Terminology Services

Coastal Sensitivity to Sea-level Rise Glossary and Acronyms

Description:

Glossary, acronyms, and abbreviations of technical and scientific terms used throughout the Coastal Sensitivity to Sea-Level Rise Report

Publishing Organization:

Office of Air and Radiation/Office of Atmospheric Protection/Climate Change Division

Last Update:

January 15, 2009

Program Site:

https://www.epa.gov/cre/coastal-adaptation-toolkit#impacts

Terms & Acronyms

Search Terms

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	Term
	100-year flood	Definition: The standard used by the National Flood Insurance Program (NFIP) for floodplain management purposes and to determine the need for flood insurance. A structure located within a special flood hazard area shown on an NFIP map has a 26 percent chance of suffering flood damage during the term of a 30-year mortgage.
	access, lateral	Definition: The right to walk or otherwise move along a shoreline, once someone has reached the shore.
	access, perpendicular	Definition: A legally permissible means of reaching the shore from dry land.
	access point	Definition: A place where anyone may legally gain access to the shore; usually a park, the end of a public street, or a public path; a place where perpendicular access (see access, perpendicular) is provided.
	accretion	Definition: The accumulation of a sedimentary deposit that increases the size of a land area. This increase may be either lateral or vertical.
	Advisory Base Flood Elevations	Acronym: ABFE
	Albemarle-Pamlico	Acronym: A-P
	Areas of Environmental Concern	Acronym: AEC
	armoring	Definition: The placement of fixed engineering structures, typically rock or concrete, on or along the shoreline to mitigate the effects of coastal erosion and protect infrastructure; such structures include seawalls, revetments, bulkheads, and riprap.
	Association of State Floodplain Managers	Acronym: ASFPM
	Atlantic margin
	avulsion	Definition: A sudden cutting off or separation of land by a flood or by an abrupt change in the course of a stream; as by a stream breaking through a meander or a sudden change in current whereby a stream deserts its old channel for a new one; or rapid erosion of the shore by waves during a storm.
	barrier island	Definition: A long, narrow coastal sandy island that is above high tide and parallel to the shore, and that commonly has dunes, vegetated zones, and swampy terraces extending landward from the beach.
	barrier island rollover	Definition: The landward migration or landward transgression of a barrier island, accomplished primarily over decadal or longer time scales through the process of storm overwash, periodic inlet formation, and wind-blown transport of sand.
	barrier migration	Definition: The movement of an entire barrier island or barrier spit in response to sea-level rise, changes in sediment supply, storm surges or waves, or some combination of these factors.
	barrier spit	Definition: A barrier island that is connected at one end to the mainland bathymetry the measurement of ocean depths and the mapping of the topography of the seafloor.
	base flood elevation	Acronym: BFE
	bathymetry	Definition: The measurement of ocean depths and the mapping of the topography of the seafloor.
	beach	Definition: The unconsolidated material that covers a gently sloping zone extending landward from the low water line to the place where there is a definite change in material or physiographic form (such as a cliff), or to the line of permanent vegetation (usually the effective limit of the highest storm waves).
	beach nourishment	Definition: The addition of sand, often dredged from offshore, to an eroding shoreline to enlarge or create a beach area, offering both temporary shore protection and recreational opportunities.
	berm	Definition: A commonly occurring, low, impermanent, nearly horizontal ledge or narrow terrace on the backshore of a beach, formed of material thrown up and deposited by storm waves.
	bluff	Definition: A high bank or bold headland with a broad, precipitous, sometimes rounded cliff face overlooking a plain or body of water.
	breach	Definition: (n.) a channel through a barrier spit or island typically formed by storm waves, tidal action, or river flow; breaches commonly occur during high storm surge cause by a hurricane or extratropical storm; (v.) to cut a deep opening in a landform.
	breakwater	Definition: An offshore structure (such as a wall or jetty) that, by breaking the force of the waves, protects a harbor, anchorage, beach or shore area.
	bulkhead	Definition: A structure or partition to retain or prevent sliding of the land; a secondary purpose is to protect uplands against damage from wave action.
	Climate Change Science Program	Acronym: CCSP
	Coastal Area Management Act	Acronym: CAMA
	Coastal Barrier Resources Act	Acronym: CBRA
	Coastal Facility Review Act	Acronym: CAFRA
	coastal plain	Definition: Any lowland area bordering a sea or ocean, extending inland to the nearest elevated land, and sloping very gently seaward.
	Coastal Resources Commission	Acronym: CRC
