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:

0.242-yr 24-hr rainfall:

4.2 in Slope:

0.08 ft/ft Shallow concentrated flow Length:

2000 ftSurface description:

unpavedSlope:

0.2 ft/ftChannel flowLength:

4500 ftVelocity: 7 ft/sec