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<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 />. <br />. <br />. <br /> <br />Hvdroloav Calculations <br />Town 01 Granby <br />Basin B4 <br /> <br />SCS TR-55 Methodoloov <br />Q = (P-0.2S)2/(P+O,8S) <br />S=(1000/CN)-10 <br />qp = QuAQ <br /> <br />where: <br />Q = runoff depth (inches) <br />S = potential abstraction <br />CN = SCS Curve Number <br />A = drainage area (acres) <br />P = rainfali depth (inches) <br />Q u = Unit Peak Discharge (cfs/8m/in) <br /> <br />Catchment Data <br />Location Western Colorado (II) <br />Catchment ID = <br />Basin Area, A = <br />NRCS Soil Type = <br />Overland Flow Type <br />Runoff Depths <br />Storm <br />Ralnfali Frequency (years) <br />Rainfall Duration (hours) <br />Rain/ali Depth, P (Inches) <br /> <br /> <br />Weighted Curve Numbers, CN <br />Sub-Area <br />1 <br />2 <br />3 <br />4 <br />Sum <br /> <br />Percent <br />75% <br />0% <br />20% <br />5%' <br />100% <br /> <br /> <br />Description <br />Residential <br />Commercial <br />Open Space <br />Roads <br /> <br />Total Runoff <br /> <br />Storm 5yr-24hr 10yr-24hr 50yr-24hr 100 yr- 24 hr <br />Potential Abstration, S 2.35 2,35 2.35 2.35 <br />Runoff Depth, Q (inches) 0.26 0.37 0,87 1.01 <br /> <br />Time of Concentration <br />Overland Flow <br />From Figure 3-1, TR-55 <br /> <br />Channel Flow <br />T", = U(I.49/n)R213 S 112 <br />where: <br />R = Hydraulic Radius n = Roughness Coeff. <br />S = Channel Slope L = Length 01 Flow <br />T cc = Time of Concentration, Channel Flow <br /> <br />Basin Calculation <br /> <br /> <br />V Teoor Tee <br />IVs (min) <br />1.5 3.4 <br />8.1 1.4 <br />2.8 4.7 <br /> <br />F/ow <br />Reach Type <br />A ,ovat/and <br />B "Gh' [)n~J' <br />C <br />D <br />Total <br /> <br />Peak Dlscharae <br /> <br />5yr-24hr <br />1000 <br />0.01 <br /> <br />10 yr - 24 hr <br />1000 <br />0,01 <br /> <br />50yr-24hr <br />1000 <br />0.Q1 <br /> <br />100yr - 24 hr <br />1000 <br />0.01 <br /> <br /> <br />8/20/02 <br />TR55-hydrology.xls <br />