The direct runoff hydrograph of a storm obtained from a

The direct runoff hydrograph of a storm obtained from a catchment is triangular in shape and has a base period of 80 hours. The peak flow rate is 30 m³/sec and catchment area is 86.4 km². The rainfall excess that has resulted the above hydrograph is

Volume of run off = Area of hydrograph

=	1	× 30 × (80 × 60 × 60)
	2

= 4320000 m³/s

Area of catchment = 86.4 km² = 86.4 × 10⁶ m²
Rainfall excess = run off

=	Volume of run off
	Area of catchment

=	4320000	= 0.05 m
	86.4 × 10⁶