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


Echo sounder
An instrument for determining the DEPTH of water by measuring the time of travel of a sound-pulse from the surface of a body of water to the bottom and back.

Ecosystem
The living organisms and the nonliving environment interacting in a given area.

Eddy
A current of air, water, or any fluid, forming on the side of the main current, especially one moving in a circle; in extreme cases a whirlpool.

Edge wave
An ocean wave parallel to the 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 wave length offshore.

Eelgrass
A submerged marine plant with very long narrow leaves.

Ekaman 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.

elevation
The distance of a point above a specified surface of constant potential; the distance is measured along the direction of gravity between the point and the surface.

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 natural elutriating agents.

Embankment
An artificial BANK, mound, DIKE, or the like, built to hold back water or to carry a roadway.

Embayed
Formed into a BAY or bays; as an embayed shore.

Embayment
(1) An indentation in a shoreline forming an open BAY. (2) The formation of a BAY.

Emergent coast
A COAST in which land formerly under water has recently been placed above sea level, either by uplift of the land or by a drop in sea level.

Endemic
Native to a specific geographic area.

Entrance
The entrance to a navigable BAY, HARBOR or CHANNEL, INLET or mouth separating the ocean from an inland water body.

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 pr…

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.

Erosion
Wearing away of the land by natural forces. On a BEACH, the carrying away of beach material by wave action, tidal currents or by DEFLATION. (2) (SMP) The wearing away of land by the action of natural forces.

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 called SCARP.

Estuary
(1) A semi-enclosed coastal body of water which has a free connection with the open sea. The seawater is usually measurably diluted with freshwater. (2) The part of the river that is affected by tides. (3) (SMP) The zone or area of water in which freshwater and saltwater mingle and water is usually brackish due to daily mixing and layering of fresh and salt water.

Eulittoral
That part of the LITTORAL ZONE less than 50 m in DEPTH.

Event
An occurrence meeting specified conditions, e.g. damage, a threshold wave height or a threshold water level.

Facies
The sum total of features such as sedimentary rock type, MINERAL content, SEDIMENTARY STRUCTURES, BEDDING characteristics, fossil content, etc. which characterise a sediment as having been deposited in a given environment.

Fairway
The parts of a waterway kept open, and unobstructed, for navigation.

Fathom
A measure of water DEPTH equal to 1.83 m (6 feet).

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.

Fauna
The entire group of animals found in an area.

Feeder beach
An artificially widened beach serving to nourish DOWNDRIFT beaches by natural LITTORAL CURRENTS or other forces.

Feeder current
The currents which flow parallel to shore before converging and forming the NECK of a RIP CURRENT. See Figure 7.

Fetch
The length of unobstructed open sea surface across which the wind can generate waves (GENERATING AREA).

Fetch length
(1) The horizontal distance (in the direction of the wind) over which a wind generates SEAS or creates WIND SETUP. (2) The horizontal distance along open water over which the wind blows and generates waves.

Fjord
A long, narrow arm of the sea, usually formed by entrance of the sea into a deep glacial trough.

Floating bog
A grass or moss growth floating on a pool of water with high content of decayed vegetation, grass and moss roots.

Flocculation
The change which takes place when the dispersed phase of a colloid forms a series of discrete particles which are capable of settling out from the DISPERSION medium. In geological processes, flocculation is almost inevitably a result of a colloidal solution mixing with a solution containing electrolytes, e.g., sea water.

Flood
(1) Period when tide level is rising; often taken to mean the flood current which occurs during this period. (2) A flow above the CARRYING CAPACITY of a CHANNEL.

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…

Flood interval
The interval between the transit of the moon over the meridian of a place and the time of the following flood.

Flood mark
Proof of any kind on the shoreline 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).

Flood routing
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 strength
The FLOOD CURRENT at time of maximum velocity.

Flood tidal delta
The bulge of sand formed at the LANDWARD mouth of TIDAL INLETS as a result of flow expansion.

Flood tide
A nontechnical term used for rising tide or flood current. In technical language flood refers to current. The portion of the tidal cycle between LOW WATER and the following high water. See Figure12.

Floodplain
(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. (2) (SMP) Synonymous with 100-year floodplain. The land area susceptible to being inundated by stream derived waters with a …

Flora
The entire group of plants found in an area.

Flushing time
The time required to replace all the water in an ESTUARY, HARBOR, etc., by action of current and tide.

Foam
The light-colored substance which is made up of an aggregation of bubbles, formed on the surface of liquids by violent agitation.

Foam line
(1) The front of a wave as it advances shoreward, after it has broken. (2) Lines of foam such as those which move around the HEAD of a RIP.

Fog
Vapor condensed to fine particles of water and obscuring vision near the ground.

Following wind
A wind blowing in the same direction as the waves are travelling.

Foreshore
(1) The part of the shore, lying between the BERM CREST and the ordinary LOW WATER mark, which is ordinarily traversed by the UPRUSH and BACKRUSH of the waves as the tides rise and fall. (2) The same as the BEACH FACE where unconsolidated material is present. (3) (SMP) In general terms, the BEACH between MEAN HIGHER HIGH WATER and MEAN LOWER LOW WATER.

Freeboard
The additional height of a structure above design high water level to prevent overflow. Also, at a given time, the vertical distance between the water level and the top of the structure.

