ELI5- How does only 17″ of rain cause multiple feet of floodwater?

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My little girl is 7 and just isn’t wrapping her head around this and I need to find a better way to explain this.

She is so so smart because she saw the coverage of Helene, and heard 17″ and hot confused.

I told her the water runs from the high places to the low places, but then she asked why the water doesn’t leave the low places and why is it still flooded.

I’m bad at dumbing things down.

In: Planetary Science

17 Answers

Anonymous 0 Comments

Land is not flat. There are valleys that are low ground and the water that falls on higher ground rushes downhill and settles in those low spots. Think of a puddle in a parking lot x 1 million.

Another way of thinking about it… let’s say the lowest 20% of an area floods, while the 17″ from the other 80% drained down to the low point. That means they have 5x 17″ of water that settled in that low spot. That’s over 7 feet.

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