A dam has been constructed across a river at a location where the river bed is...

 

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A dam has been constructed across a river at a location where the river bed is at RL 154.0 m. The Full Supply Level is at RL 184.0 m and the freeboard is 3.50 m. The spillway is 45.0 m long and the flow rate over the spillway (Q, in m³/s) is given by Q = 2.2LH1.5 in which L is the spillway length (in m) and H is the height of the water level above the crest (in m). From survey information the following relationship has been derived between the volume of the reservoir basin (V, in m³) and the elevation (h, in m) above the base of the dam (the river bed level): V = 665h2.9 a. Determine the maximum flow rate over the spillway and the maximum encroachment on the freeboard caused by the following flood hydrograph entering the reservoir. Assume that the reservoir is 100% full before the arrival of the flood Time (hrs) 0 0.5 1 1.5 2 2.5 3 3.5 4 Flow rate (m³/s) 0 21 49 275 570 840 985 878 677 Time (hrs) 4.5 5 5.5 6 6.5 7 7.5 00 8 Flow rate (m³/s) 494 346 250 180 102 50 20 0 How much advance warning of the flood would be necessary to enable the necessary drawing down if the outlet works have a capacity of 20 m³/s? How would you determine if this is feasible, and how could this warning be obtained in real time? A dam has been constructed across a river at a location where the river bed is at RL 154.0 m. The Full Supply Level is at RL 184.0 m and the freeboard is 3.50 m. The spillway is 45.0 m long and the flow rate over the spillway (Q, in m³/s) is given by Q = 2.2LH1.5 in which L is the spillway length (in m) and H is the height of the water level above the crest (in m). From survey information the following relationship has been derived between the volume of the reservoir basin (V, in m³) and the elevation (h, in m) above the base of the dam (the river bed level): V = 665h2.9 a. Determine the maximum flow rate over the spillway and the maximum encroachment on the freeboard caused by the following flood hydrograph entering the reservoir. Assume that the reservoir is 100% full before the arrival of the flood Time (hrs) 0 0.5 1 1.5 2 2.5 3 3.5 4 Flow rate (m³/s) 0 21 49 275 570 840 985 878 677 Time (hrs) 4.5 5 5.5 6 6.5 7 7.5 00 8 Flow rate (m³/s) 494 346 250 180 102 50 20 0 How much advance warning of the flood would be necessary to enable the necessary drawing down if the outlet works have a capacity of 20 m³/s? How would you determine if this is feasible, and how could this warning be obtained in real time?

Answer rating: 100% (QA)

To solve this problem we need to follow these steps a Determine the maximum flow rate over the spillway and the maximum encroachment on the freeboard ... View the full answer