment of the port.||Coastal Engineering|
|High water, HW|
The maximum height reached by a rising tide. The height may be due solely to the periodic tidal forces or it may have superimposed upon it the effects of prevailing meteorological conditions. Use of the synonymous term, high tide, is discouraged.
|Higher high water, HHW||The highest of the high waters (or single high water) of any specified tidal day due to the declination effects of the Moon and Sun.||Coastal Engineering|
|Higher low water, HLW||The highest of the low waters of any specified tidal day due to the declination effects of the Moon and Sun.||Coastal Engineering|
|Highest astronomical tide (hat)||The highest level of water which can be predicted to occur under any combination of astronomical conditions. This level may not be reached every year.||Coastal Engineering|
|High-flow channel||A channel design employing a subchannel for normal and low flows and high-flow berms that are flooded on an infrequent basis. When the existing natural channel is used for the subchannel, excavation may take place from one or both sides, but the existing channel is disturbed as little as possible.||Coastal Engineering|
|Hindcasting||In wave prediction, the retrospective forecasting of waves using measured wind information.||Coastal Engineering|
|Hinterland||The region lying inland from the coast. Also the inland area served by a port.||Coastal Engineering|
|Hired labor||Process of accomplishing work through the use of Government plant and labor.||Coastal Engineering|
|Historic event analysis||Extreme analysis based on hindcasting typically ten events over a period of 100 years.||Coastal Engineering|
|Historic flows||The collection of recorded flow data for a stream during the period of time in which steam gages were in operation.||Coastal Engineering|
|Hofer valve||A relief valve, patented by a. L. Hofer, developed to eliminate suction-plugging caused by caving banks, sudden changes of material, or pockets of gas.||Coastal Engineering|
|Hog wires||Flexible wire rope stays which tie the h-frame of a hydraulic dredge to the dredge hull.||Coastal Engineering|
|Hoist control||The main controls in the lever room of a pipeline dredge which control the ladder, the spuds, and the swing wires.||Coastal Engineering|
|Holding power||The amount of force, carried through the anchor line, that an anchor will hold, without dragging.||Coastal Engineering|
|Holiday||An unintentional unsurveyed area within a given hydrographic survey project where the spacing between sounding lines or surveys exceeds the maximum allowable limits. (See also split.)||Coastal Engineering|
|Holocene||An epoch of the QUATERNARY period, from the end of the PLEISTOCENE, about 8,000 years ago, to the present time. Syn: Recent||Coastal Engineering|
|Holomictic||Typically mixes completely throughout the water column at least once a year.||Coastal Engineering|
|Home pontoon||See pontoon.||Coastal Engineering|
|Homogeneous fluid||A fluid which has uniform properties.||Coastal Engineering|
|Homogeneous||Uniform in structure or composition.||Coastal Engineering|
|Homopycnal flow||A condition in which the outflow jet from a river or coastal inlet and the water in the receiving basin are of the same density or are vertically mixed.||Coastal Engineering|
|Hook||A spit or narrow cape of sand or gravel which turns landward at the outer end; a RECURVED SPIT.||Coastal Engineering|
|Hopper capacity||The maximum volume of the hoppers of a hopper dredge.||Coastal Engineering|
Self-propelled floating plant which is capable of dredging material, storing it onboard, and transporting and placing the material at a specified disposal site. Often used to dredge inlets and then deposit the material along the open coast or offshore.
|Hopper overflow||Overfilling of hoppers to remove excess water and light density slurries to increase total hopper sediment concentration and thus increase the effective capacity of the dredge.||Coastal Engineering|
|Hopper pumpout||Ability to remove dredged material from hoppers with onboard pumps; may require adding water to hopper load.||Coastal Engineering|
|Horizontal closure method||Construction of a dam by dumping the materials from one or both banks, thus constricting the channel progressively laterally until the dam is closed. This method is also known as end dumping and point tipping||Coastal Engineering|
|Horizontal dilution of precision, hdop||Horizontal component of geometric dilution of precision.||Coastal Engineering|
|Horizontal positioning||Electronic surveying equipment with defined shore stations to provide accurate position of the dredging or placement activity. Available technology includes LORAN, Range/Azimuth, GPS, and microwave transmitters.||Coastal Engineering|
|Horizontal pressure gradient force||The horizontal component of the product of the specific volume and the rate of decrease in pressure with distance.||Coastal Engineering|
|Horticulture use||The beneficial uses of dredged material disposal sites as nursery or orchard sites, or of using dewatered dredged material as an ingredient in potting or plant bed soil mixtures. (See also beneficial uses.)||Coastal Engineering|
|Hose (dredge sleeves)||A flexible coupling which connects the suction pipe to the hull of the dredge.||Coastal Engineering|
|House||An enclosure built on top of the hull of a dredge to provide living quarters, work areas, etc. For the crew.||Coastal Engineering|
The HSPF Model, Hydrologic Simulation Program Fortran, is a U.S. EPA program for simulation of watershed hydrology and water quality for both conventional and toxic organic pollutants. The HSPF model uses information such as the time history of rainfall, temperature and solar radiation; land surface characteristics such as land use patterns; and land management practices to simulate the processes that occur in a watershed. The result of this simulation is a time history of the quantity and quality of runoff from an urban or agricultural watershed.
Flow rate, sediment load, and nutrient and pesticide concentrations are predicted. HSPF includes an internal database management system to process the large amounts of simulation input and output.
HSPF (Hydrological Simulation Program--Fortran) simulates for extended periods of time the hydrologic, and associated water quality, processes on pervious and impervious land surfaces and in streams and well-mixed impoundments.
HSPF uses continuous rainfall and other meteorologic records to compute streamflow hydrographs and pollutographs. HSPF simulates interception soil moisture, surface runoff, interflow, base flow, snowpack depth and water content, snowmelt, evapotranspiration, ground-water recharge, dissolved oxygen, biochemical oxygen demand (BOD), temperature, pesticides, conservatives, fecal coliforms, sediment detachment and transport, sediment routing by particle size, channel routing, reservoir routing, constituent routing, pH, ammonia, nitrite-nitrate, organic nitrogen, orthophosphate, organic phosphorus, phytoplankton, and zooplankton. Program can simulate one or many pervious or impervious unit areas discharging to one or many river reaches or reservoirs. Frequency-duration analysis can be done for any time series. Any time step from 1 minute to 1 day that divides equally into 1 day can be used. Any period from a few minutes to hundreds of years may be simulated. HSPF is generally used to assess the effects of land-use change, reservoir operations, point or nonpoint source treatment alternatives, flow diversions, etc. Programs, available separately, support data preprocessing and postprocessing for statistical and graphical analysis of data saved to the Watershed Data Management (WDM) file.