Frontager
Person or persons owning, and often living in, property immediately landward of the beach.

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.

Gabion
(1) Steel wire-mesh basket to hold stones or crushed rock to protect a BANK or bottom from EROSION. (2) (SMP) 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.

Gale
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 30 nautical miles per hour.

Gauge
A device for measuring the water level relative to a DATUM.

Generating area
In wave forecasting, a continuous area of the water surface over which the wind blows in essentially the same direction. Sometimes used synonymously with FETCH LENGTH.

Generation of waves
(1) The creation of waves by natural or mechanical means. (2) The creation of and growth of waves by a wind blowing over a water surface for a certain length of time. The area involved is called the GENERATING AREA or FETCH.

Geodesy (or geodetics)
The science of dealing with the investigation of scientific questions connected with the shape and dimensions of the Earth.

Geographic Information System (GIS)
A system of spatially referenced information, including computer programs that acquire, store, manipulate, analyze, and display spatial data.

Geoid
The equipotential surface of the Earth`s gravity field which best fits, in the least squares sense, MEAN SEA LEVEL.

Geology
The science which treats of the origin, history and structure of the Earth, as recorded in rocks; together with the forces and processes now operating to modify rocks.

Geomorphology
(1) That branch of physical geography which deals with the form of the Earth, the general configuration of its surface, the distribution of the land, water, etc. (2) The investigation of the history of geologic changes through the interpretation of topographic forms.

Geophysics
The study of the physical characteristics and properties of the Earth.

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.

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.

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.

Gravel
(1) Loose, rounded fragments of rock, larger than sand, but smaller than cobbles. (2) Small stones and pebbles, or a mixture of these with sand.

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. See RIPPLE. See Figure 10.

Great diurnal range
The difference in height between MEAN HIGHER HIGH WATER and MEAN LOWER LOW WATER. The expression may also be used in the contracted form diurnal range.

Groin
(1) A shore-protection structure (built usually to trap LITTORAL DRIFT or retard EROSION of the shore). It is narrow in width (measured parallel to the shore) and its length may vary from tens to hundreds of meters (extending from a point landward of the shoreline out into the water). GROINS may be classified as permeable (with openings through them) or impermeable (a solid or nearly solid structure). (2) (SMP) A barrier-type structure extending from the BACKSHORE or stream bank into a water bod…

Groin bay
The BEACH compartment between two groins.

Groin system
A series of GROINS acting together to protect a section of BEACH. Commonly called a GROIN field.

Ground Penetrating Radar (GPR)
A geophysical technology that uses radio waves to detect buried objects and the internal structure of landforms.

Ground swell
(1) Long high SWELL in DEEP WATER. (2) Also, this swell as if rises to prominent height in shoal water.

Ground water
Subsurface water occupying the zone of saturation. In a strict sense the term applied only to water below the WATER TABLE.

Group velocity
The velocity at which a wave group travels. In DEEP WATER, it is equal to one-half the individual wave velocity.

Gulf
A relatively large portion of sea, partly enclosed by land.

Gut
(1) A narrow passage such as a strait or INLET. (2) A CHANNEL in otherwise shallow water, generally formed by water in motion.

Guyot
Flat-topped seamount.

Habitat
The place where an organism lives.

Halcocline
A zone in which salinity changes rapidly.

Half-tide level
A plane midway between MEAN HIGH WATER and MEAN LOW WATER, also called MEAN TIDE LEVEL.

Harbor
A water area nearly surrounded by land, sea walls, BREAKWATERS or artificial dikes, forming a safe anchorage for ships.

Hard defenses
A general term applied to impermeable COASTAL DEFENSE structures of concrete, timber, steel, masonry, etc, which reflect a high proportion of INCIDENT WAVE energy.

Head
(1) A comparatively high promontory with either a CLIFF or steep face. It extends into a large 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.

Headland
A land mass having a considerable ELEVATION. See Figure 13.

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 sea
A sea in which the waves run high.

High seas
This term, in municipal and international law, denotes all that 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, also called OPEN SEA.

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.

High water line
The intersection of MEAN HIGH WATER with the shore. The shoreline delineated on the nautical charts of the U.S. Coast and Geodetic Survey is an approximation of the mean high water line.

High water mark
A reference mark on a structure or natural object, indicating the maximum stage of tide or flood.

Higher high water (HHW)
The higher of the two high waters of any tidal day. The single high water occurring daily during periods when the tide is DIURNAL is considered to be HIGHER HIGH WATER. See Figure 11.

Higher low water (HLW)
The higher of the two low waters of any tidal day. See Figure 11.

Hindcasting
In wave prediction, the retrospective forecasting of waves using measured wind information. See also WAVE HINDCASTING.

Hinterland
The region lying inland from the COAST.

Historic event analysis
Extreme analysis based on hindcasting typically ten events over a period of 100 years.

Hook
A spit or narrow CAPE, turned landward at the outer end, resembling a hook in form.

Horizon
(1) The line or circle which forms the apparent boundary between Earth and sky. (2) (Geological) A plane in rock strata characterized by particular features, as occurrence of distinctive fossil species. One of the series of distinctive layers found in a vertical cross-section of any well-developed soil.

Hurricane
A cyclonic storm, usually of tropic origin, covering an extensive area, and containing winds in excess of 75 miles per hour.