The stormwater system of a given site includes the surfaceoverland flow which exits by a rectangular concrete channel to(Manning‘s n = 0.015) drain it. The drainage channel is 100 m long,20 cm wide, and has a longitudinal slope of 0.6%. The catchmentsurface of 1950 m2 has an average slope of 0.7%. The site surfaceis rough asphalt pavement (Manning‘s n = 0.020) and the distancefrom the upstream catchment boundary to the channel inlet is 100 m.The 25-yr design effective rainfall rate of 78.45 mm/h, which willproduce an estimated channel flow rate of 0.034 m3 /s and channelwater depth of 0.2 m.
Determine:
a) Estimate the time of concentration of the overland flow overthe site using the kinematic wave approach.
b) Estimate the time of concentration from the open channelusing the velocity approach and Manning’s equation.
c) Estimate the total time of concentration of the catchment
