Question

The excess runoff hydrograph from a catchment area $10k{m}^2$ due to a storm of 6 hrs duration has been observed to be triangular in shape. The peak flow is observed to be $10m^3/s$ and the base length is 20 hrs. The rainfall excess in the catchment is

• A. 5.1 cm
• B. 3.6 cm
• C. 4.5 cm
• D. 2.5 cm

Answer 1

The correct option is B 3.6 cm

$\text{Total runoff in}{m}^3=(\frac{1}{2}\times 20\times 60\times 60\times 10)$
$=360,000m^3$
$\therefore \text{Rainfall excess}=\left(\frac{360,000}{10\times {10}^6}\right)m$
= 0.036 m
= 3.6 cm