Allied & ICAR Exam Bank • ALLIED_0390 NAT • 2 Marks

Section 4: Soil and Water Conservation Engineering

Open Channel Flow

Subtopic: Open Channel Flow

Question Statement:

In a rectangular channel of width $b = 3.0\text{ m}$, total discharge is $Q = 9.0\text{ m}^3/\text{s}$. Discharge per unit width is $q = Q/b = 3.0\text{ m}^2/\text{s}$. Taking $g = 9.81\text{ m/s}^2$, critical velocity $v_c = \sqrt{g y_c}$ where $y_c = (q^2/g)^{1/3}$. The value of $v_c$ in m/s is (rounded off to two decimal places):

Answer Key:

3.10

Step-by-Step Solution & Explanation

$y_c = (9.0 / 9.81)^{1/3} = (0.91743)^{1/3} = 0.9717\text{ m}$. $v_c = \sqrt{9.81 \times 0.9717} = \sqrt{9.532} = 3.087\text{ m/s} \approx 3.09-3.10\text{ m/s}$. Alternatively, $v_c = q / y_c = 3.0 / 0.9717 = 3.087\text{ m/s}$.
← Previous (ALLIED_0389) Next (ALLIED_0391) →

Practice In Authentic CBT Exam Interface

Test your skills under authentic timed conditions with live scoring and AIR percentile ranking.

Launch CBT Mock Test