The model contains hundreds of process algorithms developed from theory, laboratory experiments, and empirical relations from instrumented watersheds.
|Hulk||1. Generally, an unrigged hull condemned as unfit for the risks of the sea and used as a floating depot or crane platform in a harbor or roadstead.|
2. Visible remnants of an abandoned wrecked/stranded vessel. (See also derelict; wreck.)
|Hull well||A recessed portion at the front of a pipeline dredge hull, that accommodates the base of the ladder.||Coastal Engineering|
|Hull||The hollow, lowermost portion of a vessel, floating partially immersed in the water and supporting the remainder of the vessel.||Coastal Engineering|
|Hundred year flood||More accurately referred to as a "one percent chance flood," a flood of a magnitude which, according to historical statistics, has one chance in 100 of occurring in any given year. (This does not necessarily mean that, once such a flood occurs, the location will not experience another for the next 99 years!) (USACE)||Coastal Engineering|
|Hurricane path or track||Line of movement (propagation) of the eye through an area.||Coastal Engineering|
|A continuous graph representing water level stages that would be recorded in a gage well located at a specified point of interest during the passage of a particular hurricane, assuming that effects of relatively short-period waves are eliminated from the record by damping features of the gage well. Unless specifically excluded and separately accounted for, hurricane surge hydrographs are assumed to include effects of astronomical tides, barometric pressure differences, and all other factors that influence water level stages within a properly designed gage well located at a specified point.||Coastal Engineering|
|Hurricane wind pattern or isovel pattern|
|An actual or graphical representation of near-surface wind velocities covering the entire area of a hurricane at a particular instant. Isovels are lines connecting points of simultaneous equal wind velocities, usually referenced 9 meters (30 feet) above the surface, in meters per second, knots, or meters per hour; wind directions at various points are indicated by arrows or deflection angles on the isovel charts. Isovel charts are usually prepared at each hour during a hurricane, but for each half hour during critical periods.||Coastal Engineering|
|Hurricane||An intense tropical cyclone in which winds tend to spiral inward toward a core of low pressure, with maximum surface wind velocities that equal or exceed 33.5 m/sec (75 mph or 65 knots) for several minutes or longer at some points. TROPICAL STORM is the term applied if maximum winds are less than 33.5 m/sec but greater than a whole gale (63 mph or 55 knots). Term is used in the Atlantic, Gulf of Mexico, and eastern Pacific.||Coastal Engineering|
|Hybrid model||Model combining at least two modeling techniques (e.g., physical and numerical) in a closely coupled fashion.||Coastal Engineering|
|Hydraulic conductance||A term which incorporates model geometry and hydraulic conductivity into a single value for simplification purposes. Controls rate of flow to or from a given model cell, river reach, etc.||Coastal Engineering|
|Hydraulic conductivity||The rate at which water of a specified density and kinematic viscosity can move through a permeable medium.||Coastal Engineering|
|Hydraulic current||A current in a channel caused by a difference in the surface elevation at the two ends. Such a current may be expected in a strait connecting two bodies of water in which the tides differ in time or range. The current in the East River, New York, connecting Long Island Sound and New York Harbor is an example.||Coastal Engineering|
|Hydraulic depth||The hydraulic depth is the ratio of cross-sectional area to top width at any given elevation.||Coastal Engineering|
|Hydraulic diffusivity||A property of an aquifer or confining bed defined as the ratio of the transmissivity to the storativity.||Coastal Engineering|
|Hydraulic dredge||Floating or (occasionally) truck-based plant which lifts the material through a suction pipe. It requires dilution water for material pickup, lift, and transportation. Often used to renourish beaches when material is pumped onto the shore from an offshore sand source.||Coastal Engineering|
|Hydraulic dredged material placement||Placement of slurry dredged material from hydraulic dredging. (See also hydraulic dredging.)||Coastal Engineering|
|Hydraulic gradient||The change in total head with a change in distance in a given direction which yields a maximum rate of decrease in head.||Coastal Engineering|
1. The difference in water height between upstream and downstream sides of a structure. (USACE)
2. A measure of energy or pressure, expressed in terms of the vertical height of a column of water that has the same pressure difference.
|Hydraulic jump||A sudden turbulent rise in water level, such as often occurs at the foot of a spillway when the velocity of rapidly flowing water is instantaneously slowed.||Coastal Engineering|
|Hydraulic model||A physical scale model of a river used for engineering studies.||Coastal Engineering|
|Hydraulic pipeline dredge||See dredge, hydraulic.||Coastal Engineering|
1. Equal to A/P, where A is cross-sectional area and P is wetted perimeter. Roughly comparable to average depth in wide, shallow streams.
2. Quotient of the wetted cross-sectional area and the wetted perimeter.
|Hydraulically equivalent grains||Sedimentary particles that settle at the same rate under the same conditions.||Coastal Engineering|
|Hydraulics||The study and computation of the characteristics, e.g. depth (water surface elevation), velocity, and slope of water flowing in a stream or river.||Coastal Engineering|
|Hydric soils||Soils that are ponded, flooded, or saturated long enough during the growing season to develop anaerobic conditions.||Coastal Engineering|
An organic compound containing only carbon and hydrogen.
|Hydrodynamic modeling||A model of fluids (water) in motion.||Coastal Engineering|
|Hydrodynamic||Relates to the specific scientific principles that deal with the motion of fluids and the forces acting on solid bodies immersed in fluids, and in motion relative to them.||Coastal Engineering|
|Hydrogen Bond||A type of chemical bond caused by electromagnetic forces, occurring when the positive pole of one molecule (e.g., water) is attracted to and forms a bond with the negative pole of another molecule (e.g., another water molecule).||Coastal Engineering|
|Hydrogen Ion||An individual atom of hydrogen which is not attached to a molecule and therefore has a positive (+) charge.||Coastal Engineering|
|Hydrogen||Colorless, odorless and tasteless gas; combines with oxygen to form water.||Coastal Engineering|
|Hydrogeology||The branch of geology dealing with groundwater.||Coastal Engineering|
A graph showing, for a given point on a stream or channel, the discharge, water surface elevation, stage, velocity, available power, or other property of water with respect to time.
|Hydrographer||1. One who studies and practices the science of hydrography.|
2. The person responsible for the acquisition of hydrographic data for a hydrographic survey.
|Hydrographic datum||A datum used for referencing depths of water or the heights of predicted tides. (See also chart datum; datum.)||Coastal Engineering|
|Hydrographic pressure||The pressure exerted by water at any given point in a body of water at rest.||Coastal Engineering|
|Hydrographic survey examination||Effective October 1, 1982, consequent to a formal policy establishing Marine Center responsibility for hydrographic survey quality and final approval, the Headquarters quality control inspection of all hydrographic surveys was discontinued. It is inten||Coastal Engineering|
|Hydrographic survey||A survey having for its principal purpose the determination of data relating to a body of water for the purpose of promoting safe navigation.|
A hydrographic survey may consist of the determination of one or several of the following classes of data: depth of water; configuration and nature of the bottom; velocity of currents; heights and times of tides and water stages; location of aids and dangers for navigation and survey purposes; configuration of marginal land areas; and determination of magnetic declination and anomalies for navigating by magnetic compass.
