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This glossary is intended to provide the reader with definitions of some coastal terminologies which may have been encountered in this website, or which may be useful for coastal zone management research purposes.
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Accretion
The deposition of sediment, sometimes indicated by the seaward advance of a shoreline indicator such as the water line, the berm crest, or the vegetation line.
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Active Beach
The portion of the littoral system that is frequently (daily or at least seasonally) subject to transport by wind, waves, and currents.
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Algal Bloom
A sudden increase in the amount of marine algae (seaweed) often caused by high levels of phosphates, nitrates, and other nutrients in the nearshore area.
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Alien Species
(Also called introduced, exotic, or non-indigenous species) - A species that has been transported by human activity, intentionally or accidentally, into a region where it does not occur naturally.
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Alongshore
Parallel to and near the shoreline (also referred to as longshore).
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Anoxic
Refers to an environment that contains little or no dissolved oxygen and hence little or no benthic marine life. These conditions often arise in deep water locations where physical circulation of seawater is limited.
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Aquaculture
The cultivation of aquatic organisms.
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Armouring
The placement of fixed engineering structures, typically rock or concrete, on or along the shoreline to reduce coastal erosion. Armoring structures include seawalls, revetments, bulkheads, and rip rap (loose boulders).
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Ballast Water
Water carried by a vessel to improve its stability.
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Bathymetric chart
A topographic map of the bed of the ocean, with depths indicated by contours (isobaths) drawn at regular intervals.
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Bathymetry
The measurement of water depths in oceans, seas, and lakes; also information derived from such measurements .
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Beach
An accumulation of loose sediment (usually sand or gravel) along the coast.
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Beach Face
The section of the beach normally exposed to the action of the wave uprush. Also referred to as the foreshore of a beach.
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Beach Loss
A volumetric loss of sand from the active beach.
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Beach Narrowing
A decrease in the useable beach width caused by erosion.
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Beach Nourishment
The technique of placing sand fill along the shoreline to widen the beach.
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Beach Profile
A cross-sectional plot of a shore-normal topographic and geomorphic beach survey, usually in comparison to other survey dates to illustrate seasonal and longer-term changes in beach volume.
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Beach Width
The horizontal dimension of the beach measured normal to the shoreline and landward of the high water mark line on coasts.
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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.
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Berm
A geomorphological feature usually located at mid-beach and characterized by a sharp break in slope, separating the flatter backshore from the seaward-sloping foreshore.
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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.
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Biological Diversity
(Also called biodiversity) - The diversity of life, often divided into three levels: genetic (diversity within species), species (diversity among species), and ecosystem (diversity among ecosystems).
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Biomass
The mass of living matter per unit of habitat (e.g. volume of water or area of bottom). Also referred to as standing crop or standing stock.
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Blowout
a depression on the land surface caused by wind erosion.
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BOD
Biochemical (or Biological) Oxygen Demand - high figures suggest pollution or eutrophication.
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Breaker
A wave breaking on a shore or 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 beach face during runback.
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Breaker Depth
The still-water depth at the point where a wave breaks. Also called breaking depth.
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Breaker Zone
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.
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Breakwater
A man-made structure protecting a shore area, harbor, anchorage, or basin from waves.
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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.
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Building Setback
The county required seaward limit of major construction for a coastal property. Building setbacks in Barbados are set at 30m (100 feet) from the high water mark for beaches and 10m (30 feet) for cliffs measured from the landward point of under cut.
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Clay
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.
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Climate
The characteristic weather of a region, particularly regarding temperature and precipitation, averaged over some significant internal of time (years).
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Coast
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. The part of a country regarded as near the coast.
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Coastal Current
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.
For navigational purposes, the term is used to designate a current in coastwise shipping lanes where the tidal current is frequently rotary.
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Coastal Defense
General term used to encompass both coast protection against erosion and sea defense against flooding.
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Coastal Dunes
Dunes within the coastal upland, immediately landward of the active beach.
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Coastal Erosion
The wearing away of coastal lands, usually by wave attack, tidal or littoral currents, or wind. Coastal erosion is synonymous with shoreline (vegetation line) retreat.
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Coastal Plain
The low-lying, gently-sloping area landward of the beach often containing fossil sands deposited during previously higher sea levels.
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Coastal Processes
Collective term covering the action of natural forces on the shoreline, and near shore seabed
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Coastal Strip
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, coastal defense activities take place. In this strip often there may be restrictions to land use.
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Coastal Upland
The low-lying area landward of the beach that sometimes contains unconsolidated sediments.
