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<br />GLOSSARY <br /> <br />Ba~kwater Effe~t. <br />upstraam from and asa <br /> <br />T~e rlsa In surfaca alevatlon of <br />result 01 an obstruction to flo". <br /> <br />flowing "ater <br /> <br />Standard Projec.tFlood. The flood tMtmay be expected from the <br />most savare combination of meteorological and hydrological conditions <br />that are considered reasonably characterIstic of the geographical araa <br />In which the drainage basIn is located, excluding extremely rare <br />combinations. <br /> <br />Flood. An overllow 01 water onto lands that are used or usable by <br />man and not normally covered by water. Floods have two essential <br />Characteristics: The Inundation of land Is temporary; and the lond <br />Is <ldjacent to and Inundated byoverflo" from a river. streom, loke. <br />or ocean. <br /> <br />Normally a "floo<::" is considered as any te...porary rIse In stream- <br />flow or stage (but not the pondlng of surface water) that results In <br />sIgnifIcant adverse effects In the vicinity. Adverse effects may In- <br />Clude damages from overflow of land areas, temporary backwater effects <br />In sewers and local dralnagechannels,creiltlonofunsanlt6rycondl- <br />tlons or other unfavorable situations by deposition of materials In <br />stream channels during flood recessions, rise of groundwater coincid- <br />ent with Increased streamflow. and other problems. <br /> <br />Flood Peak. The maximum Instantaneous discharge of a flood at a <br />given 10catloM. It usually occurs ator near the tlmeof the flood <br />crest, the mexl~um stage or elevation reached by the floodflow. <br /> <br />Flood Pla1n. The relatively flat /lrea or lowlands adjoining a <br />river, stream, watercourse,OCeaM, or lake, which have been or may <br />becoverod by floodwater. <br /> <br />FloodProflle. Aqraphshowlngtherolatlonshlpolwatersurfoce <br />elovatlon to location, t~e latter generally expressed as distance above <br />"",uth fora stream of water flowing In an open Channel. Itlsgener- <br /><lIly drawn to show surfacaelevatlonforthecrestola specific I 1000, <br />but ~y be prepared for conditions at a given time or stage. <br /> <br />Flood Stage. The elevation at whiCh overflow of the Odtural banks <br />of a stream or body 01 water begIns In the reach or area In which the <br />ela"ationlsmeasured. <br /> <br />Floodway. The channel of the stream and that portion of the flood <br />plain th/ltwould be used to carry floodflows. <br /> <br />Intermediate Reg10nal Flood. <br />otoccurrencelntheorderotonce <br />occur In an" yaar. <br /> <br />~ Ilood having an averoge <br />In 100 years althouqh the <br /> <br />freouency <br />tlood"",y <br /> <br />Snow Course. Anest/lblished line or series of lines along which <br />snow s<lmplas are periodically taken to determine water eq~lvalent of the <br />snowpack on a given area. <br /> <br />29 <br /> <br />30 <br />