Question

Water flows down a rectangular channel that has a width of 2.2 m, a Manning's n of 0.019 and a slope of 1 in 200. Calculate the discharge in the channel when the depth of flow is 0.5 m, 1.0 m, 2.0 m, and 4.0 m. Plot a graph of depth against discharge and comment on its shape, [10 marks] A wide channel has a Manning's number = 0.021, a longitudinal bed slope of 1:250 and conveys 0.XX m3/s/m of water. Determine (a) The normal depth of flow (b) The critical depth of flow (c) Whether the channel flow is sub or super-critical (for XX, take the second and third digits of your student number So, if your student number is 987654, x = 0.87) [10 marks]

Answer 1

* ANS :- o rectangular channel, width (B) = 2.2 m no 0.019 Szabo a = A = A 23 s"? A (433 sovrum (a = sh. 10 = (0,34% 5" 200 = 13.85 y 513 Q = (8.2 xy)" 0.019x (2.2 +2y3213 (2.2+ 2y)"} **** (2.2 +243213 y (m) a ls) 0.5 2.009 11. 0A 5:32 2.0 13,028 89.68 o wide channel na oorl. Saso q=0.87 milsim Q = AR^3 st2 (a) noima derth : 43 y ' 087= y16. o 47 0.594m 0.02

® critical depth (m): PC = 0.4257 m) © Regime of flow:- [Fraseul poi 05 = gyvy V: 1.8327m) S Fr= 1.8327 19.8140.4747 FV = 0,85] <1 :. subcriticy How

Q[m3/s) 29.68 y=7.9695x -2.433 discharge(m3/s) 13 02 y(m) 5.32 2.009 0.5 1 2 4 Q(m3/s) 2.009 5.32 13.028 29.68 0 0.5 1 1.5 3 3.5 4 4.5 2 2.5 depth (m) variation between depth and discharge is like linear