The coastal upland is bounded by the hinterland (the higher-elevation areas dominated by bedrock and steeper slopes).
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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 coastal development in economical, ecological and social terms.
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Cobble (Cobblestone)
A rock fragment between 64 and 256 mm in diameter usually rounded.
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Conservation
The management of a natural resource for the protection, maintenance, rehabilitation, restoration, and/or enhancement of populations and ecosystems.
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Contamination
An anthropogenic increase in the concentration of a substance in the marine environment.
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Continental Shelf
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.
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).
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Continental Slope
The declivity from the offshore border of the continental shelf to oceanic depths. It is characterized by a marked increase in slope.
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Coral
Colonial animals in the phylum Cnidaria; mainly those that build reefs. "Coral" is also often used to refer to the hard, calcareous coral skeleton.
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Coral Bleaching
A phenomenon in which corals under stress (e.g., by elevated water temperature) expel their symbiotic algae (zooxanthellae) in large numbers, or the concentration of algal photosynthetic pigments decreases. As a result, the corals' white skeletons show through their tissue and they appear bleached.
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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.
Extensive limestone structures built largely by corals. They occur primarily in shallow tropical and provide habitat for a large variety of other marine life forms.
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Crest
Highest point on a beach face, breakwater, or seawall.
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Crest of Wave
The highest part of a wave.
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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.
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Current, Littoral
Any current in the littoral zone caused primarily by wave action; e.g., longshore current, rip current.
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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.
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Deflation
A lowering of the beach profile.
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Detritus
The particulate, organic remains and waste of organisms. It constitutes a major food source in marine ecosystems.
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Diffuse Sources of Pollution
(Also called non-point sources) Multiple, not easily identifiable sources of pollution (e.g., agriculture, urban areas).
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Downdrift
Flow in the direction of net longshore sediment transport.
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Downstream
Along coasts with obliquely approaching waves there is a longshore (wave-driven) current.
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Dredging
The practice of excavating or displacing the bottom or shoreline of a water body.
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Dumping
Any deliberate disposal at sea of wastes or other matter, or any deliberate disposal of vessels or other man-made structures .
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Dune
A landform characterized by an accumulation of wind-blown sand, often vegetated.
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Dune Restoration
The technique of rebuilding an eroded or degraded dune through one or more various methods (sand fill, drift fencing, revegetation, etc.).
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Dune Walkover
Light construction that provides pedestrian access without trampling dune vegetation.
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Dynamic Equilibrium
A system in flux, but with influxes equal to outfluxes.
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Ecology
The branch of science studying the interactions among living things and their environment.
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Ecosystem
The living organisms and the nonliving environment interacting in a given area, encompassing the relationships between biological, geochemical, and geophysical systems.
A community or several communities of organisms together with their physical environment. A conceptual view of interaction within and independence among species and communities emphasizing the nature of the flow of material and energy among these parts and the feedback loops from one part to another.
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El Nio
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.
A warm current that usually appears around Christmas off the coast of Ecuador and Peru . It is often used to refer to episodic (3-5 year) events when the current is particularly intense and dominates the local population of organisms (the abundance of fish in particular). Such events lead to wider regional or global ocean-atmospheric perturbations whose manifestations range from increased sea surface temperatures in the tropical East Pacific to aberrant rainfall patterns. (see also ENSO ).
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Endemic Species
Species native to and restricted to specific geographic areas.
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ENSO (El Nio/Southern Oscillation)
A cyclical, large-scale changes in atmospheric and ocean patterns in which, among other things, warm surface water in the Pacific moves further to the east than normal. (See also El Niño ).
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Environmental Impact Assessment (EIA)
A process by which the consequences of planned development projects are evaluated as an integral part of planning the project.
The analysis of biological, physical, social and economic factors to determine the environmental and social consequences of a proposed development action. The goal of the EIA is to provide policy makers with the best available information in order to minimize economic costs and maximize benefits associated with a proposed development.
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Environmental Valuation
Procedures for valuing changes in environmental goods and services, whether or not they are traded in markets, by measuring the changes in the consumer or producer surpluses associated with these environmental goods.
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Erosion
The loss of sediment, sometimes indicated by the landward retreat of a shoreline indicator such as the water line, the berm crest, or the vegetation line.
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Erosion Hotspots
Areas where coastal erosion has threatened shoreline development or infrastructure. Typically, the shoreline has been armored and the beach has narrowed considerably or been lost.
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Erosion Watch Spots
Areas where the coastal environment will soon be threatened if shoreline erosion trends continue.
