What happens to flood water?

Asked by Tennis5tar (1263

) July 24th, 2007

With the flooding that's taking place in England at the moment. It leaves me wondering where the vast amounts of water go. It's not hot outside and if the water is just like a giant lake, it can't flow anywhere. Surely it can't all get absorbed through the ground after being so saturated. And if it does... where does it go after that? It can't keep going and going, can it?

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It generally flows back out through the way it came-- typically flood plains flood because their water source (river, creek, etc.) got too high.

Say you have a 10' wide creek, in a 30' wide flood plain. The normal stage of the creek is 3' below the plain. If the creek rises 3 feet, that's an additional 225 gallons per foot of creek length. If the creek rises another 3 feet, the creek will spill out onto the plain. On a 30' wide plain, you're looking at 1' of water (if my math is anywhere near correct). If the plain were 60' wide, you'd get 6" of water.

Once the flood is finished, the water will flow back into the creek, and out of the flood plain. Did that answer your question?

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