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I:;LOSSARY OF TERrlS Th'e hor I zonta I angu I ar measurement of east. or west of a north-south reference line. a line, i"n-"deqrees, Flood Profi Ie A graph showinq the relationship of water surface elevation to location, the latter generally expressed as distance above mouth for a stream of water f I owi ng in an open channe I. It. is nenera II y .drawn to show surface elevation for the crest of a specific flood, but may be prepared for conditions at a given time or sta~e. Bear I n'l , Flood An overflow on lands not normally covered by water and that ~re used or usable by man. Floods have two essential characteristics: The inundation of land Is temporary; and the land is adjacent to and inundated by overflow frOM a river or stream or ~n ocean, lake or other body of standino water. Flood Sta(je The stage or elevation at which overflow of the natural hanks of a streaM or body of water beqlns in the reach or area in which the elevation .Is measured; I.forma II y a flood is cons i dered as any temporary rise in stream- flow or stage, but not the pondino of surface water, that results in significant adverse effects in the vicinity. Adverse effects may include damages from overflow of land areas, temporary backwater effects in sewers and local drain~ge channels, creation of unsanitary conditions or other unfavorable situations by deposition of Materials in streaM channels durinn flood recessions, use of 'lround water coincident with increased streamflow, and other prohlems. Head Loss The effect of obstructions, such as narrow bridge openings or huildings that I iMit the area through which water must flow, raising the surface of the water upstream from the obstruction. Flood r.rest The Maximum stane or elevation reached hy the waters of a flood at a niven location. Intermediate Renional Flood A flood havinq a one percent orobability of occurrence in any year or an averaqe frequency of occurrence in the order of once in 100 years. The flood may occur in any year. It is based on statistical analysis of streaMflow records and analyses of ralnfal I and runoff characteristics in the general region of the watershed. Left Rank Flood Plain The relatively flat area or lowlands adjoininn the channel of a river, stream or water course or ocean, la~e or other body of standing water, which has been or may be covered by floodwater. The bank on the left side of a river, stream or water course, looklnn downstream. Reference Point A numbered point identifying a specific location for correlating the data shown in various forms throughout the report. 33 34