Using the rational method and the following rainfall IDF curves, estimate the 100-yr runoff from a 150-acre watershed covered by single-family...

Using the rational method and the following rainfall IDF curves, estimate the 100-yr runoff from a 150-acre watershed covered by single-family residential land use. The dimensions for computing time of concentration are:

Sheet flow

Length: 200 ft

Surface description: dense grass

Manning roughness coefficient: 0.24

2-yr 24-hr rainfall: 4.2 in

Slope: 0.08 ft/ft

Shallow concentrated flow

Length: 2000 ft

Surface description: unpaved

Slope: 0.2 ft/ft

Channel flow

Length: 4500 ft

Velocity: 7 ft/sec