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Aspect Backwater Effect Channel Cloudburst Correlation Confluence Conveyance Capacity DesiKnated Floodplain Detention Dike GLOSSARY DisCharge tbe quantity of water pa."ing " given stream cross sectionperunitoftillle. Rsteofflowinsstrea", is usually expressed in cubic feet per second. The general basin orientation from a higher to a lower point in relation ro eaat, west, north, and south directiona. Draina>leBaain A part of tbe aurface of the earth that is occupied by a drainage system, which conaiata of a surface stream or a body of impounded surface water together with all tributsry surface streama and bOdies of impounded sur- face water. The riae in surface elevation of flowing water upstream from and as a result of an obstruction of flow. flood An overflow on lands not notmally covered by water which are used or usable by man. Floods have two essential characteristics: (1) The inundation of land is ee..ponry. (2) The land ia adjscent to and inundated by overflow from a river or stream or an ocean, lake or other body of standing water. Normally, a flood is considered as any remporary rise in streamflow or stage. but not the ponding of surfsce water which resulta in significant adverse effects in the vicinity. Adverse effects may include damages from overflow of land areas, temporaty back- wster effects in sewers and local dlainage chsnnels, creation of unsanitary conditions ol othel unfavor- able situations by deposirion of ~aterisls in stteam channels during flood receosions, use of ground water coincident with increased 8tre~flow and other problema. A natural or artificial water course of perceptible extent with definite bed snd banks to confine and conduct continuously Or periodically flowing water. A sudden and extremely hesvy downpour of rain thst is amall in areal extent; of short duration; snd may be accompanied by lightning, thunder, and strong gusts of wind. The process of estsblishing a lelstion between a variable and One or more lelated variables. A point where two or more streams meet. a. Channel conveyance capacity is the rate of dis- charge, in cubic feer per second, which can flow in a water course with the vster Burface not greatel than the height of the channal banks. b. Ploodway conveyance capacity is the rate of dis- charge in the overflow portion of the floodway which can pass through s 9pecified ares at depths and velocities governed by the hydraulic dimensions of thefloodway. Plood, 1% Chance A type of flood, including the water surface elevation and territorial occupation thereof, whiCh can be expected to occur at any time in s given area bssed upon recorded historical precipitation and other valid data, but with an aVelage 9tatistical one percent chance of being aquslled or exceeded during anyone year. The term is used interchangeably with lOO-yesr flood or Intermediate Regional Flood, the area designated as a floodplain by official action of the board of county commissioners or the City council with the prior concurrence of the Colorado Water Con- servation Board. Hoodway The floodway is the channel of a stream, plus anyad- jacent floodplain sreas, that must be kept free of encroschment in order that the 100-year flood may be csrlied without subotantial incresses in flood heights. The slowing, dampening, or sttenuating of flows by temporarily holding the water on s sutface area, in a storage basin, or within the storm or combined sewer itself. Flood Frequency (See Probsbility) the average recurrence interval of specific discharges or water stages Which cSSe flooding. Flood Peak The msximum instantaneous discharge of a flood at a given location, It usu.111y occuts at or near the time of the flood crest. An embankment to confine or control watel, especially one built along the banks of a river to prevent OVet- flow nf lowlands. -95- - 96 -