Question

. What would be the time of concentration if you used the overland flow method to calculate it? Assume the golf course acts like a shortgrass pasture.

Answer 1

The equation used for time of concentration for overland flow method , t :

t = G ( 1.1 - c ) L^0.5 / (100 S )^1/3

c = Rational method runoff coefficient. ( For Pasture Value Lies Between 0.12 - 0.62 )
G = Constant = 1.8
L = Longest watercourse length in the watershed, ft. ( Assuming Length = 4500 ft )
S = Average slope of the watercourse, ft/ft ( 900 - 650 ) ft / 4500 ft = 0.0555 ft/ft

t = 1.8 ( 1.1 - 0.50 ) x 4500^0.5 / 100 x 0.0555^1/3

t = 1.08 x 67.082 / 100 x 0.3814

t = 72.44856 / 38.14

t = 1.8995

This is time of concentration if you have used the overland flow method assuming it as shortgrass pasture .

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