Question

A channel designed by Lacey's theory has a mean velocity of 1.1 m/s. The silt factor is 1.1. Then hydraulic mean radius will be

• A. 1.13 m
• B. 2.75m
• C. 3.13 m
• D. 4.27 m

Answer 1

The correct option is B 2.75m

$\text{Hydraulic mean radius}=R=\frac{5}{2}.\frac{v^2}{f}$

V = mean velocity = 1.1 m/s
f = silt factor = 1.1

$R=\frac{5}{2}\times \frac{{1.1}^2}{1.1}=2.75m$