$3$

Given below are the streamflows from a catchment area of $20$ km$^2$ due to a storm of $1-$hour duration. Find the surface runoff hydrograph ordinates from an effective rainfall $($net rain$)$ of $6$ cm and of duration $1$ hour. Assume a constant base flow of $15$ cumec.

Time $($hr$)$:

$0$

$1$

$2$

$3$

$4$

$5$

$6$

$7$

$8$

$9$

$10$

Stream flow $($c$)$:

$15$

$25$

$50$

$55$

$48$

$35$

$30$

$27$

$24$

$20$

$15$