Information on geographic names and harbor facilities is also often documented. (See also Section 4.1.2 of the Hydrographic Manual.)
|Hydrography||1. The description and study of seas, lakes, rivers and other waters.|
2. The science of locating aids and dangers to navigation.
3. The description of physical properties of the waters of a region.
|Hydrologic cycle||The circulation of water from the oceans through the atmosphere to the land and ultimately back to the ocean.||Coastal Engineering|
|Hydrologic equation||An expression of the law of mass conservation for purposes of water budgets. It may be stated as inflow equals outflow plus or minus changes in storage.||Coastal Engineering|
|Hydrology||The study of the properties, distribution, and circulation of water on the surface of the land in the soil and in the atmosphere.||Coastal Engineering|
|Hydrostatic Pressure||Pressure exerted in a column of water.||Coastal Engineering|
|Hypolimnetic Oxygen Depletion||A condition where the dissolved oxygen in the bottom layer (hypolimnion) of a water body is gradually consumed through respiration and decomposition faster than it can be replaced over the course of the summer. A similar phenomenon may occur in the winter under ice cover. The rate at which O2 is depeleted is a measure of the productivity of the system.||Coastal Engineering|
|Hypolimnion||The bottom, and most dense layer of a stratified lake. It is typically the coldest layer in the summer and warmest in the winter. It is isolated from wind mixing and typically too dark for much plant photosynthesis to occur.||Coastal Engineering|
|Hypopycnal flow||Outflow from a river or coastal inlet in which a wedge of less dense water flows over the denser sea water.||Coastal Engineering|
|Hyporheic zone||Zone of substrate in a stream bottom extending 1 to 2 meters below the surface of the stream bed.||Coastal Engineering|
|Hypothetical hurricane (hypohurricane)|
A representation of a hurricane, with specified characteristics, that is assumed to occur in a particular study area, following a specified path and timing sequence. TRANSPOSED--A hypohurricane based on the storm transposition principle, assumed to have wind patterns and other characteristics basically comparable to a specified hurricane of record, but transposed to follow a new path to serve as a basis for computing a hurricane surge hydrograph that would be expected at a selected point. Moderate adjustments in timing or rate of forward movement may also be made, if these are compatible with meteorological considerations and study objectives.
HYPOHURRICANE BASED ON GENERALIZED PARAMETERS--Hypohurricane estimates based on various logical combinations of hurricane characteristics used in estimating hurricane surge magnitudes corresponding to a range of probabilities and potentialities. The standard project hurricane is most commonly used for this purpose, but estimates corresponding to more severe or less severe assumptions are important in some project investigations. STANDARD PROJECT HURRICANE (SPH)--A hypothetical hurricane intended to represent the most severe combination of hurricane parameters that is reasonably characteristic of a specified region, excluding extremely rare combinations. It is further assumed that the SPH would approach a given project site from such direction, and at such rate of movement, to produce the highest hurricane surge hydrograph, considering pertinent hydraulic characteristics of the area. Based on this concept, and on extensive meteorological studies and probability analyses, a tabulation of "Standard Project Hurricane Index Characteristics" mutually agreed upon by representatives of the U. S. Weather Service and the Corps of Engineers, is available. PROBABLE MAXIMUM HURRICANE--A hypohurricane that might result from the most severe combination of hurricane parameters that is considered reasonably possible in the region involved, if the hurricane should approach the point under study along a critical path and at optimum rate of movement. This estimate is substantially more severe than the SPH criteria. DESIGN HURRICANE--A representation of a hurricane with specified characteristics that would produce hurricane surge hydrographs and coincident wave effects at various key locations along a proposed project alignment. It governs the project design after economics and other factors have been duly considered. The design hurricane may be more or less severe than the SPH, depending on economics, risk, and local considerations.
back to top
|Ice Age||A loosely-used synonym of glacial epoch, or time of extensive glacial activity; specifically of the latest period of widespread continental glaciers, the PLEISTOCENE Epoch.||Coastal Engineering|
|Ice Front||The floating vertical cliff forming the seaward edge of an ICE SHELF or other glacier that enters the sea.||Coastal Engineering|
|Ice Model||Model in which formation of ice, ice conditions, or ice forces are simulated.||Coastal Engineering|
A extensive sheet of ice which is attached to the land along one side but most of which is afloat and bounded on the seaward side by a steep cliff (ICE FRONT) rising 2 tp 50+ m above sea level. Common along polar coasts (Antarctica, Greenland), and generally of great breadth and sometimes extending tens or hundreds of km seaward from the continental coastline.
|Ice-out||Date when lake thaws.||Coastal Engineering|
|Idler Barge||See barge.||Coastal Engineering|
|Impact Costs||Those costs which are variously described by a contractor as indirect or "ripple" and claimed to be sufficiently related to direct costs as to be recoverable. Often viewed by the government as being consequential.||Coastal Engineering|
|Impairment||Impact that damages the biological integrity of a water body such that attainment of the designated use is prevented.||Coastal Engineering|
|Impedance||Mathematically, the product of the seismic wave velocity through a material and its density. Used to provide continuous information pertaining to estimates of density and material type between borings.||Coastal Engineering|
1. The rotation internal part of the dredge pump that creates the suction that brings the mixture of water and dredged materials into the pump and pushes them through the discharge pipe to the disposal facility.
2. A device which creates a low pressure region as it moves material through the discharge and other material is sucked in, or pushed in, by atmospheric or atmospheric and hydrostatic pressure (Hydrostatic results from a submerged pump).
3. A rotor or rotating device with from 2 to 5 vanes inside a centrifugal pump that imparts momentum to the fluid or slurry.
|Impermeable Groin||A GROIN constructed such that sand cannot pass through the structure (but sand may still move over or around it).||Coastal Engineering|
|Impervious Surface||Surfaces, such as roads, parking lots and roofs, whose properties prevent the infiltration of water and increase the amount of storm water runoff in a watershed.||Coastal Engineering|
|Impingement||When organisms are drawn against the intake trash rack or screen and held by the force of the water current.||Coastal Engineering|
Scheme in which the governing equations of a numerical model are arranged to obtain solutions for the dependent variables simultaneously at all grid points corresponding to any one time. The computed values depend not only on known values at a previous time but also on the other unknown neighboring values at the surrounding grid points at the time being calculated. (Compare with EXPLICIT SCHEME).
