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ECY - Glossary of Coastal Terminology Category: Earth and Environment > Coast Date & country: 13/09/2007, USA Words: 756

Abrasion
Frictional EROSION by material transported by wind and waves.

Accelerometer
A device used in wave buoys for measuring acceleration.

Accretion
The accumulation of (beach) sediment, deposited by natural fluid flow processes.

Active margin
A margin consisting of a CONTINENTAL SHELF, a CONTINENTAL SLOPE, and an oceanic trench.

Aeolian deposits
Wind-deposited sediments, such as sand DUNES. See Figure 8.

Aggradation
The geologic process by which various parts of the surface of the earth are raised in ELEVATION or built up by the deposition of material transported by water or wind.

Allochtonous
A term applied shelves that presently experience deposition of river-derived sediments. See also DETRITUS.

Alluvial deposits
Detrital material which is transported by a river and deposited â€` usually temporarily â€` at points along the FLOODPLAIN of a river. Commonly composed of sands and GRAVELS.

Alongshore
Parallel to and near the shoreline; same as LONGSHORE.

altimeter
An instrument that determines its distance above a particular surface.

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.

altimeter, lidar
See ALTIMETER, LASER, and lidar.

Amplitude
Half of the peak-to-trough range (or height) of a wave. See Figure13.

Angle of repose
The maximum slope (measured from the HORIZON) at which soils and loose materials on the banks of CANALS, rivers or embankments stay stable.

Aquifer
A geologic formation that is water-bearing, and which transmits water from one point to another.

aseismic ridge
A submarine ridge with which no earthquakes are associated.

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.

Attenuation
The loss or dissipation of wave energy, resulting in a reduction of wave height (AMPLITUDE).

Autochthonous
A term applied to shelves on which older shelf sediments are primarily being reworked by modern shelf processes.

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.

Avulsion
(1) Rapid EROSION of the shoreland by waves during a storm. (2) A sudden cutting off of land by flood, currents or change in course of a body of water.

Backshore
(1) The upper part of the active BEACH above the normal reach of the tides (high water), but affected by large waves occurring during a high. (2) (SMP) The accretion or erosion zone, located landward of ordinary high tide, which is normally wetted only by storm tides.

Backwash
(1) The seaward return of the water following the uprush of the waves. Also called backrush or run down. (2) Water of waves thrown back by an obstruction such as a ship, BREAKWATER, CLIFF, etc.

Backwash ripples
Low amplitude ripple marks formed on fine sand beaches by the BACKWASH of the waves.

Bank
The rising ground bordering a lake, river or sea.

Bar
An offshore ridge or mound of sand, GRAVEL, or other unconsolidated material which is submerged (at least at high tide), especially at the mouth of a river or ESTUARY, or lying parallel to, and a short distance from, the BEACH. See Figure 2.

Barrier beach
A BAR essentially parallel to the shore, which has been built up so that its crest rises above the normal high water level. Also called BARRIER ISLAND and OFFSHORE BARRIER.

Barrier island
A detached portion of a BARRIER BEACH between two inlets. See Figure6.

Barrier spit
Similar to a BARRIER ISLAND, only connected to the mainland.

Basin
A large submarine DEPRESSION of a generally circular, elliptical or oval shape.

Bathymetry
The measurement of DEPTHS of water in oceans, seas and lakes; also the information derived from such measurements.

Bay
A recess or INLET in the shore of a sea or lake between two capes or headlands, not as large as a GULF but larger than a COVE. See also BIGHT, EMBAYMENT. See Figure 5.

Baymouth bar
A BAR extending partly or entirely across the mouth of a bay.

Beach
(1) A deposit of non-cohesive material (e.g. sand, GRAVEL) situated on the interface between dry land and the sea (or other large expanse of water) and actively 'worked' by present-day hydrodynamics processes (i.e. waves, tides and CURRENTS) and sometimes by winds. (2) 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. The seaward limit of a BEACH â€` …

Beach crest
The point representing the limit of high tide storm wave run-up.

Beach erosion
The carrying away of beach materials by wave action, tidal CURRENTS, LITTORAL CURRENTS or wind.

Beach face
The section of the BEACH normally exposed to the action of wave UPRUSH. The FORESHORE of the BEACH.

Beach head
The CLIFF, dune or sea wall looming the landward limit of the active BEACH.

Beach nourishment
The process of replenishing a BEACH by artificial means; e.g., by the deposition of dredged materials, also called beach replenishment or beach feeding.

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.

Beach Ridge
A low extensive ridge of beach material piled up by storm waves landward of the BERM. Usually consists of very coarse sand, GRAVEL or shells. Occurs singly or as a series of more or less parallel ridges.

Beach scarp
(1) An almost perpendicular slope along the beach FORESHORE; an erosional feature due to wave action, it may vary in height from a few centimeters to several meters, depending on wave action and the nature and composition of the BEACH. See ESCARPMENT. See ESCARPMENT. (2) (SMP) A steep slope produced by wave erosion.

Beach width
The horizontal dimension of the BEACH measured normal to the shoreline.

Beaufort Scale
The relationship between sea state and wind speed. The Beaufort Scale can be used to estimate wind speed at sea, but is valid only for waves generated within the local weather system, and assumes that there has been sufficient time for a fully developed sea to have become established.

