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<br />I; ]988 THE PUBLIC RECORD CORPORATION <br />"LL RIGHiS RESERVED <br /> <br />llCRI, ].88 <br /> <br />Page 13 <br /> <br />a. Step-Backwater Methoc. Flood ~ater surfac~ profile~ <br />may be calculated by '.:he standard step method employing <br />the Bernoulli energy equation with energy losses due to <br />friction evaluated with the Manning equation and other <br />losses evaluated by shock loss equation~, <br /> <br />b, Alternative Methods. An alternative hydraulic <br />methodology may be 2ccepted ny the Board provided it <br />has been recommended for general u~e by a governmental <br />agency or notabl e sc i ent i fi c body, is we 11 documented <br />and is available to the general ~ser. l~ the ca$e of a <br />computer program, documentation shall include a <br />published user's manual and a progra~~er's manual. <br /> <br />4. <br /> <br />Floodplain De~ineat'cn Procedures. The <br />boundaries shall be delineated by one <br />methods: <br /> <br />fl oodp 1 a in <br />of the following <br /> <br />a. Flood Contour Method. A reierencG line shall be <br />shown down the center of the low flow channel on the <br />work maps for all streams studied bv detailed methods. <br />Fl~od contours, derived from the ~ater surface profile <br />and corresponding to the map contours, shall be used to <br />define the boundaries of the 100-year floodplain on the <br />work maps. The flood contours shall have a vertical <br />interval equal to the contour interval of the work map <br />if a) the average slope of the water surface profile <br />between cross sections is flatter than one to <br />one-hundred, or b) the width of the floodplain is <br />greater than 200 feet, or c) there are, in the judgment <br />of the engineer, unusual topographic features. <br />Alternate flood contours or index flood contours may be <br />used in lieu of the above flood contour interval if the <br /> <br />.' <br /> <br />, <br />the work map contour interval and scale, <br />in an average horizontal spacing between <br />of less than I inch. A copy of the work <br />provided to the Board for review by the <br />designation and approval under this rule. <br /> <br />b. Map Contour Method. A reference line shall be shown <br />down the center of the low flow channel on the base map <br />for all streams studied by detailed methods. For the <br />selected channel and floodplain cross sections, the <br />100-year flood water surface elevations and floodplain <br /> <br />woul d resul t <br />flood contours <br />map shall be <br />staff prior to <br /> <br /> <br />THE CODE OF COLORADO REGULATIONS <br /> <br />2 CCF. 40B-1 <br />