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GATE 2021 ES – Question 54

Water Resources and Environmental Hydraulics · Environmental Hydraulics · 2 marks · Numerical answer

A 10 m wide rectangular channel carries20 m³/s at 1 m depth. Using g=10 m/s²,find specific energy in m, to one decimal.

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Correct answer: 1.1 to 1.3

Explanation

Flow area=10×1=10 m²,so velocity=20/10=2 m/s. Relative to the bed, specific energy is $E=y+v^2/(2g)=1+4/20=\mathbf{1.2}$ m. It excludes the channel-bed elevation because the stated datum is the bed.

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