Question

Hydraulic engineers often use, as a unit of volume of water, the "acre-foot", defined as the volume of water that will cover 1 acre of land to a depth of 1 ft. A severe thunderstorm dumps 2.6 in. of rain in 30 min on a town of area 28 km2. What volume of water, in acre-feet, fell on the town?|

Answer 1

Conversion factors needed:

1 km^2 = 247.11 acres

1 ft = 12 inches.

Covert area and depth:

Area: 28 km^2 x 247.11acre/ 1km^2 = 6919.08 acres

Depth: 2.6 in x 1ft/12in. = 2.6/12 = 0.2167 ft.

Calculate volume:

Volume = area x depth

Volume = 6919.08 x 0.2167 ft = 1499.36 acre-foot