Question

In a wide rectangular channel if the normal depth is increased by 20%, then what is the approximate increase in discharge?

• A. 25%
• B. 35%
• C. 40%
• D. 30%

Answer 1

The correct option is D 30%

For wide rectangular channel,
$R\simeq y$

Using Chezy's equation,

$Q=C\times By\times \sqrt{yS}$

$\frac{dQ}{Q}=\frac{3}{2}\frac{dy}{y}$

$\frac{dQ}{Q}=30\%$