It just doesn't make any sense. 2-3 inches is like a drop of water compared to 10 inches!How can a couple inches of rainfall fill dry riverbeds and cause flooding?
It is not just the amount of rain that matters but the rate at which it falls. 50mm (2 inches) of rain over 24 hours will soak into the ground. 50mm in fifteen minutes cannot do that and runs off the surface down dry stream beds causing flash flooding. Enormous quantities of water are involved. If you had 50mm of rain in fifteen minutes over an area 10km X 10km (a small thunderstorm), that is 50,000cubic metres of water or 20 Olympic swimming pools dumped on the ground in 15 minutes. That water has got to go somewhere
It always happens in West Texas.How can a couple inches of rainfall fill dry riverbeds and cause flooding?
In hot climates like Arizona's, the soil becomes baked hard, and won't easily absorb much rainfall. So the water just runs over the surface and collects in the valleys, causing flooding.
you're right in that it's only 2-3 inches. but all that water has to go somewhere. if the water is not absorbed by the ground, it flows down and quickly builds up.
take a bathtub with 2-3 inches of water. and then tip it over. that's what happens.How can a couple inches of rainfall fill dry riverbeds and cause flooding?
that 2-3inches of water is not the totality of the height of the rainwater. it is just the measurement collected from the rain gauge, and a "real-life" scale is used to measure the height of the rainwater, and what are its effects to a city or a place.
Dry riverbeds usually have a large basin above them from where the water will come from when it does rain and by the time all of the water (from a large area) reaches the dry riverbed where you are it will likely result in quickly rising water at great speed.
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