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Estuary
The region where a river meets the marine environment. It is characterized by variable salinity and often by high biological productivity.
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Eutrophication
Increased primary production caused by the anthropogenic enrichment of a water body with nutrients. (See also primary production and nutrients ).
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Fauna
The entire group of animals found in an area.
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Fore Reef
The seaward side of a reef (usually coral); in places a steep slope covered with reef talus.
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Foredune
The front dune immediately behind the backshore.
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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.
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Gabion
Steel wire-mesh basket to hold stones or crushed rock to protect a bank or bottom from erosion. 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 (although not recommended) on heavy erosion coastal areas to retard wave action.
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Geographical Information System (GIS)
Database of information which is geographically referenced, usually with an associated visualization system.
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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.
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Gravel
Unconsolidated natural accumulation of rounded rock fragments coarser than sand but finer than pebbles (2-4 mm diameter).
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Greenhouse Gases
Gases that trap heat radiating from the Earth's surface, thereby warming the lower atmosphere.
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Groundwater
Water that occupies pores and crevices in rock and soil, below the surface of the Earth. The upper limit of the groundwater is the water table, whose level varies according to the quantity of water entering and extracted from the groundwater. (See also aquifers).
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Groyne
Narrow, roughly shore-normal structure built to reduce longshore currents, and/or to trap and retain littoral material. Most groins are of rock and extend from the backshore, well onto the foreshore and rarely even further offshore.
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Habitat
The physical space where an organism, population or species lives. Habitats are usually categorized by particular physical or biological characteristics (e.g., coral reefs, mangrove forests).
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Harbour
Any protected water area affording a place of safety for vessels. A harbor may be natural or man-made.
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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.
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High Water Line
In strictness, the intersection of the plane of mean high water with the shore. For specific occurrences, the highest elevation on the shore reached during a storm or rising tide, including meteorological effects.
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High Water Mark
A reference mark on a structure or natural object, indicating the maximum stage of tide or flood.
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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.
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Hurricane Path or Track
Line of movement (propagation) of the eye through an area.
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Hydrography
The description and study of seas, lakes, rivers and other waters; the science of locating aids and dangers to navigation; the description of physical properties of the waters of a region.
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Hypoxic Waters
Waters with a low concentration of oxygen.
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Incident wave
A wave moving landward.
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Integrated Coastal Management (ICM)
The management of sectoral components (e.g., fisheries, forestry, agriculture, tourism, urban development) as part of a functional whole (a holistic approach to management). In ICM the focus is on the users of natural resources, not on the stock per se of these resources. Frequently used synonyms for ICM are integrated coastal area management (ICAM) and integrated coastal zone management (ICZM).
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Leeward
The direction toward which the wind is blowing; The direction toward which waves are travelling.
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Littoral
Of or pertaining to a shore, especially of the sea. Often used as a general term for the coastal zone influenced by wave action, or, more specifically, the shore zone between the high and low water marks.
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Littoral Cell
A reach of the coast that is isolated sedimentologically from adjacent coastal reaches and that features its own sources and sinks. Isolation is typically caused by protruding headlands, submarine canyons, inlets, and some river mouths that prevent littoral sediment from one cell to pass into the next.
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Littoral Transport
The movement of beach material in the littoral zone by waves and currents. Includes movement parallel (longshore drift) and sometimes perpendicular (cross-shore transport) to the shore; Also referred to as littoral drift.
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Littoral Transport Rate
The rate of transport of sedimentary material parallel or perpendicular to the shore in the littoral zone. Usually expressed in cubic metres (cubic yards) per year. Commonly synonymous with longshore transport rate.
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Littoral Zone
In beach terminology, an indefinite zone extending seaward from the shoreline to just beyond the breaker zone.
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Longshore
Parallel to and near the shoreline; Also referred to as alongshore.
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Longshore Transport
Sediment transport down the beach (parallel to the shoreline) caused by longshore currents and/or waves approaching obliquely to the shoreline.
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Macro-tidal
Tidal range greater than 4 m.
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Mangrove Forest
A community of salt-tolerant trees and shrubs, with many other associated organisms, that grows on some tropical and sub-tropical coasts in a zone roughly coinciding with the intertidal zone.
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Mariculture
The cultivation of marine organisms.
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Marina
A specially designed harbour with moorings for pleasure yachts and small boats.
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Marker, reference
A mark of permanent character close to a survey station, to which it is related by an accurately measured distance and azimuth (or bearing).
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Marsh, Salt
A marsh periodically flooded by salt water.