	Coastal Vulnerability Index	Acronym: CVI
	coastal zone	Definition: The area extending from the ocean inland across the region directly influenced by marine processes.
	Coastal Zone Management	Acronym: CZM
	Coastal Zone Management Act	Acronym: CZMA
	coastline	Definition: The line that forms the boundary between the coast and the shore or the line that forms the boundary between the land and the water.
	Comprehensive Coastal Management Plan	Acronym: CCMP
	continental margin	Definition: The region of the sea floor between the shoreline and the deep abyssal ocean, see margin, active and margin, passive.
	continental shelf	Definition: The gently sloping underwater region at the edge of the continent that extends from the beach to where the steep continental slope begins, usually at depths greater than 300 feet.
	continuously operating reference stations	Acronym: CORS
	contour interval	Definition: The difference in elevations of adjacent contours on a topographic map.
	Cooperative Technical Partnership	Acronym: CTP
	current	Definition: The horizontal movement patterns in bodies of water; in coastal areas, currents are influenced by a combination of tidal (flood and ebb) and nontidal (wind-driven, river flow) forces.
	datum	Definition: A quantity, or a set of quantities, that serves as a basis for the calculation of other quantities; in surveying and mapping, a datum is a point, line or surface used as a reference in measuring locations or elevations.
	Delaware Division of Fish and Wildlife	Acronym: DDFW
	delta	Definition: A low relief landform composed of sediments deposited at the mouth of a river that commonly forms a triangular or fan-shaped plain of considerable area crossed by many channels from the main river; forms as the result of accumulation of sediment supplied by the river in such quantity that it is not removed by tidal or wave-driven currents.
	Department of Environmental Conservation	Acronym: DEC
	deposition	Definition: The laying, placing, or throwing down of any material; typically refers to sediment.
	depth of closure	Definition: A theoretical depth below which sediment exchange between the nearshore (beach and shoreface) and the continental shelf is deemed to be negligible.
	digital elevation model	Definition: The digital representation of the ground surface or terrain using a set of elevation data. Acronym: DEM
	digital flood insurance rate maps	Acronym: DFIRM
	dike	Definition: A wall generally of earthen materials designed to prevent the permanent submergence of lands below sea level, tidal flooding of lands between sea level and spring high water, or storm-surge flooding of the coastal floodplain.
	discount rate	Definition: An assumed interest rate or rate of return used to calculate the present value of a future payment; in mathematical terms, the present value of receiving $1 Y years hence is 1/(1-r)Y, where r is the discount rate.
	downdrift	Definition: The location of one section or feature along the coast in relation to another; often used to refer to the direction of net longshore sediment transport between two or more locations (i.e., downstream).
	dredge and fill	Definition: An engineering process by which channels are dredged through wetlands or uplands to allow small boat navigation, and dredge spoil is placed on the adjacent land area to raise the land high enough to allow development; sometimes referred to as "lagoon development" or "canal estates"; used extensively before the 1970s.
	dune	Definition: A low mound, ridge, bank, or hill of loose, wind-blown material such as sand; capable of movement from place to place but typically retaining a characteristic shape; may be either bare or covered with vegetation.
	ebb current	Definition: The tidal current associated with the decrease in height of the tide, generally moving seaward or down a tidal river or estuary, see also flood current.
	ebb tide delta	Definition: A large sand shoal commonly deposited at the mouths of tidal inlets formed by ebbing tidal currents and modified in shape by waves, compare with flood tide delta.
	erosion	Definition: The mechanical removal of sedimentary material by gravity, running water, moving ice, or wind; in the context of coastal settings erosion refers to the landward retreat of a shoreline indicator such as the water line, the berm crest, or the vegetation line; the loss occurs when sediments are entrained into the water column and transported from the source.
	erosion-based setback	Definition: A setback equal to an estimated annual erosion rate multiplied by a number of years set by statute or regulation (e.g.,30 years).
	estuary	Definition: A semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with freshwater from land drainage; an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, usually being divisible into three sectors; (a) a marine or lower estuary, in free connection with the open sea; (b) a middle estuary subject to strong salt and freshwater mixing; and (c) an upper or fluvial estuary, characterized by fresh water but subject to daily tidal action; limits between these sectors are variable, and subject to constant changes in the river discharge.
