9. Glossary

Abrasion platform	A rock or clay platform which has been worn by the processes of abrasion (i.e. frictional erosion by material transported by wind and waves)
Accretion	The accumulation of (beach) sediment, deposited by natural fluid flow processes
Aeolian	Caused by the action of the wind
Anthropogenic	Caused by the action of people
Apron	Layer of stone, concrete or other material to protect the toe of a seawall
Beach profile	A cross-section taken perpendicular to a given beach contour; the profile may include the face of a dune or seawall, extend over the backshore, across the foreshore, and seaward underwater into the nearshore zone
Breaching	Failure of the beach head allowing flooding by tidal action
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 processes	Collective term covering the action of natural forces on the shoreline, and nearshore seabed
Conservation	The protection of an area, or particular element within an area, whilst accepting the dynamic nature of the environment and therefore allowing change
Deflation	Erosion of dunes by wind action
Diffraction	Process affecting wave propagation, by which wave energy is radiated normal to the direction of wave propagation into the lee of an island or breakwater
Fetch	Distance over which a wind acts to produce waves - also termed fetch length.
Foreshore	The intertidal area below highest tide level and above lowest tide level
Groyne	Narrow, roughly shore-normal structure built to reduce longshore currents, and/ or to trap and retain beach material. Most groynes are of timber or rock, and extend from a seawall, or the backshore, well onto the foreshore and rarely even further offshore. In the USA and historically called a groin
Hard defences	General term applied to impermeable coastal defence structures of concrete, timber, steel, masonry etc., which reflect a high proportion of incident wave energy, cf soft defences
Intertidal	The zone between the high and low water marks
Longshore	Parallel and close to the coastline
Longshore drift	Movement of (beach) sediments approximately parallel to the coastline
Machair	Relatively smooth, shell-rich, blown sand surface stabilised by vegetation forming a continuous short grass and herb rich sward
Nearshore	The zone which extends from the swash zone to the position marking the start of the offshore zone, typically at water depths of the order of 20m
Numerical modelling	Refers to analysis of coastal processes using computational models
Offshore	The zone beyond the nearshore zone where sediment motion induced by waves alone effectively ceases and where the influence of the sea bed on wave action is small in comparison with the effect of wind
Overtopping	Water carried over the top of a coastal defence due to wave run-up exceeding the crest height
Pocket Beach	A beach, usually small, between two headlands
Preservation	Static protection of an area or element, attempting to perpetuate the existence of a given `state'
Reef	A ridge of rock or other material lying just below the surface of the sea
Reflected wave	That part of an incident wave that is returned (reflected) seaward when a wave impinges on a beach, seawall or other reflecting surface
Refraction (of water waves)	The process by which the direction of a wave moving in shallow water at an angle to the contours is changed so that the wave crests tend to become more aligned with those contours
Revetment	A sloping surface of stone, concrete or other material used to protect an embankment, natural coast or shoreline against erosion
Shoaling	Decrease in water depth. The transformation of wave profile as they propagate inshore
Soft defences	Usually refers to beaches (natural or designed) but may also relate to energy-absorbing beach-control structures, including those constructed of rock, where these are used to control or redirect coastal processes rather than opposing or preventing them
Spit	A long narrow accumulation of sand or shingle, lying generally in line with the coast, with one end attached to the land the other projecting into the sea or across the mouth of an estuary - see also ness
Surge	Changes in water level as a result of meteorological forcing (wind, high or low barometric pressure) causing a difference between the recorded water level and that predicted using harmonic analysis, may be positive or negative
Swell (waves)	Remotely wind-generated waves. Swell characteristically exhibits a more regular and longer period and has longer crests than locally generated waves
Tombolo	Coastal formation of beach material developed by refraction, diffraction and longshore drift to form a `neck' connecting a coast to an offshore island or breakwater (see also salient)
Wave climate	The seasonal and annual distribution of wave height, period and direction
Wavelength	Straight-line distance between two successive wave crests
Wave period	The time taken for two successive wave crests to pass the same point
Wave rose	Diagram showing the long-term distribution of wave height and direction
Wind sea	Wave conditions directly attributable to recent winds, as opposed to swell