Question

A rectangular open channel of width 4.5 m is carrying a discharge of $100m^3/sec$. The critical depth of the channel is

• A. 1.31 m
• B. 3.69 m
• C. 2.16 m
• D. 7.09 m

Answer 1

The correct option is B 3.69 m

The critical depth for a rectangular channel is given by
$y_c^3=\frac{q^2}{g}$

But $q=\frac{Q}{B}=\frac{100}{4.5}=22.22m^2/sec$

$\therefore y_c^3=\frac{(22.22{)}^2}{9.81}$

$\Rightarrow y_c=3.69m$