Question

A small catchment of area $150ha$ received a rainfall of $10.5cm$ in $90minutes$,due to a storm. At the outlet of the catchment, the stream draining the catchment was dry before the storm and experiences a runoff for $10hours$ with an average discharge value of $2.5m^3/sec$.The stream was again dry after the runoff event. The amount of water which was not available to runoff due to combined effect of infiltration, evaporation and transpiration is ____ $m^3$

• A. $96\times {10}^4$
• B. $67500$
• C. $247500$
• D. $114\times {10}^4$

Answer 1

The correct option is B $67500$

$P-R=Q$

$P=\text{Input due to precipitation in 10 hours}$
$=150\times 100\times 100\times \frac{10.5}{100}{m}^3=157500m^3$

$R=\text{Runoff}=2.5\times 10\times 60\times 60=90000m^3$

$Q=157500-90000=67500m^3$

Hence, the volume of water not available to runoff
$=67500m^3$