Question

A small catchment of area 160 ha received a rainfall of 10.5 cm in 90 minutes due to a storm. At the outlet of the catchment, the stream draining the catchment was dry before the storm and experienced a runoff for 10 hours 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 the combined effect of infiltration, evaporation and transpiration is ________ $m^3$.

• A. 78000

Answer 1

The correct option is A 78000
$P-R=Q$

P = Input due to precipitation in 10 hours
$=160\times 100\times 100\times \frac{10.5}{100}{m}^3=168000m^3$

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

$Q=168000-90000=78000m^3$

Hence,the value of water not available to runoff
$=78000m^3$