Question

A field of 3 acres with a runoff coefficient of 0.55 and a field of 5 acres with a runoff coefficient of 0.75 experience a rainfall intensity of 5.5 in/hr. If the runoff drains to a common collector, the peak flow in the collector is most nearly;

Answer 1

Answer:

107,768 ft³/hr

Explanation:

Given that :

FIELD A:

Runoff Coefficient (C1) = 0.55

Field size (s1) = 3 acre

FIELD B:

Runoff Coefficient (C2) = 0.75

Field size (s2) = 5 acre

Rainfall intensity (I) = 5.5 in/hr

We need to convert ;

Field size to ft²

1 acre = 43560 ft²

s1 = 3 acre = 43560 * 3 = 130,680 ft²

s2 = 5 acre = 43560 * 5 = 217,800 ft²

Rainfall intensity to ft/hr

1 inch = 0.0833 ft

5.5 in/ hr = (0.0833 * 5.5) ft/hr = 0.45815 ft/hr

Peak flow :

(C1 * s1 * I) + (C2 * s2 * I)

(0.55 * 130680 * 0.45815) + (0.75 * 217800 * 0.45815)

32929.0731 + 74838.8025

= 107767.8756 ft³/hr