ENV 4561 Fall 2011 Homework # 6 Assigned: October 6, 2011 Due October 13, 2011 1) (20 points) A 4 ft rectangular channel carries a flow of 28 cfs and terminates in an overfall. The channel has a slope of 0.0018 ft/ft and n = 0.013. Determine the distance from the overfall to where the critical and the normal depths occur. End you calculations when your calculated depth is <1.5% of the normal depth. Answers will vary depending on the step size you used. Distance from free overfall to critical depth = 4.60 ft, Distance from free overfall to normal depth = 505.24 ft 2) (20 points) A concrete channel is 5 feet wide and 4 feet deep with a weir that extends across the entire width and is set to 2 ft above the channel bottom. If the water is flowing in the channel at an elevation of 145.2 ft and the channel bottom elevation is 142 ft, what is the flow over the weir? Compare the Francis, Rehbock and Basin equations . Francis (depending on eqn used) = 21.89 or 22.68 cfs, Rehbock = 23.04 cfs, Bazin = 23.47 cfs
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parshall flume, ft rectangular channel, flume crest elevation