Question

A drainage system for a 40 acre field is designed to remove 3/8 inch of standing water from the entire field in 24 hours.

What flow rate (gpm) must the drainage system achieve to meet the design specification?

Answers

Steve
volume of water 40 acre * 3/8 " = 40 acre * 1/16 ft = 40*43560/16 ft^3 = 108900 ft^3

1 gal = 231 in^3 = 231/1728 = .13368 ft^3

so, our field is covered by 814632 gal of water

to drain that in 24 hours requires a rate of 814632/24 gal/hr = 33943 gal/hr = 565.72 gal/min
Steve
oops

3/8 " is not 1/16 ft.

make that fix and adjust the final figure by the right factor.

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