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Cripple Creek and Victor <br />Phase 1 VLF <br />Lag Time Calculation Using Natural Resources Conservation Service TR -55 <br />Watershed Contribution Area 5 <br />Sheet Flow <br />Mannings n = 0.24 <br />Flow Length (ft, max 300 ft) = 186 <br />24 hr Rainfall, P2 (in) = 1.8 <br />Land Slope, s ( ft/ft) = 0.250 <br />Tt (hr) = 0.190 <br />Tt (min) = 11.4 <br />Shallow Concentrated Flow <br />Flow Length, L (ft) = 1107 <br />Watercourse Slope ( ft/ft) = 0.240 <br />Average Velocity, V (ft/sec, fig 3 -1) = 7 <br />Tt (hr) = 0.044 <br />Tt (min) = 2.6 <br />Channel Flow <br />Cross Sectional Flow Area, a (ft = 3.95 1 . r 2' 3 s 1' 2 <br />Wetted Perimiter, p„, (ft) = 7.72 V = <br />Hydraulic Radius, r = a/p (ft) = 0.51 n <br />Channel Slope, s (ft/ft) = 0.211 <br />Manning's n = 0.035 �, _ L <br />V ( ft/sec) = 12.51 <br />Flow Length, L (ft) = 438 t 3600 V <br />Tt (hr) = 0.010 <br />Tt (min) = 0.6 <br />Watershed or subarea Tc = <br />Lag time (hr) = <br />Lag time (min) = <br />0.243 <br />0.146 <br />8.76 <br />T = 0.007 (nl) 0.8 <br />t P 0.5 S 0.4 <br />2 <br />L <br />T <br />3600 V <br />