Question

A reservoir receives 5 ha-m water and the loss due to evaporation from the pan is 11 cm. It receives the rainfall of 5 cm over its plan area of 100 ha. The decrease in the level is observed as 3 cm. Taking the pan factor as 0.7 loss due to seepage will be

• A. 5 ha-m
• B. 6 ha-m
• C. 7.3 ha-m
• D. 5.3 ha-m

Answer 1

The correct option is D 5.3 ha-m

Evaporation loss,
$=100\times \frac{11}{100}\times 0.7=7.7ha-m$

$\text{Rainfall}=100\times \frac{5}{100}=5ha-m$

$\text{Change in storage}=100\times \frac{3}{100}=3ha-m$

Now,
$(I+p)-(E+\text{Seepage loss})=△S$
$\Rightarrow (5+5)-(7.7+X)=-3$
$\Rightarrow 10-7.7-X=-3$

X = Seepage loss = 5.3 ha-m