	extratropical storm	Definition: A cyclonic weather system, occuring in the middle or high latitudes (e.g., poleward of the tropics) that is generated by colliding airmasses; such weather systems often spawn large storms that occurr between late fall and early spring.
	Federal Emergency Management Agency	Acronym: FEMA
	Federal Geographic Data Committee	Acronym: FGDC
	fetch	Definition: The area of the open ocean where the winds blow over with constant speed and direction, generating waves.
	flood current	Definition: The tidal current associated with the increase in height of the tide or the incoming tide, generally moving landward or up into a tidal river or estuary, see also ebb current.
	Flood Insurance Rate Maps	Acronym: FIRM
	Flood Insurance Studies	Acronym: FIS
	flood tide delta	Definition: A large sand shoal commonly deposited on the landward side of a tidal inlet formed by flooding tidal currents, compare with ebb tide delta.
	flooding	Definition: The temporary submergence of land that is normally dry, often due to periodic events such as storms, see also inundation.
	floodproofing	Definition: A set of techniques that are intended to limit the amount of damage that will occur to a building and/or its contents during a flood (see also floodproofing, dry and floodproofing, wet).
	floodproofing, dry	Definition: A floodproofing technique in which modifications are made to allow floodwaters inside a building while ensuring that there is minimal damage to either the structure or its contents.
	floodproofing, wet	Definition: A floodproofing technique in which a building is sealed such that floodwaters cannot get inside the structure.
	forcing	Definition: To hasten the rate of progress or growth; in this report, forcing generally refers to climate change factors that act to alter a particular physical, chemical, or biological system (e.g., changes in climate such as greenhouse gas concentration, temperature, sea level, or storm characteristics).
	General Accountability Office (2007)	Acronym: GAO
	General Accounting Office (1982)	Acronym: GAO
	geographic information system	Acronym: GIS
	geologic framework	Definition: The underlying geological setting, structure, and lithology (rock/sediment type) in a given area.
	geomorphic
	geomorphology	Definition: The external structure, form, and arrangement of rocks or sediments in relation to the development of the surface of the Earth.
	Global Earth Observation System of Systems	Acronym: GEOSS
	Global Positioning System	Acronym: GPS
	global sea-level rise	Definition: The worldwide average rise in mean sea level; may be due to a number of different causes, such as the thermal expansion of sea water and the addition of water to the oceans from the melting of glaciers, ice caps, and ice sheets; contrast with relative sea-level rise.
	greatest conservation need	Acronym: GCN
	groin	Definition: An engineering structure oriented perpendicular to the coast, used to accumulate littoral sand by interrupting longshore transport processes; often constructed of concrete, timbers, steel, or rock.
	high marsh	Definition: The part of a marsh that lies between the low marsh and the marsh's upland border; this area can be expansive, extending hundreds of yards inland from the low marsh area; soils here are mostly saturated but only flooded during higher-than-average astronomical tides (see tides and tides, astronomical).
	high water mark	Definition: A demarcation between the publicly owned land along the water and privately owned land which has legal implications regarding public access to the shore; generally based on mean high water, the definition varies by state; along beaches with significant waves, it may be based on the line of vegetation, the water mark caused by wave runup, surveys of the elevation of mean high water, or other procedures.
	highest observed water levels	Acronym: HOWL
	hydrodynamic climate	Definition: The characteristics of nearshore or continental shelf currents in an area that typically result from waves, tides, and weather systems.
	inlet	Definition: A small, narrow opening, recess, indentation, or other entrance into a coastline or shore of a lake or river through which water penetrates landward; commonly refers to a waterway between two barrier islands that connects the sea and a lagoon.
	Integrated Ocean Observing System	Acronym: IOOS
	intensely developed area	Acronym: IDA
	Intergovernmental Panel on Climate Change	Acronym: IPCC
	Intergovernmental Panel on Climate Change Coastal Zone Management Subgroup	Acronym: IPCC CZMS
	intertidal	Definition: See littoral
	inundation	Definition: The submergence of land by water, particularly in a coastal setting, see also flooding.
	jetty	Definition: An engineering structure built at the mouth of a river or tidal inlet to help stabilize a channel for navigation; designed to prevent shoaling of a channel by littoral materials and to direct and confine the stream or tidal flow.
