Question

A 5 m wide rectangular channel carries a flow of 20 m³/s. The slope of the channel is 0.005 and the Manning’s n is 0.03. The flow encounters a 0.5 m step up that is 0.1 m long. The depths far upstream and downstream are normal.

1. Classify this channel
2. Qualitatively sketch this scenario, label gradually varied flow curves and provide appropriate depths.
3. Draw this scenario on an E-Y cycle graph, and label all depth changes.

Answer 1

Y	Specific Energy
m	m
0.4	5.497
0.5	3.762
0.6	2.865
0.7	2.364
0.8	2.074
0.9	1.907
1	1.816
1.1	1.774
1.2	1.766
1.3	1.783
1.4	1.816
1.5	1.862
1.6	1.919
1.7	1.982
1.8	2.052
1.9	2.126
2	2.204
2.1	2.285
2.2	2.368
2.3	2.454
2.4	2.542
2.5	2.630
2.6	2.721
2.7	2.812
2.8	2.904
2.9	2.997
3	3.091
3.1	3.185
3.2	3.280
3.3	3.375
3.4	3.471
3.5	3.567
3.6	3.663
3.7	3.760

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