Drainage Design Manual - the City of San Luis Obispo

Table 4-8Example Time of Concentration ComputationSegment 1 2 3 4 5Type of Flow Overland Shallow Conc. Shallow Conc. Channel ChannelLength L(m) 50 130 170 540 300Upper Elevation (m) 181 164 106 89 67Lower Elevation (m) 164 106 89 67 61Watercourse Slope S 0.34 0.45 0.10 0.04 0.02Watercourse Slope in % S p 34 45 10 4 2Watercourse n n/a n/a n/a 0.03 0.045Approx Channel top width (m) n/a n/a n/a 1.5 3Approx Channel Depth (m) n/a n/a n/a 0.5 1Hydraulic Radius R (m) n/a n/a n/a 0.30 0.60Interception Coefficient k n/a 0.619 0.491 n/a n/aEquation to Compute Velocity n/a Equation 3 Equation 3 Equation 5 Equation 5Velocity (m/s) n/a 4.1 1.6 3.0 2.2Method to Compute Time Figure 4-1 Equation 4 Equation 4 Equation 4 Equation 4Time (minutes) 9 0.5 1.8 3.0 2.2Total T c = 16.6 minSLO Creek Drainage Design Manual 33 February 2003