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<br />BACKWATER EFFECT. <br />from ~nd as a <br /> <br />The rise in surface elevation of flowing water <br />result of an obstruction to flow. <br /> <br />up-stream <br /> <br />i <br />I <br />, <br /> <br />safety or to property. <br />FLOODPROFlLE. A graph showing the relationship Of water surface elevation <br />tolocation,thelattergenerallyexpressedasdistanceabovemouthfor <br />a stream of water flowlng in an open channel. ltisgenerallydrawnto <br />show surface elevation for the crest ofa specific flood,butmaybe <br />prepared for conditions ~t a given time or stage. <br />FLOOO STAGE. The stage or elevation ~t whiCh overflow of the natural banks <br />of a stream or body of water begins in the re~ch or area in which the <br />elevation is measured. <br /> <br />GLOSSARY <br /> <br />CHANNEL. A natural or artificial watercourse of percentible extent with <br />definite bed and banks to confine and convey continuously or periodi. <br />cally flowing water. <br />CLOUDBURST. Asuddenandextrernelyheavydownpourofrainthatis9Tlall in <br />areal extent; of short duration; and may be accompanied by lightning, <br />thunder, and strong gusts of wind. <br />OEStGNATEDFLOODPLAIN. The area designated as a floodplain by offich1 <br />actlonof the Board of COunty Commissioners or City Council with the <br />prior concurrence of the Colorado Water Conservation Board, <br />FLOOD. An overflow on landS not nonnallycovered by water and that are <br />used or usable by man. F1oodshavetwoessential characteristics; the <br />inundation of land is temporary; and the land is adjacent to and inun- <br />dated by overflow frffi1 a river or stream or an ocean,lake or other <br />body of standing water. <br />Normally a flood is considered as any temporary rise in stream flow or <br />stage, but not the pondlng of surface water, that results in signifi- <br />cant adverse effects in the vicinity. Adverse effects may inc1ude <br />damages frffi1 overflow of land areas, temporary backwater effects on <br />sewers and local drainage channels, creation of unsanitary conditions <br />or other unfavorable situations by deposition of materials in stream <br />channels during flood recessions, use of groundwater coincident with <br />increased streamflow, and other problems. <br />FLOOO,lOO-vEAR. A type of flood, including the water surface elevation <br />and territorial occupation thereof,whichcanbeexpected to occur at <br />anytime in a given area based upon recorded historical precipitation <br />and other valid data, but with an average statistical one percent <br />change of being equalled or exceeded during any one year. The term is <br />used interchangeable with a one percent f1oodor Intennediate Regional <br />Flood(seedefinitionforlntermecliateFlood). <br /> <br />INTERMEDIATE REGIONAL f"LOOO. A type of flood. including the water surface <br />el evation ~nd territorial occupation thereof, which can be expected to <br />occur at any time in a given area based upon recorded historical pre- <br />cipitation and other valid dau, but with an average statistical one <br />percentcMnge of being equalled or exceeded during anyone year. The <br />term is used interchangeably with a one percent floodorlOO-year f10 od <br />(see definition for lOa-year flood), <br /> <br />LEFTBAI<IK. The bank on the left side of a river, stream or water course as <br />the observer looks downstream. <br /> <br />PROBABILITV. The annual change of occurrence of specific hydrologic <br />l"vents, such as rainfall over a specified area orpNK discharge at a <br />specified location expressed in percent, e.g., 5\ rl"presenting one <br />change in 20 of the event occurring in any year or an average recur- <br />renceofoncein20years. <br /> <br />RECURRENCE INTERVAL. <br />flood event will <br /> <br />The average number of years <br />be equalled or exceeded. <br /> <br />within whiCh a given <br /> <br />REFERENCE POINT. A numbered point identifying a s~ecific location for <br />correlatlng the data shown in various fOmls thro~ghout t~e report. <br /> <br />RIGHT BANK. <br />lOOKlng <br /> <br />The bank on <br />downstream. <br /> <br />the right sideofa r1ver, stream or watercourse, <br /> <br />FLOOOCREST. <br />floodata <br /> <br />The maximum stage or elevation reached <br />givpolocation. <br /> <br />by the water of a <br /> <br />RUNOFF. The quantity of rainfall which flows over the surface to enter the <br />stream as discharge volume, The difference in Quantity bebeen raln- <br />fal1 and runoff represents losses to infiltration and interceptioo, <br />STREAM. Any natural channel or depression through whiCh water flows either <br />continuously, intemittently or periodically, including aoy artificial <br />modification or the natural channel or depression. <br />WATERSHED. The drainage area situated abo.ea specified point on a stream <br />including the area drained by tributary streilll1swhich enter the main <br />stream above this point. <br /> <br />FLOODFREQUENCV. (See Probabi1ity) The average recurrence interval of <br />spec1flc dlscharges or water stages which cause flooding. <br />FLOOD PEAK. The maximum instantaneous discharge of a flood at a given <br />location. It usually occurs at or near the time of the flood crest. <br />FLOODPLAIN. An area in and adjacent to 6 stream, which area Is subject to <br />floOl'llng as the result of the occurrence ofa lOO-year floodandwhic h <br />area thus is so adverse to past, current or foreseeableconstructi on or <br />land use as to constitute a significant hazard to public health and <br /> <br />26 <br /> <br />27 <br />