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<br />. <br />. <br />. <br />. <br />i. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />... <br /> <br />Catchment Data <br />Location I Western Colorado (II) <br />Catchment I D = <br />Basin Area, A = <br />NRCS Soil Type = <br />Overland Flow Type I Nearly Bare Ground <br />Runoff Depths <br />Storm <br />Rainfall Frequency (years) <br />Rainfall Duration (hours) <br />Rainfall Depth, P (inches) <br /> <br />SCS TR-55 Methodoloov <br />Q = (P-0.2S)'/(P+0.8S) <br />S=(1000/CN)-10 <br />qp = Q,AQ <br /> <br />Weighted Curve Numbers, CN <br />Sub-Area <br />1 <br />2 <br />3 <br />4 <br />Sum <br /> <br />Totel Runoff <br /> <br />Hvdroloav Calculations <br />Town of Granby <br />Basin B6 <br /> <br />where: <br />Q = runoff depth (inches) <br />S = potential abstraction <br />CN = SCS Curve Number <br />A = drainage area (acres) <br />P = rainfall depth (inches) <br />Q, = Unit Peak Discharge (cfs/sm/in) <br /> <br />J~ <br />".' t:1il61 <br />;"l<:-<#:--";;;" -~$jacres <br />i').: if: 'l/-~'kiBi <br />EI <br /> <br /> <br />oeseri tion <br />Residential <br />Commercial <br />Pasture <br />Roads <br /> <br /> <br />Percent <br />25% <br />0% <br />73% <br />2% <br />100% <br /> <br />Storm 5 yr - 24 hr 10yr-24hr 50yr-24hr 100yr-24hr <br />Potential Abstration, S 2.44 2.44 2.44 2.44 <br />Runoff Depth, Q (inches) 0.25 0.35 0.84 0.98 <br /> <br />Time of Concentration <br />Overland Flow <br />From Figure 3-1, TR-55 <br /> <br />BasIn Calculation <br /> <br />Reach <br />A <br />B <br />C <br />D <br />Total <br /> <br />Peak Dlscharae <br /> <br />Channel Flow <br />T ~ = L/(1.49/n)R213 S 112 <br />where: <br />R = Hydraulic Radius n = Roughness Coeff. <br />S = Channei Slope L = Length of Flow <br />T cc = Time of Concentration, Channel Flow <br /> <br /> <br />V rcoor Tee <br />(ltIs) min <br />0,8 13.8 <br />8.4 1.4 <br />1.5 15.2 <br /> <br /> <br />8/20/02 <br />TR55-hydrology.xls <br />