Water flow in a lake... 1

[Hoot60]

New engineer here. This is what happens when the fish are not bitting. If a dam gate is open and water starts flowing thru the dam, how long does it take for a boat 10 miles away to start floating towards the dam? For numbers, let's say the gate is 20ft X 20ft and is 60ft below the water level. The lake is 30ft deep and is 600 feet across. I can calculate the flow thru the gate and the volumme of water in the lake to the boat and divide, but I don't think this is how to work this problem. Any formulas and help is appreciated.

Hoot60

 

[bimr]

As stated in the 3rd post above, this is a negative surge situation. The negative surge is not stable and you will not see a wave at that distance unless you are in a dam break scenario. A negative surge wave readily flattens out.

If you evaluate it according to Chow's method, the velocity through the 30 feet deep channel will be moving at square root of g*y or 31 ft/sec. At 10 miles of distance, the velocity of flow will pass the boat in 28 minutes. You will not feel it passing.

The dam break analysis is shown in example 19-5.