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Mean High Water (MHW)
The average height of the high water over a 19-year period. For shorter periods of observations, corrections are applied to eliminate known variations and reduce the results to the equivalent of a mean 19-year value. All high water heights are included in the average where the type of tide is either semi-diurnal or mixed.
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Mean Low Water (MLW)
The average height of the low water over a 19-year period. For shorter periods of observations, corrections are applied to eliminate known variations and reduce the results to the equivalent of a mean 19-year value. All low water heights are included in the average where the type of tide is either semi-diurnal or mixed.
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Meso-tidal
Tidal range between 2m and 4m.
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Micro-tidal
Tidal range less than 2m.
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Natural Resources
May be classified as non-renewable (e.g. coal, oil) and renewable. The latter may further be classified as unconditionally renewable (e.g. solar, tidal or wind energy) and conditionally renewable (e.g. fish, forest products). Conditionally renewable sources will last indefinitely if not over-exploited because that part of the resource that is used can be replaced through natural processes.
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Nearshore Current System
The current system characterised primarily by wave action in and near the breaker zone, and which consists of four parts: the shoreward mass transport of water; longshore currents; seaward return flow, including rip currents; and the longshore movement of the expanding heads of rip currents. See also nearshore circulation.
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Non-governmental Organisation (NGO)
An organisation, usually non-profit, that is not part of the central, local, or municipal government.
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Nutrients
Substances that are essential for the growth of marine organisms that perform primary production (algae, bacteria, and plants). Excess nutrients, especially nitrogen and phosphorus, can be major pollutants.
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Oceanography
The study of the sea embracing and indicating all knowledge pertaining to the sea's physical boundaries, the chemistry and physics of the seawater, marine biology, and marine geology.
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Offshore Current
Any current in the offshore zone. Also refers to any current flowing away from shore.
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Outcrop
A surface exposure of bare rock, not covered by soil or vegetation.
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Oversplash
The water that splashes over the top of a breakwater, seawall or other coastal defence structure.
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Overwash
Transport of the sediment landward of the active beach by coastal flooding during a tsunami, hurricane, or other event with extreme waves.
The part of the uprush that runs over the crest of a berm of a structure and does not flow directly back to the ocean or lake.
- The effects of waves overtopping a coastal defence, often carrying sediment landwards which is then lost to the beach system.
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Patch Reef
a mound like or flat-topped organic reef, generally less than 1 km across, frequently forming part of a larger reef complex.
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Photic Zone
The zone extending downward from the ocean surface within which the light is sufficient to sustain photosynthesis. The depth of this layer varies with water clarity, time of year and cloud clover, but is about 100m in the open ocean.
- It may be considered the depth to which all light is filtered out except for about one percent and may be calculated as about two and a half-times the depth of a secchi disk reading.
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Photomosaic
An assemblage of photographs, each of which shows part of a region, put together in such a way that each point in the region appears once and only once in the assemblage, and scale variation is minimised.
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Pier
A structure, ususally of open construction, extending out into the water from the shore, to serve as a landing place, recreational facility, etc., rather than to afford coastal protection or affect the movement of water. A term sometimes improperly applied to jetties.
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Pile
A long, heavy timber or section of concrete or metal that is driven or jetted into the earth or seabed to serve as a support or protection.
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Pollution (marine)
The introduction by man, directly or indirectly, of substances or energy into the marine environment (including estuaries) resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to maritime activities including fishing, impairment of quality for use of sea water and reduction of amenities.
- The contamination of the environment or poisonous substances.
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POPs (persistent organic pollutants)
A diverse group of chemicals that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment. A group of twelve POPs (the "dirty dozen") have been initially selected for international action by the International Programme on Chemical Safety (IPCS).
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Port
A place where vessels may discharge or receive cargo; it may be the entire harbour including its approaches and anchorages, or only the commercial part of a harbour where the quays, wharves, facilities for transfer of cargo, docks, and repair shops are situated. Protection may be provided by natural or artificial features.
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Precautionary approach
The essence of the approach is expressed in Principle 15 of the Rio Declaration that states "Where there are threats of serious or irreversible damage, lack of scientific certainty shall not be used as a reason to postponing cost-effective measures to prevent environmental degradation." The approach is concerned with avoiding risk that has not been assessed, i.e. uncertainty.
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Reflection
The process by which the energy of the wave is returned seaward.
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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: the part of the wave advancing in shallower water moves more slowly than that part still advancing in deeper water, causing the wave crest to bend toward alignment with the underwater contours.
- The bending of wave crests by currents.
