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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 2 <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) = 0.100 <br />Tt (hr) = 0.401 <br />Tt (min) = 24.1 <br />Shallow Concentrated Flow <br />Flow Length, L (ft) = 0 <br />Watercourse Slope (ft/ft) = 0.292 <br />Average Velocity, V (ft/sec, fig 3 -1) = 1 <br />Tt (hr) _ <br />Tt (min) = <br />Channel Flow <br />Cross Sectional Flow Area, a (ft = 56 <br />Wetted Perimiter, p„, (ft) = 25.5 <br />Hydraulic Radius, r = a/p„, (ft) = 2.20 <br />Channel Slope, s (ft/ft) = 0.005 <br />Manning's n = 0.035 <br />V (ft/sec) = 5.09 <br />Flow Length, L (ft) = 1644 <br />Tt (hr) = 0.090 <br />Tt (min) = 5.4 <br />Watershed or subarea Tc = <br />Lag time (hr) - <br />Lag time (min) = <br />0.491 <br />0.295 <br />17.67 <br />0.007 <br />P 0.5 S , 0.4 <br />2 <br />L <br />T t 3600 V <br />1.49 r 2/3 s1"2 <br />V = <br />T <br />n <br />L <br />3600 V <br />