	lagoon	Definition: A shallow coastal body of seawater that is separated from the open ocean by a barrier or coral reef; the term is commonly used to define the shore-parallel body of water behind a barrier island or barrier spit.
	levee	Definition: A wall, generally of earthen materials, designed to prevent the flooding of a river after periods of exceptional rainfall.
	Light Detection And Ranging	Definition: Light Detection And Ranging is a remote sensing instrument that uses laser light pulses to measure the elevation of the land surface with a high degree of accuracy and precision. Acronym: lidar
	limited development area	Acronym: LDA
	lithospheric	Definition: Of or pertaining to the solid portion of the Earth, including the crust and part of the upper mantle; the region of the Earth that is studied in plate tectonics.
	littoral	Definition: The zone between high and low tide in coastal waters or the shoreline of a freshwater lake.
	littoral cell	Definition: A section of coast for which sediment transport processes can be isolated from the adjacent coast; within each littoral cell, a sediment budget can be defined that describes sinks, sources, and internal fluxes.
	littoral transport	Definition: The movement of sediment littoral drift in the littoral zone by waves and currents; includes movement both parallel and perpendicular to the shore.
	littoral zone	Definition: The region of the shore that occurs between the high and low water marks.
	living shoreline	Definition: A shore protection concept where some or all of the environmental characteristics of a natural shoreline are retained as the position of the shore changes.
	local mean sea level	Acronym: LMSL
	long-lived infrastructure	Definition: Infrastructure that is likely to be in service for a long time, and therefore may benefit from consideration of sea-level rise and shoreline changes in planning and/or maintenance.
	longshore current	Definition: An ocean current in the littoral zone that moves parallel to the shoreline; produced by waves approaching at an angle to the shoreline.
	longshore transport	Definition: The movement of sediment parallel to the shoreline in the surf zone by wave suspension and the longshore current.
	low marsh	Definition: The seaward edge of a salt marsh, usually a narrow band along a creek or ditch which is flooded at every high tide and exposed at low tide (see also high marsh).
	margin, active	Definition: A continental margin located where the edges of lithospheric plates are colliding, resulting in tectonic activity such as volcanoes and earthquakes; also called a "Pacific margin" after the Pacific Ocean where such margins are common; compare with margin, passive.
	margin, passive	Definition: A continental margin located in the middle of a lithospheric plate (see lithosphere) where tectonic activity is minimal; also called an "Atlantic margin" after the Atlantic Ocean where such margins are common; compare with margin, active.
	marsh	Definition: A frequently or continually inundated wetland characterized by herbaceous vegetation adapted to saturated soil conditions (see also salt marsh).
	mean high water	Definition: A tidal datum; the average height of high water levels observed over a 19-year period. Acronym: MHW
	mean high water mark
	mean higher high water	Definition: The average of the higher high water height of each tidal day observed over the national tidal datum epoch. (see national tidal datum epoch) Acronym: MHHW
	Mean Low Water	Acronym: MLW
	Mean Lower Low Water	Acronym: MLLW
	mean sea level	Definition: The "still water level" (i.e., the level of the sea with high frequency motions such as wind waves averaged out); averaged over a period of time such as a month or a year, such that periodic changes in sea level (e.g., due to the tides) are also averaged out; the values of MSL are measured with respect to the level of marks on land (called benchmarks). Acronym: MSL
	metadata	Definition: A file of information which captures the basic characteristics of a data or information resource; representing the who, what, when, where, why and how of the data resource; geospatial metadata are used to document geographic digital resources such as Geographic Information System (GIS) files, geospatial databases, and earth imagery.
	moral hazard	Definition: A circumstance in which insurance, lending practices, or subsidies designed to protect against a specified hazard induce people to take measures that increase the risk of that hazard.
	mudflat	Definition: A level area of fine silt and clay along a shore alternately covered and uncovered by the tide or covered by shallow water.
	National Academy of Sciences	Acronym: NAS
	National Climatic Data Center	Acronym: NCDC
	National Digital Elevation Program	Acronym: NDEP
	National Elevation Dataset	Acronym: NED
	National Estuarine Research Reserve System	Acronym: NERRS
	National Flood Insurance Program	Acronym: NFIP
	National Geodetic Vertical Datum	Acronym: NGVD
	national geodetic vertical datum of 1929	Definition: A fixed reference adopted as a standard geodetic datum for elevations; it was determined by leveling networks across the United States and sea-level measurements at 26 coastal tide stations; this reference is now superseded by the North American vertical datum of 1988 (NAVD88). Acronym: NGVD29
