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<br />GLOSSARY OF TERMS <br /> <br />FloOd Plain - T~e relatively flat or lowland area adjoining a river, <br />stream, watercourse, lake, or other body of standi~g water which has <br />beenorIT1<ly be covered temporarily by floodwater. For <br />administrative purposes the flood plain may be defined as the area <br />that would be inundated by t~e 100.year flood. <br />Left Stream Bank _ T~e left bank of t~e stream when loo<ing downstream. <br />Perched Channel Flow A condition where the flow elevation in the outer <br />portions of the flOOd plain is higher than the flowelevationinth e <br />ma1n channel. This condition occurs when a higher secondary Channel <br />receives inflow from some location upstream and maintains a flatter <br />slope than the main channel. <br />Reach - A hydraulic engineering term used to descrihe longitudinal <br />segrnents ofa stream or river. <br />Right Stream Bank - The right bank of the stream when looking downstream. <br />Runoff -That part of precipitHion, as well as any other flowcontribU- <br />tions, which appears in surface stredms of either perennial or <br />intermittent form. <br />Stream - Any natural Channel or depression through which water flows <br />whether continuously. interm1ttently. or periodically. includ ing <br />modification of the natural Channel or depression. <br />Structure - Anything constructed or ereCted, the use of ~ich requires a <br />more or less permanent location on or ln t~e ground. lncludes but 1s <br />not l1m1tedtobridges, buildlngs, canals, dams, ditches,diversi ons, <br />irrigat1onsystems, pumps, pipelines, railroads,roadssewage <br />disposal systems, underground conduits, water supply systems and <br />wells. <br />Typical V~lley Cross Section - An engineering drawing of J vertical <br />section of a stream channel andadjoininglandscapeasviewedina <br /> <br />Channel-Anaturalorart1ficial water course of perceptible extent witn <br />definite banks to confine and conduct continuously or periodic ally <br />flowing water. Channel flow is that water wfiich is flowing witfiin <br />the limits of tfie defined channel. <br />Flood. Water from 0 river, stream, water course, lake or other body of <br />standi ng water, that tempor~ri 1y overflows the boundari es with i n <br />which it is ordinarily confined. <br />Flood Crest - The maximum stage or elevt ion reached by the waters of ~ <br />f100data given locat1011. <br />FlOOd Frequency - A means of expressing the prob~bility of flOOd <br />occurrences as determined from statistical analysis of represent~t1ve <br />streamflow or rainfall and runoff records. Thefrequencyofa <br />p~rti cular stage or di scharge is usually expressed as occurring on~e <br />in a specified number of years. The 10., 50-. 100- Jnd 500-ye~r <br />frequency flOOdS have an average frequen~y of occurrence in the order <br />of once in the number of years as indicated. <br />lQ-Year Flood . ~. flOOd havi~~ a~ ~v..r~g~ frl'qul'ncy of occurrence of once <br />in 10 years. ItllasalOpercentchdnc,"ofbeingequ"ledor <br />e~ceeded in any given year. <br />100-Year FlOOd - A flood having ~n averag~ frequency of occurrence of once <br />in 100 years. It has a 1 per~ent chdnce of b~ing equaled or <br />exceeded in any given ye~r. <br />Flood Hazard Areas. Areas <;usceptibl.. to flood d~mdge. <br />Flood Peak _ The highest stdge or di"hdry~ dtlaln~d rluring a flood <br />eyent; also referred to as peak stage or p~dk ctis'~drge. <br /> <br />- 27 . <br /> <br />. ~l:l - <br />