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, . , I I GLOSSA~Y Of TER~S flood Stage. The stage or cleva~ion at which oVerflo~ of the nat~~al banks of a stream or body of water begins in the reac~ or arcJ in ~hich the elevation is m~~3urcd. Flood. A~ overflow of lands not no~mally covered hy water, that a~e used or usable by ma~. FlOOds have two essential charactc~istics: the inu~dacion of l~~d is teMporary, and the land is adjacent to and inundatcc by overflow from a river or strea~, or a~ ocean, lake, or othc~ body of standing ~ater. floodway. T~e minimum area of the flood Flain that is required to ~onvey a flood veak 0< a 5p.l~cted mag~Ltude. 7tis usu~lly conslsts of th","osthazardo\lsarea of the flood plai" wP.ere ",at.er veloci- Norrnally, a "flood" is considered a3 any tempo..ary rise in streamflow or stage, b~t not the pending of surface water, that results in significant adverse effects in the Vicinity. ~dverse effects may include damages fro~ overflow of land areas, te~porary backwater effects in sewers and local drai~age channele, creation of unsanitary conditions or other unfavorable situations by depOsi- tion of materials in stream channels during flood recessions, rise of ground water coincident with increased streaMflow, and other problems. ties ~rc signific~nt. ~reas on thc landwar~ ,~de of ~ floodw~y normally convey little floodflow, although they are inu~ated during Hoods. Ir.terJ:\ediateRegior.alFlO<ld. A flood having an a'Jerage fr"'iuency of Qccurre~ce in the order of onCe Ln lOG years although the flood may occur in a~y year. It is based on statistical analyscs of rainfall and runoff characteristics in the qenerai region of the watershed. Flood Crest. The ma~imu~ stage or elevation reached by the waters Low Steel or underclearance. The lowest poLnt of a bridge or other structure OVer or aCrOss a river, stream, or watercourse that limits the opening through which water flows. of a flood at a given location. Flood Pe"k. The ma~im~ instantaneous discharge of a flood at a giver. location. It usually occurs at or near the time of th~ Standcud Project ]<'1000. The flood that may b<; e"peeted from tht' most severe combination of meteorological and hydrological ooodi- floOdcrost. tionsthatisconsideredreasonabl,'charact"ricticofthcqcograph- t'lood pl,nn. The relatlvely flat area Or lowlands adjoining the channel of a river, str~am or watercour~c. or ocean, lake, or other body of standing water, which has b"en or ~ay be covered by floodwater. ;c~l ~Y"~ '" wj'kh tb' <1~~ln~g'" h..~in i~ 1"",,~..,-j , ~~"l'.l,l;,.,~ extremely rare c=binations. Peak discharges ,., these floocts m gsnerally about '" " '" " the probable maximum floods ,., <0, same basins. Such floods. ^' ",," " the Corps " El".gineers, .., Flood Profile. A graph showing the relationship of water surface elevation to location, the latter generally expressed as distance intended as practicable expressions of the Jegree of protection that Should be sought in th<:> de~ign of flood control works, the. failure of which might be disastrous. ~bc7C mo~th for ~ c~rca~ c~ w~tcr ~~owing in ~~ open ~l~n~cl. n .~ is generally drawn to show surface elevation for the ~re$t of a specific flood, but may be prepared for COnditions at a given time Or stage. " "