|Impoundment Basin||See sediment basin.||Coastal Engineering|
|Impoundment||Body of water formed by collecting water, as at a dam.||Coastal Engineering|
|In Place Density||See in situ density.||Coastal Engineering|
|In Situ Density||The bulk density of soil or rock sediments in situ.||Coastal Engineering|
|In Situ||Applied to a rock or soil when occurring in the situation in which it is naturally formed or deposited.||Coastal Engineering|
|Incident Wave||Wave moving landward.||Coastal Engineering|
|Incised Channel||A stream that, through degradation, has cut its channel into the bed of the stream valley.||Coastal Engineering|
|Incision||See entrenchment.||Coastal Engineering|
|Incremental Placement||The placement of dredged material in a placement site in small lifts over an extended period of time. The purpose of the procedure is to increase the natural drying and consolidation process of the dredged material to increase the long-term storage volume of a confined disposal facility. (See also lifts.)||Coastal Engineering|
|Indefinite Delivery Type, Idt, Contract||Form of service contract for procuring recurring services, such as hydrographic surveys.||Coastal Engineering|
|Indian Spring Low Water||The approximate level of the mean of lower low waters at spring tides, used principally in the Indian Ocean and along the east coast of Asia. Also INDIAN TIDE PLANE.||Coastal Engineering|
|Indian Tide Plane||The datum of INDIAN SPRING LOW WATER.||Coastal Engineering|
|Industrial/Commercial Use||The beneficial uses of dredged material for port, harbor, airport, building, or other industrial and commercial enterprise uses. (See also beneficial uses.)||Coastal Engineering|
|Inequality||A systematic departure from the mean value of a tidal quantity. (See also diurnal inequality; parallax inequality; phase inequality.||Coastal Engineering|
|The maximum rate at which infiltration can occur under specific conditions of soil moisture. For a given soil, the infiltration capacity is a function of the water content.||Coastal Engineering|
|Infiltration||The flow of water downward from the land surface into and through the upper soil layers.||Coastal Engineering|
|Inflow||Water flowing into a lake.||Coastal Engineering|
|Infragravity Wave||Long waves with periods of 30 seconds to several minutes.||Coastal Engineering|
|Initial Conditions||The values of water levels, velocities, concentrations, etc., that are specified everywhere in the grid or mesh at the beginning of a model run. For iterative solutions, the initial conditions represent the first estimate of the variables the model is trying to compute.||Coastal Engineering|
|That dispersion or diffusion of liquid, suspended particulate, and solid phases of dredged material that occurs after dumping. Water quality criteria or standards, as appropriate, shall not be exceeded beyond the boundaries of the disposal site after initial mixing.||Coastal Engineering|
|Inland Waters||Waters landward of the baseline (COASTLINE) from which the marginal seas are measured and over which complete sovereignty is exercised. Also known as "internal waters."||Coastal Engineering|
|Inlet Gorge||Generally, the deepest region of an inlet channel.||Coastal Engineering|
|Inlet||1. A short, narrow waterway connecting a bay, lagoon, or similar body of water with a large parent body of water.|
2. An arm of the sea (or other body of water), that is long compared to its width, and may extend a considerable distance inland.
3. A connecting passage between two bodies of water. Typically refers to tidal openings in barrier islands, but can also be applied to river mouths in tidal and non-tidal environments.
|Inorganic||Substances of mineral, not carbon origin.||Coastal Engineering|
|Process by which the amount of work accomplished (i.e., the amount of material excavated or placed) is determined by measuring the in-place conditions, utilizing before- and after-dredge surveys. The surveys may be either topographic or hydrographic.||Coastal Engineering|
|Inset||A small survey area which may or may not fall within the normal limits of a survey sheet and which is plotted within the limits of the sheet (at either the same or a differing scale) to obviate the need for a separate sheet. When a small harbor, anchorage, or other area is surveyed or platted at a scale larger than the remainder of inshore coastal waters, it may frequently be included as an inset on the sheet that includes the area. A unique set of projection parameters are derived for an inset and the plotted display is enclosed within a border and contains a legend and graticule.|
(See also subplan; panel.)
|Inshore (zone)||In beach terminology, the zone of variable width extending from the LOW WATER LINE through the BREAKER ZONE. Also SHOREFACE.||Coastal Engineering|
|Inshore Current||Any current in or landward of the BREAKER ZONE.||Coastal Engineering|
|Inspection of Site (Site Investigation)|
|The investigation of the site by the contractor, required by the contract clauses of the contract, to acquaint and satisfy himself as to the conditions affecting the work.||Coastal Engineering|
|Inspection, In Quality Assurance||See quality inspection.||Coastal Engineering|
|Inspector||That person assigned by the contracting officer to check materials of construction, methods of construction, and workmanship for contract compliance.||Coastal Engineering|
|Instantaneous Modulus of Elasticity||The modulus of elasticity of concrete that occurs immediately after loading||Coastal Engineering|
|A suspended-sediment sampler that instantaneously traps a sample of the water-sediment mixture in a stream at a desired depth.||Coastal Engineering|
Flow Incremental Methodology (IFIM)
|A five phase management and negotiation tool used for water allocation. The five phases are problem identification, study planning, study implementation, alternatives analysis, and problem resolution. Analysis is based on stream channel characteristics, water column dynamics, the historical flow record and target species habitat requirements or management goals.||Coastal Engineering|
|Instream Flow||The amount of water in a stream that is required to sustain downstream uses within the channel, such as aquatic habitat, aquatic life, recreation, or wastewater assimilation.||Coastal Engineering|
|Instrumentation||Devices installed on and embedded within a dam to monitor the structural behavior during and after construction of the dam.||Coastal Engineering|
|Insular Shelf||The zone surrounding an island extending from the LOW WATER LINE to the depth (usually about 183 m; 100 fathoms) where there is a marked or rather steep descent toward the great depths.||Coastal Engineering|
|Intake Structure||The structure in the forebay that is the entrance to any water transporting facility such as a conduit or tunnel.||Coastal Engineering|
|Interbasin transfer||The physical transfer of water from one river basin to another.||Coastal Engineering|
|Interface||A line or place separating two different types of materials.||Coastal Engineering|
|Interflow||The lateral movement of water in the unsaturated zone during and immediately after a precipitation event. The water moving as interflow discharges directly into a stream or lake.||Coastal Engineering|
|Interim (contract) Hydrographic Survey||A hydrographic survey performed during construction to monitor progress or placement, often for interim progress payment purposes.||Coastal Engineering|
|Interior Collection Pond||See Collection pond; sometimes called interior drainage pond.||Coastal Engineering|
|Intermediate Completion Dates||Dates established in a contract for completion or occupancy of designated facilities or features of a facility before the date for completion of all work under the contract. Established from BOD.||Coastal Engineering|
