Glossary Coastal Inundation
Glossary
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Adaptation
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Adjustment in natural or human systems in response to current natural hazards and actual or expected climate change impacts. Actions taken to help communities and ecosystems moderate, cope with, or take advantage of actual or expected changes in weather and climate conditions. (Modified from IPCC, 2007)
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Advanced Circulation (ADCIRC)
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ADCIRC is a system of computer programs for solving time-dependent, free-surface circulation and transport problems in two and three dimensions. These programs utilize the finite element method in space allowing the use of highly flexible, unstructured grids. Typical ADCIRC applications have included (i) modeling tides and wind driven circulation, (ii) analysis of hurricane storm surge and flooding, (iii) dredging feasibility and material disposal studies, (iv) larval transport studies, and (v) nearshore marine operations. (See www.adcirc.org.)
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Bathtub mapping of sea level rise
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Sea level rise mapping using a single value of water level rise in all locations. This method does not take into account storm tide, waves, or wind.
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Bathymetry
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The measurement of depths of water in oceans, seas, and lakes; also the information derived from such measurements.
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Coastal erosion
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The wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage. A combination of episodic inundation events and relative sea level rise will serve to accelerate coastal erosion.
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Community-based social marketing
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A field focused specifically on changing peoples' behaviors and actions using a variety of tools such as prompts, incentives, commitments, social norms, and vivid communication.
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Datum
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Any position or element in relation to which others are determined, as datum point, datum line, datum plane. (See www.ngs.noaa.gov/faq.shtml.)
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Datum (vertical)
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For marine applications, a base elevation used as a reference from which to reckon heights or depths. It is called a tidal datum when defined in terms of a certain phase of the tide. Tidal datums are local datums and should not be extended into areas that have differing hydrographic characteristics without substantiating measurements. So that they may be recovered when needed, such datums are referenced to fixed points known as benchmarks. (See http://co-ops.nos.noaa.gov/datum_options.html.)
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Depth rasters
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A grid that shows the depth of floodwater over an area that is typically dry.
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Digital Elevation Model
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Digital elevation models (DEMs) consist of a raster grid of regularly spaced elevation values. (See http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/DEMs)
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Exposure
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Types and amount of assets at risk.
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Geographic Information System
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A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. (See www.esri.com/what-is-gis/index.html.)
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Global sea level rise
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Caused by a change in the volume of the world's oceans due to temperature increase, deglaciation (uncovering of glaciated land because of melting of the glacier), and ice melt.
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Inland flooding
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Occurs when moderate precipitation accumulates over several days, intense precipitation falls over a short period, or a river overflows because of an ice or debris jam or dam or levee failure (NOAA, 2009). Hurricane Floyd (1999), aided by Tropical Storm Dennis (1999), caused widespread severe flooding that caused the majority of the $3 to 6 billion in damage reported after those storms.
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Inundation
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Water covering normally dry land is a condition known as inundation.
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Land cover
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Refers to the vegetation, structures, or other features that cover the land. For example, is the land covered by grass, by trees, by water, or by large buildings surrounded by a lawn? (See www.cara.psu.edu/land/lu-primer/luprimer01.asp.)
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Land use
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Refers to how land is used by humans. In other words it refers to the economic use to which land is put. For example, is the land being used for commercial purposes (stores, office buildings, apartments, etc.) or for industrial purposes (factories, assembly plants)? Or is the land being used for recreational or agricultural purposes? (See www.cara.psu.edu/land/lu-primer/luprimer01.asp.)
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Lidar
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An instrument capable of measuring distance and direction to an object by emitting timed pulses of light in a measured direction and converting to the equivalent distance the measured interval of time between when a pulse was emitted and when its echo was received Also called laser radar. When combined with a Global Positioning System (GPS), lidar technology can be used to map coastal topography faster and more thoroughly than traditional surveying methods. (See www.geoworkforce.olemiss.edu/tools/glossary_asprs/index.php.)
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Mean High Water (MHW)
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A tidal datum. The average of all the high water heights observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. (See http://tidesandcurrents.noaa.gov/publications/glossary2.pdf or http://tidesandcurrents.noaa.gov/datum_options.html.)
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Mean Lower Low Water (MLLW)
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A tidal datum. The average of the lower low water height of each tidal day observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. (See http://tidesandcurrents.noaa.gov/publications/glossary2.pdf or http://tidesandcurrents.noaa.gov/datum_options.html.)
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Metadata
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A metadata record is a file of information, usually presented as an XML document, that captures the basic characteristics of a data or information resource. It provides the who, what, when, where, why, and how of the resource. (See www.fgdc.gov/metadata.)
