Question

Water table of an aquifer drops by $100\text{cm}$ over an area of $1000{\text{km}}^2$. The porosity and specific retention of the aquifer material are $25\%$and $5\%$ respectively. The amount of water drained out (expressed in $k{m}^3$) from the area is _____

• A. 0.2

Answer 1

The correct option is A 0.2
$n_r=5\%;n=25\%$
$\because n_r+n_y=n$
$\Rightarrow n_y=25-5=20\%$

Amount of water drained out
$=0.2\times 1\times 1000\times {10}^6$
$=0.2\times {10}^9{\text{m}}^3$
$=0.2{\text{km}}^3$