GATE 2016 CE (CE1) – Question 59
A hydraulically efficient trapezoidal channel section has a uniform flow depth of 2 m. The bed width (expressed in m) of the channel is __________
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 2.29 to 2.32
Explanation
For the fully optimised trapezoid, the side slope is1/sqrt3 horizontal to1 vertical, corresponding to60° sides. Minimum wetted perimeter at fixed area gives b=2y/sqrt3. With y=2m, b=4/sqrt3=**2.309m**. If side slope were prescribed independently, the more general expression2y(sqrt(1+z²)−z) would apply.