A 10 m wide rectangular channel has a bed slope of 3.33 × 10-3an...
Width of the channel, B = 10 m
Slope of the channel, S = 3.33 × 10-3
Manning’s coefficient, n = 0.15
Normal depth, yn = 3 m
The discharge of the channel, Q
Where,
R = Hydraulic mean radius = A/P
A = Wetted area of the cross section
S = Bed slope
P = Wetted perimeter of the cross section
∴ A = B × y = 10 × 3 = 30 m2
P = B + 2y = 10 + 2 × 3 = 16 m
Q = 175.58 m3/s
Specific discharge or discharge per unit width,
∴ Critical depth,
for the rectangular channel
yc = 3.16 m
Hence, yc > yn
and yn < y < yc leads to the gradually varied profile of S2.