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<br />GLOSSARY Of TERMS <br /> <br />Flood Stage. The stage or elevation at which overflow of the <br />natural banks of a stream or body of water begins in the reach or <br />area in which the elevation is measured. <br /> <br />Flood. An overflow of lands, not no~lly covered by water, that <br />are used or usable by man. Floods have two essential characteristics: <br />the inundation Of land is temporary, and, the land is adjacent to <br />and inundated by overflow from a river or stream, or an ocean, lake, <br />Or other body of standing water. <br />Normally, a "flood" is considered as any temporary <br />rise in streamflow or stage, but not the pending of surface water, <br />that results in significant adverse effects in the vicinity. Adverse <br />effects may include damages from overflow of land areas, t~porary <br />backwater effects in sewerS and local drainage channels, creation <br />of unsanitary conditions Or other unfavorable situations by deposition <br />of materials in stream channels during flood recessions, rise of <br />ground water coincident with increas<>d streamflow, and other problems. <br /> <br />Floodway. The minimum area of the flood plain that is required to <br />convey a flood peak of a selected magnitude. This Y$ually consists <br />of the most ha2ardous area of the flood plain where water velocities <br />are Significant. Areas On the landward si4e of a floodway normally <br />convey little floodflow, although they are inundated during floods. <br /> <br />Internediate Regional Flood. A flood having an average frequency <br />of occurrence in the order of Once in 100 years although the flood <br />rnayoccurinanyyear.ltisb>>.sedonstatisticalanalysisof <br />streamflow records available for the watershed and analysis of rainfall <br />and runoff characteristics in the general region of the w"tershed. <br /> <br />Flood Crest. The maxim~ stage of elevation reached by the waters of <br />a flood at a given location. <br /> <br />Low Steel Or Underclearanc... The lowest point of a bridge or other <br />structure Over or across a river. stream, Or watercourse tbat limits <br />the opening through which water flows. <br /> <br />flood Peak. Tbe maxirn~ instantaneous discharge of a flood at a <br />given location. rt u3\1ally occur~: at or near the time Of the flood <br />crest. <br /> <br />Flood Profile. A graph showing the relationShip of water surface <br />elevation to location, the latter generally ,,><pressed asdiatance <br /> <br />Standard ProiectFlood. The flood that may be expected from the most <br />SeVere combination of meteorological and hydrological conditions that <br />is considered reasonably characteristic of the geographical area in <br />which the drainage basin is located, excludin~ extremely rare com- <br />binations. Peak discharges from these floods are generally about <br />40\ to 60% of the probable "",..irnum floods for the same basins. Such <br />floods, as used by the Corps of Engin"ers, arcointendedaspracticll bl" <br />e><pressionsof thcdeqree of prt..tection that sh.ould be sought in t.he <br />design of flood control works. the failure of Which might be disastrous. <br /> <br />FloodPlain. nterelatively flat area of lowlanJs Ildjoining the <br />channel of a river, stream or watercourse, or ocean, lake, or other <br />body of standing water. which has been or may be ~~vered by floodwater. <br /> <br />abovernouth for a strearnof water flowing <br />generally dra~n to show surface elevation <br />flood, but may be prepared for conditions <br /> <br />inanopenchannel. nis <br />for the crest of a specific <br />at a given time or stage. <br /> <br />" <br /> <br />;0 <br />