Allied & ICAR Exam Bank • ALLIED_0374 NAT • 2 Marks

Section 4: Soil and Water Conservation Engineering

Open Channel Flow

Subtopic: Open Channel Flow

Question Statement:

A most economical rectangular channel carries water at depth $y = 1.5\text{ m}$. Bed slope $S_0 = 0.001$ and Manning's $n = 0.015$. Discharge $Q = A v = (3.0 \times 1.5) \times \frac{1}{0.015} (0.75)^{2/3} (0.001)^{1/2}$ in $\text{m}^3/\text{s}$ is (rounded off to two decimal places):

Answer Key:

7.82

Step-by-Step Solution & Explanation

$A = 4.5\text{ m}^2$. $v = \frac{1}{0.015} \times (0.75)^{2/3} \times \sqrt{0.001} = 66.67 \times 0.8255 \times 0.031623 = 1.7403\text{ m/s}$. $Q = 4.5 \times 1.7403 = 7.831\text{ m}^3/\text{s} \approx 7.82-7.83\text{ m}^3/\text{s}$.
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