	National Heritage Program	Acronym: NHP
	National Highway System	Acronym: NHS
	National Land Cover Data	Acronym: NLCD
	National Map Accuracy Standards	Acronym: NMAS
	National Oceanic and Atmospheric Administration	Acronym: NOAA
	National Park Service	Acronym: NPS
	National Research Council	Acronym: NRC
	National Standard for Spatial Data Accuracy	Acronym: NSSDA
	national tidal datum epoch	Definition: The latest 19-year time period over which NOAA has computed and published official tidal datums and local mean sea-level elevations from tide station records; currently, the latest NTDE is 1983-2001. Acronym: NTDE
	National Weather Service	Acronym: NWS
	National Wildlife Refuge	Acronym: NWR
	The Nature Conservancy	Acronym: TNC
	nearshore zone	Definition: The zone extending from the shoreline seaward to a short, but indefinite distance offshore, typically confined to depths less than 5 meters (16.5 feet).
	No Adverse Impact	Acronym: NAI
	nontidal wetlands	Definition: Wetlands that are not exposed to the periodic change in water level that occurs due to astronomical tides (see tides and tides, astronomical).
	nor'easter	Definition: The name given to the strong northeasterly winds associated with extra-tropical cyclones that occur along East Coast of the United States and Canada; these storms often cause beach erosion and structural damage; wind gusts associated with these storms can approach and sometimes exceed hurricane force in intensity.
	North American Vertical Datum	Acronym: NAVD
	North American vertical datum of 1988	Definition: A fixed reference for elevations determined by geodetic leveling, derived from a general adjustment of the first-order terrestrial leveling networks of the United States, Canada, and Mexico; NAVD88 supersedes NGVD29. Acronym: NAVD88
	northeaster
	ordinary high water mark
	outwash plain	Definition: A braided stream deposit beyond the margin of a glacier; it is formed from meltwater flowing away from the glacier, depositing mostly sand and fine gravel in a broad plain.
	overwash	Definition: The sediment that is transported from the beach across a barrier and is deposited in an apron-like accumulation along the backside of the barrier; overwash usually occurs during storms when waves break through the frontal dune ridge and flow landward toward the marsh or lagoon.
	Pacific margin
	Physical Oceanographic RealTime System	Acronym: PORTS
	pocket beach	Definition: A small, narrow beach formed between two littoral obstacles, such as between rocky headlands or promontories that occur at the shore.
	Public Trust Doctrine	Definition: A legal principle derived from English Common Law which holds that the waters of a state are a public resource owned by and available to all citizens, and that these public property rights are not invalidated by private ownership of the underlying or adjacent land. In most states, the public trust rights include the land below mean high water. In five low water states, the public has an access right to intertidal land solely for the purpose of hunting, fishing, fowling, and navigation.
	rebound	Definition: The uplift of land following deglaciation due to the mass of ice being removed from the land surface.
	relative sea-level rise	Definition: The rise in sea level measured with respect to a specified vertical datum relative to the land, which may also be changing elevation over time; typically measured using a tide gauge; compare with global sea-level rise.
	resource conservation area	Acronym: RCA
	resource protection area	Acronym: RPA
	retreat	Definition: One of three possible responses to sea-level rise, which involves adapting to shoreline change rather than attempting to prevent it, generally by either preventing construction in a vulnerable area or removing structures already in the vulnerable area; the other two responses are various methods of shore protection or floodproofing.
	revetment	Definition: A sloped facing of stone, concrete, etc., built to protect a scarp, embankment, or shore structure against erosion by wave action or currents.
	rip current	Definition: A strong, narrow current of surface water that flows seaward through the surf into deeper water.
	riprap	Definition: Loose boulders placed on or along the shoreline as a form of armoring.
	river diversion	Definition: A set of engineering approaches used to redirect the flow of river water from its natural course for a range of purposes; commonly used to bypass water during dam construction, for flood control, for navigation, or for wetland and floodplain restoration.
	rolling easement	Definition 1: 1. An interest in land (by title or interpretation of the Public Trust Doctrine) in which a property owner's interest in preventing real estate from eroding or being submerged yields to the public or environmental interest in allowing wetlands or beaches to migrate inland, usually by prohibiting shore protection. Definition 2: 2. A government regulation that preserves the environment and/or the public's access along the coast as shorelines retreat by requiring the removal of structures once they are inland of a defined high water mark (e.g. the dune vegetation line or mean high water).