Bed
The bottom of a watercourse, or any body of water.

Bed load
Heavy or large sediment particles that travel near or on the BED.

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. See also CROSS-BEDDING, SEDIMENTARY STRUCTURES.

Bench
(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.

Bench mark
A mark affixed to a permanent object in tidal observations, or in a survey, to furnish a DATUM level.

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.

Benefits
The economic 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.

Benthic
Pertaining to the sub-aquatic bottom.

Benthos
Those animals who live on the sediments of the sea floor, including both mobile and non-mobile forms.

Berm
(1) On a BEACH

Berm breakwater
Rubble mound with horizontal BERM of armour stones at about sea-side water level, which is allowed to be (re)shaped by the waves.

Berm crest
The seaward limit of the BERM, or the minimum DEPTH of a submerged BERM; also called berm edge.

Bifurcation
Location where a river separates in two or more reaches or branches (the opposite of a CONFLUENCE).

Bight
A slight indentation in a COAST forming an open BAY, usually crescent shaped.

Blowout
A DEPRESSION on the land surface caused by wind EROSION.

Bluff
A high, steep BANK or CLIFF.

Bog
(SMP) 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.

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.

Bottom boundary layer
The lower portion of the water flow that experiences frictional retardation based on its proximity to the BED. See also VELOCITY PROFILE.

Boulder
A rounded rock on a BEACH, greater than 256 mm in diameter, larger than a cobble. See also GRAVEL, shingle.

Box gage
A tide gage 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 gage the float supported a graduated rod which rose and fell with the tide.

Breaching
Failure of the BEACH HEAD or a DIKE allowing flooding by tidal action.

Breaker
A wave that has become so steep that the crest of the wave topples forward, moving faster than the main body of the wave. Breakers may be roughly classified into four kinds, although there is much overlap (see Figure 2):

Breaker index
Maximum ratio of wave height to water DEPTH in the surf zone, typically 0.78 for SPILLING WAVES, ranging from about 0.6 to 1.5.

Breaker zone
The zone within which waves approaching the COASTLINE commence breaking, typically in water DEPTHS of between 5 m and 10 m.

Breaking depth
The still-water DEPTH at the point where the wave breaks.

Breakwater
(1) A structure protecting a HARBOR, anchorage, or BASIN from waves. (2) (SMP) Offshore structure aligned parallel to the SHORE, sometimes shore-connected, that provides protection from waves.

Buffer area
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.

Bulkhead
(1) A structure separating land and water areas, primarily designed to resist earth pressures. (2) 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.

Buoy
A float; especially a floating object moored to the bottom, to mark a CHANNEL, anchor, shoal rock, etc. Some common types include

Buoyancy
The resultant upward forces, exerted by the water on a submerged or floating body, equal to the weight of the water displaced by this body.

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 as well as movement caused by man.

California current
A deep-ocean boundary current that flows south-southeasterly along the U.S. west coast. The current is shallow, broad and slow moving carrying cold, nutrient poor waters toward the equator.

Calm
The condition of the water surface when there is no WIND WAVES or SWELL.

Camera, aerial
A camera especially designed for photographing the Earth`s surface from above the ground; usually carried in aircraft and Earth-orbiting satellites.

Camera, metric
A camera designed particularly for photogrammetry, constructed so that the image is distorted geometrically as little as possible and the camera characteristics do not change from photograph to photograph.

Canal
An artificial watercourse cut through a land area for such uses as navigation and irrigation.

Cape
A relatively extensive 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.

Capillary wave
A wave whose velocity or propagation is controlled primarily by the surface tension of the liquid in which the wave is travelling. A water wave in which the wave length is less than 2.5 cm is considered to be a capillary wave, while waves longer than 2.5 cm and shorter than 5cm are in an indeterminate zone between CAPILLARY and GRAVITY WAVES. See also RIPPLE. See Figure 10.

Carrying capacity
The maximum number of species that any particular area can support over an extended period of time.

Cartography
The science and art of making maps.

Celerity
The magnitude of WAVE VELOCITY.

Change of tide
The change of one tide condition (rising or falling) for the other (falling or rising), or of one TIDAL CURRENT direction flow for the other.

Channel
(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) The deepest portion of a stream, BAY, or strait through which the main volume of CURRENT of water flows. (4) (SMP) An open conduit for water either naturally or artificially created, but…

Chart datum
The plane or level to which soundings, tidal levels or water DEPTHS are referenced, usually LOW WATER DATUM. See also DATUM PLANE and REFERENCE PLANE.

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.

Clastic rocks
Rocks built up of fragments which have been produced by the processes of weathering and EROSION, and in general transported to a point of deposition.

Clay
A fine grained 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.

Cliff
A high steep face of rock.

Climate change
Refers to any long-term trend in MEAN SEA LEVEL, wave height, wind speed, drift rate etc.

Co-tidal lines
Lines which link all the points where the tide is at the same stage (or phase) of its cycle.

Coast
A strip of land of indefinite length and width (may be tens of kilometers) that extends from the SEASHORE inland to the first major change in terrain features.

Coastal currents
(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 forcing
The natural processes that drive coastal hydro- and morphodynamics (e.g. winds, waves, tides, etc).

Coastal management
The development of a strategic, long-term and sustainable land use policy, sometimes also called shoreline management.