|Intermediate Principal Stress||The principal stress whose value is neither the largest nor the smallest (with regard to sign) of the three.||Coastal Engineering|
|Intermittent Dredging||The shutting on and off of a dredging operation on a scheduled basis (i.e., one hour on/one hour off) to allow settling to occur and effluent water to move at a slower rate.||Coastal Engineering|
|Intermittent Stream||A stream that ceases to flow seasonally or occasionally because bed seepage and evaporation exceed the supply of water.||Coastal Engineering|
|Internal Friction||See angle of internal friction.||Coastal Engineering|
|Internal Tide||A tidal wave propagating along a sharp density discontinuity, such as at a thermocline, or in an area of gradually changing density (vertically).||Coastal Engineering|
|Internal Waves||Waves that occur within a fluid whose density changes with depth, either abruptly at a sharp surface of discontinuity (an interface), or gradually. Their amplitude is greatest at the density discontinuity or, in the case of a gradual density change, somewhere in the interior of the fluid and not at the free upper surface where the surface waves have their maximum amplitude.||Coastal Engineering|
|International Great Lakes Datum (1955), igld (1955)||The datum established as a low water reference plane for the Great Lakes and certain connecting waters. It is based on the mean water level at Father Point (Pointe-au-Pere), Quebec, on the Gulf of St. Lawrence over the period 1941 through 1956, from which dynamic elevations throughout the Great Lakes region are measured. Elevations presently based on IGLD represent elevations as of the year 1955. (See also low water datum.)||Coastal Engineering|
|International Hydrographic Organization (formerly bureau)||An institution consisting of representatives of a number of nations organized for the purpose of coordinating the hydrographic work of the participating governments. It had its origin in the International Hydrographic Conference in London in 1919. It has permanent headquarters in the Principality of Monaco and is supported by funds provided by the member nations. Its principal publications include the Hydrographic Review and special publications on technical subjects.||Coastal Engineering|
|International Low Water||A hydrographic datum originally suggested for international use at the International Hydrographic Conference in London in 1919, and later discussed at the Monaco Conference in 1926. The proposed datum, which has not yet been generally adopted, was to be "a plane so low that the tide will but seldom fall below it." This datum was the subject of the International Hydrographic Bureau's Special Publication No. 5 (March 1925) and No.10 (January 1926), reproduced in the Hydrographic Review for May 1925 and July 1926.||Coastal Engineering|
|Interpolation||Estimation of an intermediate value of one variable (dependent) as a function of a second variable (independent) when values of the dependent variable corresponding to several discrete values of the independent variable are known.||Coastal Engineering|
|Interstitial Flow||Water flow through bed (i.e., riffle) and bar materials.||Coastal Engineering|
|Intertidal Zone||That land area between mean low water and mean high water that is inundated periodically by tides.||Coastal Engineering|
|Intertidal||The zone between the high and low water tides.||Coastal Engineering|
|Interval||See lunitidal interval and lunicurrent interval.||Coastal Engineering|
|Intra-port||Movement within a port.||Coastal Engineering|
|Invert||The bed of a channel or culvert.||Coastal Engineering|
|Investigation Survey||See reconnaissance survey.||Coastal Engineering|
|Ion||An electrically charged particle.||Coastal Engineering|
|Ionosphere||The band of charged particles 80 to 120 miles above the earth's surface.||Coastal Engineering|
|Ionospheric Refraction||The change in the propagation speed of a signal as it passes through the ionosphere.||Coastal Engineering|
|Irminger Current||North Atlantic Ocean current setting westward off the southwest coast of Iceland.||Coastal Engineering|
|Irregular Waves||Waves with random wave periods (and in practice, also heights), which are typical for natural wind-induced waves.||Coastal Engineering|
|Irrotational Wave||A wave with fluid particles that do not revolve around an axis through their centers, although the particles themselves may travel in circular or nearly circular orbits. Irrotational waves may be PROGRESSIVE, STANDING, OSCILLATORY, or TRANSLATORY. For example, the Airy, Stokes, cnoidal, and solitary wave theories describe irrotational waves. Compare TROCHOIDAL WAVE.||Coastal Engineering|
|Isanostere||An isopleth of either specific volume anomaly or thermosteric anomaly.||Coastal Engineering|
|Island||See dredged material island.||Coastal Engineering|
|Isobar||An isopleth of pressure.||Coastal Engineering|
|Isobaric Surface||A surface of constant or uniform pressure.||Coastal Engineering|
|Isobath||A contour line connecting points of equal water depths on a CHART.||Coastal Engineering|
|Isohaline||An isopleth of salinity. Constant or uniform in salinity.||Coastal Engineering|
|To collect a water-sediment mixture at the velocity of the approaching flow ; that is, the velocity of the mixture experiences no acceleration or deceleration as it leaves the ambient flow and enters the sampler intake.||Coastal Engineering|
|Isopach||A line drawn on a map through points of equal true thickness of a designated stratigraphic unit or group of stratigraphic units.||Coastal Engineering|
|Isopachyte||Line connecting points on the seabed with an equal depth of sediment.||Coastal Engineering|
|Isopleth||A line of constant or uniform value of a given quantity. (See also isanostere; isobar; isohaline; isopyenic; isotherm.)||Coastal Engineering|
|Isostatic Adjustment||The process by which the crust of the earth attains gravitational equilibrium with respect to superimposed forces such as gravity. An example is the depression of land masses caused by the over-burden of continental glaciers.||Coastal Engineering|
|Isotherm||An isopleth of temperature.||Coastal Engineering|
|Isothermal||Constant in temperature.||Coastal Engineering|
|Isotropic||Having identical properties in all directions.||Coastal Engineering|
|Isotropy||The condition in which hydraulic properties of the aquifer are equal in all directions.||Coastal Engineering|
|Isovel Pattern||See hurricane wind pattern.||Coastal Engineering|
|Isthmus||A narrow strip of land, bordered on both sides by water, that connects two larger bodies of land.||Coastal Engineering|
|J1||Smaller lunar elliptic diurnal constituent. This constituent, with M1, modulates the amplitudes of the declinational K1 for the effect of the Moon's elliptical orbit.||Coastal Engineering|
|Jacob straight-line method||A graphical method using semilogarithmic paper and the Theis equation for evaluating the results of a pump test.||Coastal Engineering|
|JALBTCX||Joint Airborne Lidar Bathymetry Technical Center of Expertise||Coastal Engineering|
|Jet flow||A type of flow characterized by water moving in plunging, jet-like surges, produced where a turbulent current enters a body of standing water.||Coastal Engineering|
|Jet||To place (a pile, slab, or pipe) in the ground by means of a jet of water acting at the lower end.||Coastal Engineering|
|Jetting||A method of placing piles by forcing water around and under a pile to displace and lubricate the surrounding soil, allowing the pile to sink to the desired position.||Coastal Engineering|
1. (U. S. usage) On open seacoasts, a structure extending into a body of water, and designed to prevent shoaling of a channel by littoral materials, and to direct and confine the stream or tidal flow. Jetties are built at the mouth of a river or tidal inlet to help deepen and stabilize a channel.
2. (British usage) Jetty is synonymous with "wharf" or "pier".
