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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 4 <br />Sheet Flow <br />Mannings n = 0.24 <br />Flow Length (ft, max 300 ft) = 300 <br />24 hr Rainfall, P2 (in) = 1.8 <br />Land Slope, s (ft/ft) = 0.583 <br />Tt (hr) = 0.198 <br />Tt (min) = 11.9 <br />Shallow Concentrated Flow <br />Flow Length, L (ft) = 1770 <br />Watercourse Slope (ft/ft) = 0.100 <br />Average Velocity, V (ft/sec, fig 3 -1) = 5 <br />Tt (hr) = 0.098 <br />Tt (min) = 5.9 <br />Channel Flow <br />Cross Sectional Flow Area, a (ft = 56 1.49 r 2/3 s 1/2 <br />Wetted Perimiter, p„, (ft) = 25.5 V = <br />Hydraulic Radius, r = a/p (ft) = 2.20 ft <br />Channel Slope, s (ft/ft) = 0.05 <br />Manning's n = 0.035 T _ L <br />V ( ft/sec) = 16.08 t <br />Flow Length, L (ft) = 190 3600 V <br />Tt (hr) = 0.003 <br />Tt (min) = 0.2 <br />Watershed or subarea Tc = <br />Lag time (hr) = <br />Lag time (min) = <br />0.300 <br />0.180 <br />10.79 <br />T = 0.007 (nl) 0.8 <br />t P 0.5 5 0.4 <br />2 <br />L <br />T t = <br />3 600 V <br />