🧮 BASIC FLOOD MATH
Let’s use Guadalupe River near Hunt/Ingram, TX — where the river rose ~30 feet during the July 4th flood.
💧 Rainfall Reported:
10–12 inches (0.83–1 ft) of rain
Spread over an area of ~100–150 square miles in the immediate watershed
Let’s assume the higher figure:
> 1 foot of rain × 100 square miles = 2.787 trillion gallons
(Because: 1 sq. mile = 27.87 million gallons per inch of rain)
But this assumes 100% runoff — no ground absorption, no evapotranspiration, no forest buffering. That’s never the case.
Conservatively, only 30–50% of the rainfall typically becomes immediate runoff in flood events.
So even with generous estimates, we get about:
> 💧 ~1.1–1.4 trillion gallons of immediate runoff
(comparable to a large reservoir emptying in hours)
Now..
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