3. A shore-perpendicular structure built to stabilize an inlet and prevent the inlet channel from filling with sediment.
|Job overhead||See cost.||Coastal Engineering|
|Joint probability density||Function specifying the joint distribution of two (or more) variables.||Coastal Engineering|
|Joint probability||The probability of two (or more) things occurring together.||Coastal Engineering|
|Joint return period||Average period of time between occurrences of a given joint probability event.||Coastal Engineering|
An ad hoc agreement between two or more firms for the specific purpose of performing one contract or job. It is legally constituted to create a resulting firm that will meet statutory requirements for bidding federal contracts.
|Jointing||The tendency of rocks to develop parallel sets of fractures without obvious external movement like faulting.||Coastal Engineering|
A law to protect U.S. domestic oceanborne commerce and U.S.- flag vessels engaged in coastwise trade by prohibiting the transportation of cargoes in foreign-flag vessels between points in the United States, either directly or via a foreign port, in any other vessel than a vessel built in and documented under the laws of the United States, and owned by persons who are U.S. citizens.
|JONSWAP spectrum||Wave spectrum typical of growing deep water waves developed from field experiments and measurements of waves and wave spectra in the Joint North Sea Wave Peoject.||Coastal Engineering|
|Judgement sampling||In quality assurance, the traditional engineering sampling method, based on a deterministic (non-statistical) attitude toward variability and the concept of the representative sample.||Coastal Engineering|
|Julian calendar||A calendar introduced by Julius Caesar in the year 45 B.C., and slightly modified by Augustus a few years later. This calendar provided that the common year should consist of 365 days and that every fourth year, now known as a bissextile or leap year, should contain 366 days, making the average length of the year 365.25 days. It differs from the modern or Gregorian calendar in having every fourth year a leap year, while in the modern calendar century years not divisible by 400 are common years. (See also Gregorian calendar.)||Coastal Engineering|
Technique for the identification of successive days of the year when monthly notation is not desired. This is especially applicable in computer data processing and acquisition where library indexing is necessary.
|Julian day||The consecutive number of each day commencing January 1, 4713 BC. The Julian day number denotes the number of days elapsed since noon on the initial day of the epoch; e.g., noon on May 17, 1985, marks the beginning of Julian day 2,446,203. For NOS purposes, the sequential 3-digit day number of the year should be referred to as the "day-of-the-year" rather than "Julian day".||Coastal Engineering|
|Jumping on a line||(Huston. Hydraulic Dredging Principles...) Effort to free a stranded vessel with a sudden pull on the towline.||Coastal Engineering|
|Junction||A place of meeting or joining. in hydro surveying, the joining of two or more adjacent/adjoining survey sheets.||Coastal Engineering|
|Jury rig||(Huston. Hydraulic Dredging Principles...) Any makeshift device or apparatus rigged as a substitute for regular gear. Also the act of setting up a jury rig.||Coastal Engineering|
back to top
|K1||Lunisolar diurnal constituent. This constituent, with 01, expresses the effect of the Moon's declination. They account for diurnal inequality and, at extremes, diurnal tides. With P1 it expresses the effect of the Sun's declination. Speed = T + h = 15.0410686 deg per solar hour.||Coastal Engineering|
|K2||Lunisolar semidiurnal constituent. This constituent modulates the amplitude and frequency of M2 and S2 for the declinational effect of the Moon and Sun, respectively. Speed = 2T + 2h = 30.0821373 deg per solar hour.||Coastal Engineering|
Name of Greek letter used as the symbol for a constituent phase lag or epoch when referred to the local equilibrium argument and frequently taken to mean the same as local epoch. (See also epoch (1))
Synonym : Epoch
|Karst||The type of geologic terrain underlain by carbonate rocks where significant solution of the rock has occurred due to the flowing groundwater. Karst topography is frequently characterized by sinkholes, caves, and underground drainage.||Coastal Engineering|
|Katabatic wind||Wind caused by cold air flowing down slopes due to gravitational acceleration.||Coastal Engineering|
|Keeper||See spud well.||Coastal Engineering|
|Key||A cay, esp. one of the low, insular banks of sand, coral, and limestone off the southern coast of Florida.||Coastal Engineering|
|Kinematic positioning||(EM 1110-2-1003) Dynamic positioning.||Coastal Engineering|
|Kinematic similarity||Similarity of motion.||Coastal Engineering|
|Kinematic viscosity||The dynamic viscosity divided by the fluid density.||Coastal Engineering|
|Kinetic energy (of waves)||In a progressive oscillatory wave, a summation of the energy of motion of the particles within the wave.||Coastal Engineering|
|Knickpoint||A bedrock outcrop that creates an abrupt change in the longitudinal profile of a stream and controls the streambed elevation. (Same as Headcut)||Coastal Engineering|
|Knoll||A submerged elevation of rounded shape rising less than 1000 meters from the ocean floor and of limited extent across the summit. Compare SEAMOUNT.||Coastal Engineering|
1. A nautical unit of speed defined as 1 international nautical mile per hour. It was previously defined as 1 nautical mile per hour, but this led to confusion, because the American and British nautical miles differ by 1.184 m. The knot is equal to 1.852 km/h.
2. A division of the log line, by which the ship's speed is measured. The name is derived from the knots in the log line.
|Knuckle joint||A slip sleeve component used to transmit power from an engine on the hull of the dredge to a cutter shaft mounted on the ladder.||Coastal Engineering|
|Kuroshio system||The current system composed of the Kuroshio, Tsushima Current, Kuroshio Extension, and North Pacific Current.||Coastal Engineering|
|Kuroshio||A North Pacific Ocean current setting northeastward off the east coast of Taiwan and Japan from Taiwan to about latitude 35? north.||Coastal Engineering|
1. The quality, state, or condition of peakedness or flatness of the graphic representation of a statistical distribution.
2. A measure of the peakedness of a frequency distribution (e.g., a measure of concentration of sediment particles about the median diameter).
back to top
|L2||Smaller lunar elliptic semidiurnal constituent. This constituent, with N2, modulates the amplitude and frequency of M2 for the effect of variation in the Moon's orbital speed due to its elliptical orbit. Speed = 2T - s + 2h - p = 29.5284789 deg per solar hour.||Coastal Engineering|
|Labrador current||A North Atlantic Ocean current setting southeastward along the east coasts of Baffin Island, Labrador, and Newfoundland.||Coastal Engineering|
|Ladder bucket||Buckets which carry material during the operation of a ladder dredge.||Coastal Engineering|
|Ladder inclination||Vertical angle of depression of the ladder from the horizontal. Usually less than 50 degrees.||Coastal Engineering|
|Ladder pump||A dredge pump which is located on the dredge ladder or drag arm. The pump is submerged during dredging operations.||Coastal Engineering|
|Ladder swell compensator||See compensated cutterhead dredge.||Coastal Engineering|
|Ladder trunnions||A basic pin and housing arrangement on either side of the rearward portion of the ladder where they make connection with the hull which act as pivots for the ladder's up-and-down motion, absorbing all the live loading and shock of dredging.||Coastal Engineering|
|Ladder||See dredge ladder.||Coastal Engineering|
|Ladderhead bearing||A bearing especially made for the cutterhead of a dredge which is made of rubber vulcanized or set inside a metal housing & which is lubricated by pumping water into them at high pressure. Two principal types are the B.F. Goodrich "cutlass" and the Johnson "stave".||Coastal Engineering|
|Lagging of tide||The periodic retardation in the time of occurrence of high and low water due to changes in the relative positions of the Moon and Sun.||Coastal Engineering|
1. A shallow body of water, like a pond or sound, partly or completely separated from the sea by a BARRIER ISLAND or REEF. Sometimes connected to the sea via an INLET.
