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<br />I <br /> <br />I <br /> <br />I <br /> <br />Flood <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />Flood, 1% Chance <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />Flood Frequency <br /> <br />I <br /> <br />Flood Peak <br /> <br />I <br /> <br />Floodplain <br /> <br />I <br /> <br />I <br /> <br />Flood Profile <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />- <br /> <br />An overflow on lands not normally covered by water <br />which are used or usable by man. Floods.have two <br />essential characteristics: (1) The inundation of <br />land is temporary. (2) the land is adjacent to <br />and inundated by overflow from a river or stream <br />or an ocean, lake or other body of standing water. <br /> <br />Normally, a flood is considered as any temporary <br />rise in streamflow or stage, but not the ponding of <br />surface water which results in significant adverse <br />effects in the vicinity. Adverse effects may include <br />damages from overflow of land areas, temporary back- <br />water effects in sewers and local drainage channels, <br />creation of unsanitary conditions or other unfavor- <br />able situations by deposition of materials in stream <br />channels during flood recessions, use of ground <br />water coincident with increased streamflow and other <br />problems. <br /> <br />A type of flood, including the water surface elevation <br />and territorial occupation thereof, which c~n be <br />expected to occur at any time in a given area based <br />upon recorded historical precipitation and other valid <br />data, but with an average statistical one percent <br />chance of being equalled or exceeded during anyone <br />year. The term is used interchangeably with 100-year <br />flood or Intermediate Regional Flood. <br /> <br />(See Probability) The average recurrence interval of <br />specific discharges or water stages which cause flooding. <br /> <br />The maximum instantaneous discharge of a flood at a <br />given location. It usually occurs at or near the time <br />of the flood crest. <br /> <br />An area in and adjacent to a stream which is subject <br />to flooding as a result of the occurrence of a 1% Chance <br />Flood. Thus it is so adverse to past, current, or fore- <br />seeable construction or land use as to constitute a <br />significant hazard to public health and safety or to <br />property. <br /> <br />A graph showing the relationship of water surface <br />elevation to location, the latter generally expressed <br />as a distance above the mouth for a stream of water <br />flowing in an open channel. It is generally drawn to <br />show the surface elevation for the crest of a specific <br />flood, but may be prepared for the conditions at a <br />given time or stage. <br /> <br />-33- <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />Flood Stage <br /> <br />I <br /> <br />Left Bank <br /> <br />I <br /> <br />Log-Pearson Type III <br />Distribution <br /> <br />I <br /> <br /> <br />Low Hazard Zones <br /> <br />Meander <br /> <br />Obstruction <br /> <br />Peak Discharge <br /> <br />Precipitation <br /> <br />Probability <br /> <br />Reach <br /> <br />Recurrence Interval <br /> <br />- <br /> <br />The stage or elevation at which overflow of the <br />natural banks of a stream or body of water begins <br />in the reach or area in which the elevation is <br />measured. <br /> <br />The bank on the left side of a river, stream, or <br />water course as the observer looks downstream. <br /> <br />A statistical distribution used in flood frequency <br />analysis, which is described by three parameters: <br />(1) the mean; (2) the standard deviation; (3) the <br />coefficient of skewness of the logarithms; of the <br />sample observations. <br /> <br />That area of the floodplain in which the waters of <br />a 1% chance flood will not attain a maximum depth <br />greater than one and one-half feet. <br /> <br />The winding of a stream channel. <br /> <br />Any ,natural or manmade object existing in,along, <br />across, or projecting i.nto any channel, water course, <br />or regulatory flood hazard area which may impede, <br />retard, or change the depth or the direction of flow <br />of water either by itself or by catching or collecting <br />debris carried by such water, or that is placed where <br />the flow of the water might carry the same downstream <br />to the damage of life or property. <br /> <br />The largest value of streamflow attained by a flood, <br />usually reported in units of cubic feet per second (cfs). <br /> <br />Is the <br />of the <br />face. <br />sleet, <br /> <br />discharge of water, in liquid or solid state, out <br />atmosphere, generally upon a land or water sur- <br />Precipitation includes rainfall, snow, hail, and <br />and is therefore a more general term than rainfall. <br /> <br />The annual chance of occurrence of specific hydrologic <br />events, such as rainfall over a specified area or peak <br />discharge at a specified location. it is expressed in <br />percent, e.g., 5% representing one chance in 20 of the <br />event occurring in any yea~ or an average recurrence <br />of once in twenty years. <br /> <br />A segment of the river defined between two specified <br />points. <br /> <br />The average interval of time, in years, within which a <br />given flood will be exceeded once. <br /> <br />-34- <br />