	rollover	Definition: (see barrier island rollover)
	root mean square error	Definition: A measure of statistical error calculated as the square root of the sum of squared errors, where error is the difference between an estimate and the actual value; if the mean error is zero, it also equals the standard deviation of the error. Acronym: RMSE
	salt marsh	Definition: A grassland containing salt-tolerant vegetation established on sediments bordering saline water bodies where water level fluctuates either tidally or nontidally (see also marsh).
	saltwater intrusion	Definition: Displacement of fresh or ground water by the advance of salt water due to its greater density, usually in coastal and estuarine areas.
	seawall	Definition: A structure, often concrete or stone, built along a portion of a coast to prevent erosion and other damage by wave action; often it retains earth against its shoreward face; a seawall is typically more massive than (and therefore capable of resisting greater wave forces than) a bulkhead.
	sediment(s)	Definition: Solid materials or fragments that originate from the break up of rock and are transported by air, water or ice, or that accumulate by other natural agents such as chemical precipitation or biological secretions; solid materials that have settled from being suspended, as in moving water or air.
	sediment supply	Definition: The abundance or lack of sediment in a coastal system that is available to contribute to the maintenance or evolution of coastal landforms including both exposed features such as beaches and barrier islands, and underwater features such as the seabed.
	setback	Definition: The requirement that construction be located a minimum distance inland from tidal wetlands, tidal water, the primary dune line, or some other definition of the shore.
	shoal	Definition: A relatively shallow place in a stream, lake, sea, or other body of water; a submerged ridge, bank, or bar consisting of or covered by sand.
	shore	Definition: The narrow strip of land immediately bordering any body of water, especially a sea or large lake; the zone over which the ground is alternately exposed and covered by the tides or waves, or the zone between high and low water.
	shore protection	Definition: A range of activities that focus on protecting land from inundation, erosion, or storm-induced flooding through the construction of various structures such as jetties, groins, or seawalls, or the addition of sediments to the shore (for example, beach nourishment).
	shoreface	Definition: The narrow relatively steep surface that extends seaward from the beach, often to a depth of 30 to 60 feet, at which point the slope flattens and merges with the continental shelf.
	shoreline	Definition: The intersection of a specified plane of water with the shore or beach; on National Ocean Service nautical charts and surveys, the line representing the shoreline approximates the mean high water line.
	shoreline armoring	Definition: A method of shore protection that prevents shore erosion through the use of hardened structures such as seawalls, bulkheads, and revetments; see also armoring.
	Shuttle Radar Topography Mission	Acronym: SRTM
	significant wave height	Definition: the average height of the highest one-third of waves in a given area.
	soft shore protection	Definition: A method of shore protection that prevents shore erosion through the use of materials similar to those already found in a given location, such as adding sand to an eroding beach or planting vegetation whose roots will retain soils along the shore.
	Special Flood Hazard Area	Acronym: SFHA
	spit	Definition: A fingerlike extension of the beach that was formed by longshore sediment transport; typically, it is a curved or hook-like sandbar extending into an inlet.
	spring high water	Definition: The average height of the high waters during the semimonthly times of spring tides (occurs at the full and new moons).
	still water flood level	Acronym: SWFL
	storm surge	Definition: An abnormal rise in sea level accompanying a hurricane or other intense storm, whose height is the difference between the observed level of the sea surface and the level that would have occurred in the absence of the cyclone.
	submerged aquatic vegetation	Acronym: SAV
	submergence	Definition: A rise of the water level relative to the land, so that areas that were formerly dry land become inundated; it is the result either of the sinking of the land or a net rise in sea level.
	subsidence	Definition: The downward settling of the Earth's crust relative to its surroundings.
	surf zone	Definition: The zone of the nearshore region extending from the point offshore where waves break to the landward limit of wave run-up, as on a beach.
	taxa	Definition: (Plural of taxon) A general term applied to any taxonomic element, population, or group irrespective of its classification level.