2. Open water between a coastal barrier and the mainland. Also water bodies behind coral reefs and enclosed by atolls.
|Lagrangian measurement||Observation of a current with a device flowing with the current.||Coastal Engineering|
|Lahar||A landslide or mudflow of pyroclastic material that flows down the flanks of a volcano, often at great speed and with destructive violence.||Coastal Engineering|
|Lake Profile||A graph of a lake variable per depth; where the depth is on the z-axis and the variable is on the x-axis. Depth is the independent variable and the x-axis is the dependent variable.||Coastal Engineering|
|Lambda2||Smaller lunar evectional constituent. This constituent, with v2, µ2, and (S2), modulates the amplitude and frequency of M2 for the effects of variation in solar attraction of the Moon. This attraction results in a slight pear-shaped lunar ellipse and a difference in lunar orbital speed between motion toward and away from the Sun. Although (S2) has the same speed as S2, its amplitude is extremely small. Speed = 2T - s + p = 29.4556253 deg per solar hour.||Coastal Engineering|
|Laminae||(or lamina) The thinnest recognizable layer in a sediment or sedimentary rock.||Coastal Engineering|
|Laminar flow||1. Slow, smooth flow, with each drop of water traveling a smooth path parallel to its neighboring drops. Laminar flow is characteristic of low velocities, and particles of sediment in the flow zones are moved by rolling or SALTATION.|
2. Type of flow in which the fluid particles follow paths that are smooth, straight, and parallel to the channel walls. In laminar flow, the viscosity of the fluid damps out turbulent motion.
|LaMotte Water Quality Testing Kits||The LaMotte Company (website: http://www.lamotte.com/) is one of a number of companies that market a variety of test kits and field and lab instruments for water quality testing. Additional companies commonly cited are Hach and CHEMetrics, and there are probably numerous others accessible to the reader through various educational resources or scientific lab products catalogues. Water on the Web does not endorse any particular company’s products. Some test kits have been "approved" by state or federal agencies for certain types of tests in specific types of water or wastewater.||Coastal Engineering|
|Land breeze||A light wind blowing from the land to the sea, caused by unequal cooling of land and water masses.||Coastal Engineering|
|Land Use and Land Cover (LULC)|
(USGS) Land Use and Land Cover (LULC) data consists of historical land use and land cover classification data that was based primarily on the manual interpretation of 1970's and 1980's aerial photography. Secondary sources included land use maps and surveys. There are 21 possible categories of cover type. Along with the LULC files, associated maps are included which provide additional information on political units, hydrologic units, census county subdivisions, and Federal and State land ownership.
|Landing pontoon||See pontoon||Coastal Engineering|
(Huston. Hydraulic Dredging Principles...) Point of transition from a floating line to the shoreline. Also where crews and materials are picked up by the tender.
|Landlocked||Enclosed, or nearly enclosed, by land--thus protected from the sea, as a bay or a harbor.||Coastal Engineering|
|Landmark||A conspicuous object, natural or artificial, located near or on land, which aids in fixing the position of an observer.||Coastal Engineering|
|Landscape||All the natural geographical features, such as fields, hills, forests, and water that distinguish one part of the earth's surface from another part. These characteristics are a result not only of natural forces but of human use of the land as well.||Coastal Engineering|
|Land-sea breeze||The combination of a land breeze and a sea breeze as a diurnal phenomenon.||Coastal Engineering|
|landslide (slide)||(ASTM D 653) The failure of a sloped bank of soil or rock in which the movement of the mass takes place along a surface of sliding.||Coastal Engineering|
|Landuse||The primary or primary and secondary uses of land, such as cropland, woodland, pastureland, forest, water (lakes, wetlands, streams), etc. The description of a particular landuse should convey the dominant character of a geographic area and establish the dominant types of human activities which are prevalent in each region.||Coastal Engineering|
|Lantern ring||The portion of the stuffing box which provides a seal around the impeller shaft where it enters the pump casing. This prevents outside air pressure from getting in when the pump is acting on a suction lift. Service water is applied at a greater pressure to the lantern ring than the head created by the pump, creating the seal.||Coastal Engineering|
|Laplace equation||The partial differential equation governing steady-state flow in a homogeneous, isotropic aquifer||Coastal Engineering|
|Large navigation buoy, inb||||Coastal Engineering|
|large navigation buoy, lnb||A 40-foot diameter, automated disc-shaped buoy used to replace lightships. Most LNBs are used in conjunction with major Traffic Separation Schemes. All LNBs are equipped with Emergency lights.||Coastal Engineering|
|Latent defect||A defect in the work not in accord with the specification which could not be observed by reasonable inspection.||Coastal Engineering|
|Latent detect||||Coastal Engineering|
|Latent Heat (Energy)||The amount of heat (energy) released from or absorbed by a substance when it undergoes a change of state; also known as Heat of Transformation.||Coastal Engineering|
|Launch||Small attendant vessel used by a dredge to jerry supplies/personnel.||Coastal Engineering|
|Lava||Molten rock (and gasses with the rock) that have erupted onto the earth's surface.||Coastal Engineering|
|Lay of wire rope||The structure of wire rope characterized by the degree and direction of the twist and the angles formed by the strands.||Coastal Engineering|
|Le Chatelier's Principle||A principle of equilibrium; states that in a balanced equilibrium, if one or more factors changes, the system will readjust to reach equilibrium.||Coastal Engineering|
|Leach||To remove soluble or other constituents from a medium by the action of a percolating liquid, as in leaching salts from the soil by the application of water.||Coastal Engineering|
|Leachate collection system|||||
|Leaky confining layer|||||
|Leased dredge construction contract|||||
|Ledge rock||bedrock (ledge).||Coastal Engineering|
|Ledge||A rocky formation forming a ridge or REEF, especially one underwater or near shore||Coastal Engineering|
1. Shelter, or the part or side sheltered or turned away from the wind or waves.
2. (Chiefly nautical) The quarter or region toward which the wind blows.
|Leeward||The direction toward which the wind is blowing; the direction toward which waves are traveling.||Coastal Engineering|
|Left-right (helmsman's) track indicator||(EM 1110-2-1003) A digital or analog device on a survey boat or dredge which guides the helmsman in steering a prescribed channel alignment or cut area.||Coastal Engineering|
|Leg||1. Each straight section of a traverse.|
2. One part of a vessel's track consisting of a single course line.
|Length of wave||The horizontal distance between similar points on two successive waves measured perpendicularly to the crest.||Coastal Engineering|
|Levee||1. An embankment constructed to provide flood protection from seasonal high water.|
2. A dike or embankment to protect land from inundation.
3. A ridge or EMBANKMENT of sand and silt, built up by a stream on its flood plain along both banks of its channel.
4. A large DIKE or artificial EMBANKMENT, often having an access road along the top, which is designed as part of a system to protect land from floods.
