Question

The area enclosed by the adjacent isohyets of a catchment basin are

Isohyets (in cm)	30-40	40-50	50-60	60-70	70-80
Area (in $k{m}^2$)	150	250	300	200	100

The average depth of annual rainfall in the basin would be________mm.

• A. 0.535
• B. 5.35
• C. 53.5
• D. 535

Answer 1

The correct option is D 535

$P_a=\frac{\left(\frac{P_1+P_2}{2}\right)A_1+\left(\frac{P_2+P_3}{2}\right)A_2+-----}{A_1+A_2+----}$

$P_a=\frac{\left(\frac{30+40}{2}\right)150+\left(\frac{40+50}{2}\right)250+----}{150+250+----}$

$P_a=53.5cm$

$P_a=535mm$