2. A trapezoidal channel has a bottom width of 4 m and side slopes of 2:1 (H:V). If the flow rate is 50 m3/s at a depth of 3.6 m, report whether the flow is subcritical or supercritical. Also determine the alternate depth (for the same specific energy). Also determine the critical depth.

Question

Gwendolyn Moran

Engineering

5 June, 13:19

2. A trapezoidal channel has a bottom width of 4 m and side slopes of 2:1 (H:V). If the flow rate is 50 m3/s at a depth of 3.6 m, report whether the flow is subcritical or supercritical. Also determine the alternate depth (for the same specific energy). Also determine the critical depth.

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Chance Mueller · Answer 1

Sum of the side slope = 2 + 1 = 3

Length of first slope = 2/3 X 3.6 = 2 X 1.2 = 2.4m

Lenght of second slope = 1/3 X 3.6 = 1.2m

Area of the trapezoidal channel = (2.4 + 1.2) / 2 X 3.6 = 1.8 X 3.6 = 6.48m²

Alternate dept = 50m³/6.48m² = 7.716m