|Level of no motion||A level (or layer) at which it is assumed that an isobaric surface coincides with a geopotential surface. A level (or layer) at which there is no horizontal pressure gradient force.||Coastal Engineering|
|Level surface||See geopotential surface.||Coastal Engineering|
|Lever room||A room located near the top and front of the pipeline dredge which houses the operating controls and ganges and affords a full view of operations.||Coastal Engineering|
|Leverman||The person responsible for the physical operation of the dredge. He mans the controls for the winches that move the ladder, each spud and each swing wire. He also monitors gages and instruments for optimum operation of the dredge for maximum production. Also called an operator.||Coastal Engineering|
|Lichenometry||The study of lichens, complex thallophytic plants consisting of algae and fungus growing in symbiotic association, to determine relative ages of sedimentary structures.||Coastal Engineering|
|Lifts||1. (EM 1110-2-5026) Incremental layers of dredged material placements separated from each other by a period of time. The period of time between lifts is usually for dewatering and consolidation purposes. May also be determined by dredging schedule. See also INCREMENTAL PLACEMENT.|
2. The concrete placed between two consecutive horizontal construction joints.
|Light breeze||A wind with velocity from 4 to 6 KNOTS.||Coastal Engineering|
|Light draft||See draft.||Coastal Engineering|
|Light list||A United States Coast Guard publication of navigational markers within a set area.||Coastal Engineering|
|Limber line||See pipe.||Coastal Engineering|
|Limit of authority||The monetary amount set out in the delegation of authority beyond which the designee has no authority to act; or the authority set out by FAR, OCE, or other regulation beyond which the designated person has no authority to act.||Coastal Engineering|
|Limit of backrush (limit of backwash)||See BACKRUSH, BACKWASH.||Coastal Engineering|
|Limiting permissible concentration, lpc|
The LPC for the liquid-phase concentration of dredged material in the water column is the concentration that, after allowance for initial mixing, does not exceed applicable marine-water-quality criteria (WQC) or a toxicity threshold of 0.01 of the acutely toxic concentration. The LPC of the suspended particulate and solid phases is the concentration that will cause unreasonable toxicity or bioaccumulation (see ? 40 CFR 227.27 of the regulations for the complete definition).
|Open water zone.||Coastal Engineering|
|Line item||An account established by OCE for the design or the construction of a part of a total complement or program authorized for design or construction. An element of a program designated by OCE as the lowest level for program accounting and reporting at OCE level.||Coastal Engineering|
|Line of position||(EM 1110-2-1003) Angular or distance measurement used to determine a position when combined with lines of position from other systems.||Coastal Engineering|
|Line of sight||The line of vision.||Coastal Engineering|
|Line spacing||(EM 1110-2-1003) Spacing between successive survey lines of a project area.||Coastal Engineering|
|Line||(Huston. Hydraulic Dredging Principles...) A piece of rope, either fiber or wire, which is in use, or has been cut for a specific purpose, such as a lifeline, heaving line, or lead line. Wire rope is referred to as rope, wire rope, or just wire. a. ancho||Coastal Engineering|
|Lineament||A regional topographic feature of regional extent that is believed to reflect crustal structure.||Coastal Engineering|
|Linear Model||Mathematical model based entirely on linear equations.||Coastal Engineering|
|Liners||1. as in dredged material placement|
2. (EM 1110-2-5026) Physical structures or membranes used to seal off dredged material placement areas to prevent movement of contaminants into lower level or adjacent soil and ground or surface water.
|Littoral drift, Littoral transport|||||
|Littoral transport rate|||||
|Littoral||Nearshore out from shore to the depth of the euphotic zone where it is too dark on the bottom for macrophytes to grow.||Coastal Engineering|
|Load and draught (draft) indicator||Load displacement meter||Coastal Engineering|
|Loading Rates||The rate at which materials (typically suspended sediment, nutrients [N and P], or contaminants) are transported into a water body.||Coastal Engineering|
|Local notice to mariners|
|Local project datum|||||
|Long period constituent|||||
|Long term management strategy, ltms|||||
|Longshore transport rate|||||
|Loop of stationary wave|||||
|Loricas||Glass cell covering.||Coastal Engineering|
|Low maintenance habitat|||||
|Low pass filter|
This is one form of a digital filter. It eliminates noise at low frequencies. For example, an ideal low pass filter would be a square wave in the frequency domain, with a value of 1 for frequencies less than 1/35 cph and zero for frequencies greater than 1/36 cph. This would allow oscillations of periods longer than 36-hrs to pass while those shorter than 36-hrs are removed from the record. A cutoff period of 36-hours was selected to remove tide effects from the record.
|Low plasticity soil||A cohesive soil having a liquid limit water content of less than 50 percent.||Coastal Engineering|
|Low tide terrace||A flat zone of the beach near the low water level.||Coastal Engineering|
|Low tide||See low water.||Coastal Engineering|
|Low water datum||An approximation to the plane of mean low water that has been adopted as a standard reference plane.||Coastal Engineering|
|Low water equinoctial springs||Low water springs near the times of the equinoxes. Expressed in terms of the harmonic constants, it is an elevation depressed below mean sea level by an amount equal to the sum of the amplitudes of the constituents M2, S2, and K2.||Coastal Engineering|
|Low water inequality||See diurnal inequality.||Coastal Engineering|
|Low water interval||See lunitidal interval.||Coastal Engineering|
|Low water line||The line where the established LOW WATER DATUM intersects the shore. The plane of reference that constitutes the LOW WATER DATUM differs in different regions.||Coastal Engineering|
|low water of ordinary spring tides (lwost)||A tidal datum appearing in some British publications, based on low water of ordinary spring tides.||Coastal Engineering|
|Low water reference plane||(EM 1110-2-1003) a hydraulic reference plane based on a particular stage-duration profile (1974 Low Water Reference Plane on the Lower Mississippi River).||Coastal Engineering|
|Low water, LW||The minimum height reached by a falling tide. The low water is due to the periodic tidal forces and the effects of meteorological, hydrologic, and/or oceanographic conditions. For tidal datum computational purposes, the minimum height is not considered a low water unless it contains a tidal low water.||Coastal Engineering|
|Lower high water (LHW)||The lower of the two high waters of any tidal day.||Coastal Engineering|
|Lower low water (LLW)||The lower of the two low waters of any tidal day. The single low water occurring daily during periods when the tide is diurnal is considered to be a lower low water||Coastal Engineering|
|Lower low water datum, LLWD||An approximation of mean lower low water that has been adopted as a standard reference for a limited area and is retained for an indefinite period regardless of the fact |