Question

For a hydraulically efficient rectangular channel of bed width 5 m, the hydraulic radius is

• A. 1.25 m
• B. 4.25 m
• C. 0.5 m
• D. 2.75 m

Answer 1

The correct option is A 1.25 m

$R=\frac{A}{P}=\frac{B.y}{B+2y}$


For hydraulic efficient rectangular channel,
$B=2y$
$\therefore R=\frac{2y^2}{2y+2y}=\frac{y}{2}=\frac{B}{4}=\frac{5}{4}=1.25$