Laserfiche WebLink
<br />TABLE TWe> <br />Existing Conditions Manning "n" ,ralue,s <br /> <br />n" Value <br /> <br />Land t[~!~LpeSCr;!"ption <br /> <br />0.035 <br />0.040 <br /> <br />South Plati:e main channel <br />Old South Platte Fliver chu.tes wi1:h <br />light vegetation <br />Farm Fields <br />Farm Fields .,ith roads and fences <br />Farm Fields .,ith occasional houses, <br />trees, and roads" <br /> <br />0.050 <br />0.060 - 0.065 <br />0.070 - 0.080 <br /> <br />,~. Calibration. For tl"lis analysis, contraction and <br />expansion coefficients of 0.2 and 0..4 were used throughout the <br />study reach. The only bridge in the study :reach, Colorado <br />Highway 63, was not modeled. The rE:,;ults of th.3 HEC-2 model <br />were compared to the high water mar}; data and calculated water <br />surface elevations presented in the J'une 1'977 Special Flood <br />Hazard Information Report, South Platte River, Volume III, <br />:Gogan County - Sedgwick County, Colorado. 'I'able Three shows <br />.the results of this comparison with a May 1973 flood of 22,000 <br />'::.f.s. Table Four shows the comparison for a IOO-year flood <br />,::alculated for this study and for the 1977 F:Lood Hazard s'tudy. <br /> <br />TABLE THrom <br />COMPARISON OF COMPUTlm STAGES AND <br />MAY 1973 HISTORI<: STAGES. <br /> <br /> 1973 High 19'73 lIig'h I;EC. 22 computed <br /> Water Water ~ICI,rk lJater Surface <br />station Mark No. Elevat~&!:! EIll!!tiq.!! <br />21980 jt 29 3942., :I 3943.1 <br />26440 j/ 30 3948.,8 3948.4 <br />33540 j/ 31 3957.,4 3959.7 <br />39440 j/ 32 3969.0 3966.9 <br />51140 j/ 33 3982.7 3984.6 <br />54940 jt. 34 3990.2 3990.2 <br /> <br />6 <br />