Question

In a river carrying a discharge of $142m^3/s$ , the stage at a station A was 3.6 m and the water surface slope was 1in 6000. If during a flood, the stage at A was 3.6m and the water surface slope was 1 in 3000, what was the flood discharge (approximately)?

• A. $284m^3/s$
• B. $200m^3/s$
• C. $164m^3/s$
• D. $96m^3/s$

Answer 1

The correct option is B $200m^3/s$

Discharge is directly proportional to
$\sqrt{S}$.
$\therefore Q_2=Q_1\times \sqrt{\frac{S_2}{S_1}}$
$=142\times \sqrt{\frac{1}{3000}\times 6000}$
$=200.8m^3/s$