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National Geodetic Vertical Datum of 1929 (NGVD29)
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A fixed reference adopted as a standard geodetic datum for elevations determined by leveling. The datum was derived for surveys from a general adjustment of the first-order leveling nets of both the United States and Canada. In the adjustment, mean sea level was held fixed as observed at 21 tide stations in the United States and 5 in Canada. The geodetic datum now in use in the United States is the National Geodetic Vertical Datum. The year indicates the time of the general adjustment. The geodetic datum is fixed and does not take into account the changing stands of sea level. Because there are many variables affecting sea level, and because the geodetic datum represents a best fit over a broad area, the relationship between the geodetic datum and local mean sea level is not consistent from one location to another in either time or space. For this reason, the National Geodetic Vertical Datum should not be confused with mean sea level. NGVD (1929) has been superseded for use by NAVD88. (See www.ngs.noaa.gov/faq.shtml.)
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North American Vertical Datum of 1988 (NAVD88)
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A fixed reference for elevations determined by geodetic leveling. The datum was derived from a general adjustment of the first-order terrestrial leveling nets of the United States, Canada, and Mexico. In the adjustment, only the height of the primary tidal bench mark, referenced to the International Great Lakes Datum of 1985 (IGLD 85) Local mean sea level height value, at Father Point, Rimouski, Quebec, Canada was held fixed, thus providing minimum constraint. NAVD 88 and IGLD 85 are identical. However, NAVD 88 bench mark values are given in Helmert orthometric height units while IGLD 85 values are in dynamic heights. See International Great Lakes Datum of 1985, National Geodetic Vertical Datum of 1929, and geopotential difference. (See www.ngs.noaa.gov/faq.shtml.)
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Point classification
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In an elevation data set, points can be categorized according to the surface the point strikes. For example, if the laser in a lidar survey reaches the ground, this point could be categorized as "bare earth," but if the laser is returned from the surface of a building, this point could be categorized as "first return." In this way, the ground surface and the first return surface can be separated.
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Relative Sea Level Rise
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Occurs where there is a local increase in the level of the ocean relative to the land, which might be due to ocean rise or land subsidence.
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Resilience
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The capacity of a system, community, or society potentially exposed to hazards to adapt, by resisting or changing, in order to reach and maintain an acceptable level of functioning and structure. This is determined by the degree to which the social system is capable of organizing itself to increase its capacity for learning from past disasters for better future protection and to improve risk reduction measures. (SDR, 2005)
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Risk
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The probability of harmful consequences or expected losses (death and injury, losses of property and livelihood, economic disruption, or environmental damage) resulting from interactions between natural or human-induced hazards and vulnerable conditions. (SDR, 2005)
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Scale
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The ratio of a specified distance, or the average ratio of specified distances, on a map to the corresponding distance or distances on the ellipsoid used in making the map (i.e., used in the map projection). The U.S. Geological Survey classifies maps with scales of 1:20,000 to 1:25,000 as medium-scale maps; maps at scales of 1:50,000 to 1:100,000 as intermediate-scale maps; and maps at scales of 1:250,000 or less as small-scale maps. (See www.geoworkforce.olemiss.edu/tools/glossary_asprs/index.php.)
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Sea, Lake, and Overland Surges from Hurricanes (SLOSH)
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A computerized model run by the National Hurricane Center (NHC) to estimate storm surge heights and winds resulting from historical, hypothetical, or predicted hurricanes by taking into account pressure, size, forward speed, track, and winds. (See www.nhc.noaa.gov/HAW2/english/surge/slosh.shtml.)
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Shallow coastal flooding
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The inundation of land areas along the coast caused by higher than average high tide and worsened by heavy rainfall and onshore winds (i.e., wind blowing landward from the ocean). Places like Charleston, South Carolina, and Savannah, Georgia, experience impacts from shallow coastal flooding several times a year because of coastal development and lower elevation.
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Spatial resolution
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Also known as horizontal resolution, can be expressed as the size of pixels or cell size of a grid. The coarser the resolution, the more ground area that is represented by a single pixel or elevation. For example, national data have a very low resolution, and community-specific data require a very high resolution.
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Storm surge
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Water that is pushed toward the shore by the force of the winds swirling around the storm. This advancing surge combines with the normal tides to create the hurricane storm tide, which can increase the mean water level 15 feet or more. (See www.nhc.noaa.gov/HAW2/english/storm_surge.shtml.)
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Subsidence
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Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. Subsidence is a global problem, and in the United States, more than 17,000 square miles in 45 states, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence.
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Surface generation
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Creating an elevation surface from point data.
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Tsunami
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A series of large waves generated by an abrupt disturbance of the sea surface (e.g., from an earthquake or landslide) (NOAA, 2009).
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Vertical reference
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see datum (vertical)
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Vulnerability
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Susceptibility of people, property, and resources to negative impacts from hazard events