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I" '~h;': '1 ~', "', :.,",1 "":" .. , ".", " ;, "'," .. ., " f it ,fi' 'It . .. ~ 'I If;' ". . . ! ~ . ~ ~ GLOSSARY OF TERMS O~, Surface of road~ay or base of rail at center of bridge. "0<>> 110 o\l9rflolo' on lands not normally covered by "ater lInd that are used or usable by man. Floods have two essent!al cPlaracter- Istlcs:TheinundaTlonof land Is temporary; andTne land Is adJacent to /Ind Inundated by overflow from 11 river or stre.llm or an ocean, lake or other body of standing "ater. Normally a flood is considered as any temporary rise in strellm flow or stage, but not the pandlng at surt"ce ...ater, that results In significant adverse effects in the vicInity. Adverse etfectsmaylncludedllmag9sfromovertlowof landiilr","s,tempo....II,...Y backwateretfecTsiosewersand local drainage channels. creatIon of ~nsanltary conditions or other ~nfavorable slt~atlons by deposi- tion of materials In stream channels d~rlng flood recessions, use of groond water coincident with incre"sed streamflow, and other problems. I Flood Crest The maximum stage or elevation roached Ly the waters 01 a flood at a given location. FloodPlain Tho relatively flat aroa or low lands adjoinlr~ the channel of a river, stream or water cOlJrse or ocean, lake or other body of standing water, which has been or may be covered by flood water. FloodProtile A graph showing the relationship of water surtace 28 . elevation to location, the latter generally expressed as distance abovemauthfora stream at waterflowlnq In an open channel, It Is generally drawn to show surface elevation for the crest of a specific flood, but may be prepared for conditions at a given time or stage. Flood Stage The stage or elevation at which overflow of the nat~ral bankS of a stream or body of water begins In the reach or area In whIch the elevatIon is measured. Head Loss The effect of obstructions, such as narnew bridge open- ings or buildings that limit the area through which water must flow, raising the surface of the water upstream from tho obstruction. Intermediate Regional flood A flo:>d having a one percont probabIlity of occurrence In any year of an average frequency of occurrence In the order of once in 100 years. The f load may occur In any ye~r. It is based on statistical analysis of stream flow records and ~naIYS9S of rainf~11 and runeff c~aracter!stlcs In the ~eneral region 01 t~e watershed. Left Bank The bank on the left side of a river, stream or water coorse, looking downstream, Rlq~t Bank The bank on the right side of a river, stream or water course, looking downstream. 29