- Sektör: Government
- Number of terms: 5261
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The United States Army Corps of Engineers is a federal agency with a mission to provide vital public engineering services in peace and war to strengthen the nation's security, energize the economy, and reduce risks from disasters. It is also a major U.S. Army organization employing some 38,000 ...
The average height of the low waters 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 semidiurnal or mixed. Only lower low water heights are included in the average where the type of tide is diurnal. So determined, mean low water in the latter case is the same as mean lower low water.
Industry:Engineering
The square root of the ratio of the distance between adjacent orthogonals in deep water to their distance apart in shallow water at a selected point. When multiplied by the shoaling factor and a factor for friction and percolation, this becomes the wave height coefficient or the ratio of the refracted wave height at any point to the deepwater wave height. Also, the square root of the energy coefficient.
Industry:Engineering
A beach that has either natural or engineered sand retention and that can be stable through the continued supply of natural sediment sources, without any mechanical nourishment over a long period. Subsets include:
Natural or Geomorphically Self-sustaining Beaches: self-sustaining naturally without the construction of retaining structures and with no continued mechanical sand nourishment.
Anthropogenically Self-sustaining Beaches: self-sustaining by the construction of retaining structure(s) with or without initial beach fill but with no continued mechanical sand nourishment.
Industry:Engineering
The invasion of a large area of land by the sea in a relatively short space of time (geologically speaking). Although the observable result of a marine transgression may suggest an almost ‘instantaneous’ process, it is probable that the time taken is in reality is thousands or millions of years. The plane of marine transgression is a plane of unconformity.
Industry:Engineering
A hypohurricane that might result from the most severe combination of hurricane parameters that is considered reasonably possible in the region involved, if the hurricane should approach the point under study along a critical path and at optimum rate of movement. This estimate is substantially more severe than the SPH criteria.
Industry:Engineering
(1) A natural or artificial waterway of perceptible extent which either periodically or continuously contains moving water, or which forms a connecting link between two bodies of water.
(2) The part of a body of water deep enough to be used for navigation through an area otherwise too shallow for navigation. (3) A large strait, as the English Channel. (4) The deepest part of a stream, bay, or strait through which the main volume or current of water flows.
Industry:Engineering
The water depth beyond which repetitive profile or topographic surveys (collected over several years) do not detect vertical sea bed changes, generally considered the seaward limit of littoral transport. The depth can be determined from repeated cross-shore profile surveys or estimated using formulas based on wave statistics. Note that this does not imply the lack of sediment motion beyond this depth.
Industry:Engineering
(1) A comparatively high promontory with either a cliff or steep face extending out into a body of water, such as a sea or lake. An unnamed head is usually called a headland. (2) The section of rip current which has widened out seaward of the breakers, also called head of rip. (3) Seaward end of breakwater or dam.
Industry:Engineering
Undulations produced by fluid movement over sediments. Oscillatory currents produce symmetric ripples whereas a well-defined current direction produces asymmetrical ripples. The crest line of ripples may be straight or sinuous. The characteristic features of ripples depend upon current velocity, particle size, persistence of current direction and whether the fluid is air or water. Sand dunes may be regarded as a special kind of ‘super’-ripple.
Industry:Engineering
May be either natural or artificial. Natural accretion is the buildup of land, solely by the action of the forces of nature, on a beach by deposition of water- or airborne material. Artificial accretion is a similar buildup of land by reason of an act of man, such as the accretion formed by a groin, breakwater, or beach fill deposited by mechanical means. Also aggradation.
Industry:Engineering
