Tutorial Open Channel 2
1. A 5-m wide rectangular channel is carrying a flow of 5 m3/s. If the Manning n = 0.013
and the bottom slope, So = 0.001, determine the normal depth.
2. A channel with a cross section shown in Fig. Q2 has a flow of 150 m3/s. The slope ofthe
channel bottom is two per thousand, and the Manningn for the flow surfaces is 0.03.
Compute the normal and critical depths in the channel.
Figure Q2
3. Design a trapezoidal channel to carry a discharge of 10 m3/s. The channel will be
excavated through rock by blasting. The topography in the area is such that a bottom slope
of 1 in 4000 will be suitable.
4. Design a channel to carry a flow of 6.91 m3/s. The channel will be excavated through stiff
clay at a channel bottom slope of 0.00318.
5. A rectangular channel width 4.6 m carry flow at 0.6m depth. Channel base slope = 1:400.
With Manning coefficient between 0.040 and 0.080 s/m1/3, determine (a) Minimum and
maximum flowrate in a channel (b) percentage different of the flowrate.
6. A trapezoidal channel with concrete lining designed to convey a maximum flowrate of
75m3/s with base slope 1: 2000, side slope 45o and Manning coefficient n=0.014.
Determine width and flow depth for the most efficient section channel.
7. Calculate the specific energy if Q = 6.5 m3/s flowing in a rectangular channel and 3 meter
width if flow depth are a) 2m b)1m c) 0.5m.
8. Calculate the specific energy if Q = 8.65 m3/s flowing in a trapezoidal channel with
B=2.2m and z =2 if flow depth are a) 1.5 m b)1.0m c) 0.5m.
9. The specific energy for a rectangular channel with 1.8 meter width is 1.2m. If flowrate =
0.85m3/s, determine alternate depth for the flow.
10. Flowrate in a rectangular channel 4 meter width with Manning coefficient n = 0.02 is
22.2 m3/s. Determine (a) critical depth, yc (b) critical velocity,vc and (c) critical slope, Sc.
11. Water flow in rectangular channel with q = 5.3 m3/s.m and yo=2.0m. Calculate the
minimum depth of a weir should be constructed in the channel that cause the critical depth
on it.