	threshold	Definition: in climate change studies, a threshold generally refers to the point at which the climate system begins to change in a marked way because of increased forcing; crossing a climate threshold triggers a transition to a new state of the system at a generally faster rate.
	tidal currents	Definition: The horizontal movement of ocean water caused by gravitational interactions between the Sun, Moon and Earth; part of the same general movement of the sea that is manifested in the vertical rise and fall called the tide; see also ebb current and flood current.
	tidal datum	Definition: A baseline elevation used as a vertical point of reference from which heights or depths can be reckoned; called a tidal datum when defined in terms of a certain phase of the tide.
	tidal freshwater marsh	Definition: A marsh along a river or estuary, close enough to the coastline to experience significant tides by nonsaline water; the vegetation is often similar to a nontidal freshwater marsh.
	tidal inlet	Definition: An opening in the shoreline through which water penetrates the land, thereby providing a connection between the ocean and bays, lagoons, and marsh and tidal creek systems; the main channel of a tidal inlet is maintained by tidal currents.
	tidal range	Definition: The vertical difference between normal high and low tides often computed as the elevation difference between mean high water and mean low water; spring tide range is the elevation difference between spring high water and spring low water.
	tidal wetlands	Definition: Those wetlands that are exposed to the periodic rise and fall of the astronomical tides (see tides and tides, astronomical).
	tide-dominated	Definition: A barrier or coastal area where the morphology is primarily a product of tidal processes.
	tide gauge	Definition: The geographic location where tidal observations are conducted; consisting of a water level sensor, data collection and transmission equipment, and local benchmarks that are routinely surveyed into the sensors.
	tide(s)	Definition: The alternating rise and fall of the surface of the ocean and connected waters, such as estuaries and gulfs, that results from the gravitational forces of the Moon and Sun; also called astronomical tides (see tides, astronomical).
	tidelands	Definition: Those lands that are flooded during times of high water, and are hence available to the public under the Public Trust Doctrine.
	tides, astronomical	Definition: The alternating rise and fall of the ocean surface and connected waters, such as estuaries and gulfs, that result from the gravitational forces of the Moon and Sun.
	tipping point	Definition: A critical point in the evolution of a system that leads to new and potentially irreversible effects at a rate that can either be much faster or much slower than forcing.
	transgression	Definition: The spread or extension of the sea over land areas, and the consequent evidence of such advance; also, any change such as a rise in sea level that brings offshore deep-water environments to areas formerly occupied by nearshore, shallow-water environments or that shifts the boundary between marine and nonmarine deposition away from deep water regions.
	United States Army Corps of Engineers	Acronym: USACE
	United States Department of Transportation	Acronym: US DOT
	United States Environmental Protection Agency	Acronym: U.S. EPA
	United States Fish and Wildlife Service	Acronym: USFWS
	United States Geological Survey	Acronym: USGS
	updrift	Definition: Refers to the location of one section or feature along the coast in relation to another; often used to refer to the direction of net longshore sediment transport between two or more locations (i.e., upstream).
	V Zone	Definition: Areas where wave action and/or high velocity water can cause damage in the 100-year flood; see also A Zone.
	Virginia Public Beach Board	Acronym: VA PBB
	Waterfront Revitalization and Coastal Resources Act	Acronym: WRCRA
	wave-dominated	Definition: A barrier or coastal area where the geomorphology is primarily a product of wave processes.
	wave run-up	Definition: The upper levels reached by a wave on a beach or coastal structure, relative to still-water level.
	waves	Definition: Regular or irregular disturbances in or on the surface of a water body that form characteristic shapes and movement patterns and a range of sizes; for the purposes of this report, waves are usually generated by the wind (see fetch) and occur along the coast or in an estuary.
	wetland accretion	Definition: A process by which the surface of wetlands increases in elevation; see also accretion.
	wetland migration	Definition: A process by which tidal wetlands adjust to rising sea level by advancing inland into areas previously above the ebb and flow of the tides.
	wetlands	Definition: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soils; wetlands generally include swamps, marshes, bogs, and similar areas.
	A Zone	Definition: Areas inundated in a 100-year storm event that experience conditions of less severity than conditions experienced in V Zones.

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