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GLOSSARY OF TERMS which the elevation Is measured. "004 IlsadLoss An overflow "0 lands ~, normally covered by water and thataro used or usable 'f man. Floods have two essential character- istics: T", inundation of land ;, temporary; '"' '", land Isadjacont to and inundated by overflow from a rivoror stream or an ocoan, lake, Or othor body of standing water. Normally a "flocd" is considered I>S any to/l'lpora,.y rise in stream flow 0,. stage, that results In significant adverso effects In the vicinIty. Adverse effects may InClude damages from overflow of land areas, temporary backwater effects in sewers and local drainage channels, creation of unsanitary condItions or other unfavorable situatIons by deposition of materials In stream channelS during flood recessIons, rise of ground water coincident wIth increased stream flow, and other problems. The etfect of obstructions, such as na,.row bridge openings orbulldlngsthatllmittheareatnroughwnichwate,.musttIOlO,raising the surface of the water upstroam from the obstruction. Intermediate Regional Flood A flood having an average frequency of occurrence In the order of once in 100 yegrs although the flood may occur in any year. It Is based On st~tlstical analyses of stream flow records av~ilable for thG watershed and analyses of rainfall and runoff characteristics in the "general region of the watershed." Left Bank The bank on the left side of a river, stream or water course, looking downstream. FloodPlain The relatively flat area or low landS adjoining th~ chan- nelofariver, streilmor watercourse or ocean, lake,orotherbody Of standing water, which has been or may be covered by flood water. Low Steel (orUnderclearance) See "underclearance." , loo~ Prof I Ie RIght9ank A graph showing the relationship of water surface elevation fo loclltion. the latter generally ex::>ressed as dIstance ilbovemouth fora stream of water flowing in an open channel. ItlSgen",rally drawn to show surface elevation for the crest of a specific flood, but may be prepared tor condItions at a given tlm~ or stage. The bank on the right side of a river, stream, or wate,. course, looking downstream. Flood Stage Standard Project Flood The flood that may be expected trom the most severe com- bination of meteorological and hydrological conditions that is con- sidered reasonably characteristic of the geograrhlcal area In whiCh the drainage basin Is located, excluding extremely rare combInatIons. Peak discharges for these floods are generally about 40 percent to 60 percent of the Prob~ttle MaxImum Floods for the sa~ basins. Such floods, as The stage or elevation at whiCh overflow on the natural banks 0+ " stroam or body of "ater begins In the roach or arail in 21 22