Question

A $252{\text{km}}^2$ catchment area has a 6 hr UH which is a triangle with time base of 35 hours. What is the peak discharge of the DRH due to 5cm effective rainfall in 6hr from that catchment?

• A. 45 cumecs
• B. 115 cumecs
• C. 200 cumecs
• D. 256 cumecs

Answer 1

The correct option is C 200 cumecs



From the unit hydrograph
$\frac{Q_p{T}_B}{2}=A\times \left(\frac{1}{100}\right)$
$\frac{Q_P\times 35\times 3600}{2}=\frac{252\times {10}^6}{100}$
$\therefore Q_p=40{\text{m}}^3/\text{s}$
The peak discharge due to 5cm effective rainfall is
$5\times 40=200{\text{m}}^3/\text{s}$