1. The Islamic University of Gaza Faculty of Engineering Civil Engineering Department Hydraulics - ECIV 3322
Chapter 6
Open Channel

2. Example 1
Open channel of width = 3m as shown, bed slope = 1:5000, d=1.5m find the flow rate using Manning equation, n=0.025.

3. Example 2
Open channel as shown, bed slope = 69:1584, find the flow rate using Chezy equation, C=35.

5. Example 3
Circular open channel as shown d=1.68m, bed slope = 1:5000, find the Max. flow rate & the Max. velocity using Chezy equation, C=70.
Max. flow rate

6. Max. Velocity

7. Example 4
Trapezoidal open channel as shown Q=10m3/s, velocity =1.5m/s, for most economic section. find wetted parameter, and the bed slope n=0.014.

8. To calculate bed Slope
Eng. Tamer Eshtawi

9. Example 5
Determine the critical depth if the flow is 1.33m3/s. the channel width is 2.4m

10. Example 6
Rectangular channel , Q=25m3/s, bed slope =0.006, determine the channel width with critical flow using manning n=0.016

11. Eng. Tamer Eshtawi

12. Example 7
A 3-m wide rectangular channel carries 15 m3/s of water at a 0.7 m depth before entering a jump. Compute the downstrem water depth and the critical depth

13. Example 8
d1=dn d2
dn = Depth can calculated from manning equation

14. a)
d1=dn d2 b)

15. c)
d1=dn d2

16. Example 9
A trapezoidal channel with a bottom width of 5m, side slope of 1H: 1V, and a Manning n of carries a discharge of 50m3/s at a slope of Compute by the direct step method the backwater profile created by a dam that backs up the water to a depth of 6 m immediately behind the dam. The upstream end of the profile is assumed at a depth equal to 1% greater than the normal depth.

17. determine normal depth, Yn
By trial and error, Yn = 2.87 m

18. determine critical depth, Yc
By trial and error, Yc = 1.90 m
Control depth = 1.01*2.87 =2.90m

19. 12 11 10 9 8 7 6 5 4 3 2 1 L Δx So-Sfm Sfm Sf ΔE E V R P A y m *104
3.710
3.165
2.182
1.735
13.2
22.91
2.9
1250
0.455
3.545
0.057
3.380
3.222
2.080
1.779
13.49
24.0
3.0
2237
987
0.810
3.190
0.080
3.000
3.303
1.990
1.824
13.77
25.11
3.1
2937
700
1.170
2.830
0.082
2.660
3.384
1.900
1.868
14.05
26.24
3.2
4437
1500
1.732
2.268
0.260
1.875
3.644
1.680
1.997
14.90
29.75
3.5
6187
1750
2.495
1.505
1.135
4.099
1.390
2.207
16.31
36.0
4.0

20. 12 11 10 9 8 7 6 5 4 3 2 1 L Δx So-Sfm Sfm Sf ΔE E V R P A y m *104
1.135
4.099
1.390
2.207
16.31
36.0
4.0
7713
1526
3.075
0.925
0.472
0.715
4.570
1.170
2.411
17.73
42.75
4.5
9123
1410
3.408
0.592
0.481
0.469
5.051
1.000
2.612
19.14
50.0
5.0
10473
1350
3.606
0.394
0.487
0.318
5.538
0.865
2.808
20.56
57.75
5.5
11793
1320
3.729
0.271
0.491
0.223
6.029
0.758
3.005
21.97
66.0
6.0