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<br />. <br /> <br />. <br /> <br />. <br /> <br />The 100-year flood discharge at most of the surveyed cross sections was calculated <br />using methods shown in the "Manual for Estimating Flood Characteristics of <br />Natural-Flow Streams In Colorado," by McCain and Jarrett (1976) and is shown on the <br />flood-prone-area maps. Sample discharge values were then compared with those <br />obtained by using the U.S. Soil Conservation Service (1975) method. This procedure <br />verified that the results were reasonable. Also, consulting engineering firms have <br />prepared detailed flood reports for the towns of Kiowa, Elbert, and Elizabeth; areas <br />covered by these reports are outlined on the enlarged maps. <br /> <br />Hvdraulics <br /> <br />Information from several sources was used to determine the 100-year flood limits on <br />the flood-prone-area maps. Channel cross sections were field-surveyed at points 2 to 3 <br />miles apart on the streams. This provided detailed information on the actual shape of <br />the streambed in 1979-80 and its ability to convey floodwaters. Some channels had <br />been significantly altered since the topographic maps were prepared, either by floods or <br />by man's construction activities, and occasionally by both. <br /> <br />For this study, U.S. Geological Survey computer program E431, given in "User's <br />Manual, Computer Applications for Step-Backwater and Floodway Analyses" <br />(Shearman, 1976), was used to calculate hydraulic properties of the stream at each <br />surveyed cross section. By use of the mapped stream slope and 100-year flood <br />discharge, flood height was computed and transferred to the enlarged base maps. <br />Flood width, depth, and velocity also were plotted adjacent to the numbered cross <br />sections shown on the maps. <br /> <br />6 <br />