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<br />-- <br /> <br />GLOSSARY <br /> <br />Intermediate Regional Flood. A flood having an average frequency <br />of occurrence In the order of once In 100 years although It may occ ur, <br />andhasal percent probabIlity of occurring lni'Ulyyear. <br />Sheetflcw. Broad, shllllow overland floodflows generally less than <br />2 feet deep. <br /> <br />Backwater Effect. <br />upstream from and as a <br /> <br />The rise in surface elevation of flowIng water <br />result of an obstructIon to flow. <br /> <br />Cloudburst. A sudden and extremely heavy downpour of rain that <br />is small in areal extent; of short dur<ltion; and may De (Iccompaniod by <br />lightning, thunder, and strong gusts of wi~d. <br />Flood. An overflow of water onto hmds 1"hat a~ used or usable <br />by man and not normally covered by water. Floods have two essentIal <br />CharacterIstics: The inundatIon of land Is temporary; and the land <br />is adjacent to and Inund<lted by overflow from a rIver, stream, lake, <br />or ocean. <br /> <br />Sti;mdard Project Flood. The flood that may be expected from the <br />most severe combina1"lon of meteorological and hydrological conditions <br />considered reasonably characteristic of the geographical area In whiCh <br />the drainage basin Is 10C<lted, excluding extremely rare combinations. <br />Snow Course. An established line or series of lines along which <br />snow samples are periodically 1"aken to determIne water equIvalent of <br />snowpack on a given area. <br /> <br />Normally, a "flood" is considered es any tOlTlporary rise In stream <br />flow or stage (bu1" no1"the ponding of surfacewaterl 1"hat results In <br />significant adverse effects In 1"he vIcinity. Adverse effects may include <br />damages from overflow of land areas, temporary backwater effects In <br />sewers and local draInage channels, creation of unsanitary conditions <br />or other unfavorable situations by deposition of materials in stream <br />chMnels during flood recessions, rise of groundwater coincident with <br />increased streamflow. and o1"her problems. <br /> <br />- <br /> <br />-, <br /> <br />FlocdPeak. <br />glvonlocation. <br />crest, I.e., the <br /> <br />The maximum Ins1"antaneous discharge of e flood at a <br />It usually occurs at or nOar the time cf the flood <br />maximum stage or elevatIon reaChed by the floodflow. <br /> <br />,-, <br /> <br />FloodPlain. Thorelatlvelyflatareaorlowlandsadjo\ninga <br />river, stream, watercourse, ocean, or lake, which have been or may be <br />covered by floodwater. <br />Flood Stage. The elevation of whiCh overflow of the natural bankS <br />of a stream or body of water begins In the reach or area in whiCh the <br />elevation Is measured. <br /> <br />Floodway. The channel of the stream and that portIon of the flood <br />plain that would be used to carry floodflows. <br />High Water Profile. A graph showing the realtlonshlp of water <br />surface elevation to location, the latter generally expressed as distance <br />above mouth for a stream of water fiowlng In an open channel. It Is <br />generally drawn to show surface elevation for the crest of a specIfic <br />flood, but may be prepared for conditions at a given time or stage. <br />Hydrograph. Agra.phoftiroo"sfloworsfagaatagiven locatio.'l <br />along a stream. <br /> <br />" <br /> <br />44 <br /> <br />I <br />