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Rip Current
A strong surface current flowing seaward from the shore. It usually appears as a visible band of agitated water and is the return movement of water piled up on the shore by incoming waves and winds. With the seaward movement concentrated in a limited band its velocity is somewhat accumulated. A rip consists of three parts: the feeder currents flowing parallel to the shore inside the breakers; the neck, there the feeder currents converge and flow through the breakers in a narrow band or "rip"; and the head of rip, where the current widens and slackens outside of the breaker line. A rip current is often miscalled a rip tide.
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Riprap
A protective layer or facing of quarry stone, usually well graded within wide size limit, randomly placed to prevent erosion, scour, or sloughing of an embankment or bluff; also the stone so used. The quarry tone is placed in a layer at least twice the thickness of the 50 percent size, or 1.25 times the thickness of the largest size stone in the gradation.
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Rock
An aggregate of one or more minerals; or a body of undifferentiated mineral matter. The three classes of rocks are: (a) igneous - crystalline rocks formed from molten material (e.g. granite and basalt); (b) sedimentary - resulting from the consolidation of loose sediment that has accumulated in layers (e.g. sandstone, shale and limestone); (c) metamorphic - formed from pre-exisiting rock as a result of burial, heat and pressure.
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Sand
Sediment particles, often largely composed of quartz, with a diameter of between 0.062mm and 2mm, generally classified as fine, medium, coarse or very coarse. Beach sand may sometimes be composed of organic sediments such as calcareous reef debris or shell fragments.
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Sea
A large body of salt water, second in rank to an ocean, more or less landlocked and generally part of, or connected with, an ocean or a larger sea. Examples: Mediterranean Sea; South China Sea.
- Waves caused by wind at the place and time of observation.
- State of the ocean surface, in regard to waves.
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Seagrass
Members of marine seed plants that grow chiefly on sand or sand-mud bottom. They are most abundant in water less than 9m deep. The common types are: Eel grass (Zostera), Turtle grass (Thallasia), and Mantee grass (Syringodium).
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Seagrass Beds
Benthic communities, usually on shallow, sandy or muddy bottoms, dominated by grasslike marine plants.
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Sediment
Loose fragments of rocks, minerals or organic material which are transported from their source for varying distances and deposited by air, wind, ice and water. Other sediments are precipitated from the overlying water or form chemically, in place.
- The fine grained material deposited by water or wind.
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Sediment Transport
The main agencies by which sedimentary materials are moved are: gravity (gravity transport); running water (rivers and streams); ice (glaciers); wind; the sea (currents and longshore drift). Running water and wind are the most widespread transporting agents. In both cases, three mechanisms operate, although the particle size of the transported material involved is very different, owing to the differences in density and viscosity of air and water. The three processes are: rolling or traction, in which the particle moves along the bed but is too heavy to be lifted from it; saltation; and suspension, in which particles remain permanently above the bed, sustained there by the turbulent flow of the air or water.
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Shoreface
The narrow zone seaward from the low tide shoreline, covered by water, over which the beach sands and gravels actively oscillate with changing wave conditions.
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Shoreline Setback
see Building Setback.
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Stakeholders
Individuals, groups of individuals and non-governmental and government entities that have either a direct or indirect interest or claim which will, or may, be affected by a particular decision or policy.
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Surf Zone
The zone of wave action extending from the water line (which varies with tide, surge, set-up, etc.) out to the most seaward point of the zone (breaker zone) at which waves approaching the coastline commence breaking, typically in water depths of between 5 to 10m.
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Undercutting
Erosion of material at the foot of a cliff or bank, e.g. a sea cliff, or river bank on the outside of a meander. Ultimately, the overhang collapses, and the process is repeated.
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Undertow
A current below water surface flowing seaward; the receding water below the surface from waves breaking on a shelving beach. Actually undertow is largely mythical. As the backwash of each wave flows down the beach, a current is formed which flows seaward. However, it is a periodic phenomenon. The most common phenomena expressed as "undertow" are actually rip currents.
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Urban Runoff
The input of hydrocarbons, heavy metals, pesticides, and other chemicals to the nearshore marine environment from densely populated areas.
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Wharf
A structure built on the shore of a harbor, river, or canal, so that vessels may lie alongside to receive and discharge cargo and passengers
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Wind Rose
Diagram showing the long-term distribution of wind speed and direction.
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Zooxanthellae
Unicellular, symbiotic algae living within coral polyps that produce food for their hosts by photosynthesis and help efficiently recycle low-levels of nutrients.
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 Glossary Index
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