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<br /> <br />FI GURE 11 <br /> <br />Highway 78 were used to estimate the stages in Table 5. If greater accu- <br /> <br />racy is desired, backwater profiles should be computed for the estimated <br /> <br />discharges through the reach. The indicated 100-year flood plain is <br /> <br />plotted on Fig. 11. <br /> <br />TABLE 5 ~ Estimated Discharges and Elevations <br /> <br />Location <br /> <br /> Estimated <br />Flood Return Period Elevation Discharge <br /> (Years) (Ft. MSL) (C,F,5, ) <br /> 10 882.0 9400 <br /> 25 883,3 12000 <br /> 50 884.3 14100 <br /> 100 885.2 16200 <br /> 500 887.3 21700 <br /> 10 886.4 9400 <br /> 25 888.6 12000 <br /> 50 889,1 14100 <br /> 100 891.4 16200 <br /> 500 894.8 21700 <br /> <br />State Highway 6 <br /> <br />U. S. Highway 78 <br /> <br />Sta2e Method: <br /> <br />Use of the "stage index slope" method requires stage approximations <br /> <br />for the 10 and 25-year flood~. From the estimated values in Table 5, <br /> <br />the SIS at State Highway 6 is 1.3 ft. and that at U. S. Highway 78 is <br /> <br />2.2 ft. By using the regionalized skew coefficient of +0.05, the nor- <br /> <br />malized stages are determined from Fig. S as NSSO = 1. 71. NS 100 = 2.40, <br /> <br />and NS500 = 3.9S. Stages estimated from Eq. 7 for the State Highway 6 <br /> <br />SCALE: 1" = 2000' <br />BASE MAP: U.S.G.S. QUADRANGLE SHEET <br /> <br />location are S50 = 884.2 ft. msl, SlOO = 88S.1 ft. msl, and 5500 = <br />887.1 ft. mal. Elevations at the U. S. Highway 78 location are 550 <br /> <br />FLOOD PLAIN MAPPING - SWEETWATER CREEK - STATE <br />HIGHWAY NO. 6 TO U. S. HIGHWAY 78 <br /> <br />890.1 ft. msl, 5100 = 891.7 ft. msl, and SSOO = 89S.1 ft. msl. <br /> <br />26 <br /> <br />27 <br />