Water experiment shows risks of flash flooding after periods of drought

‘It demonstrates the problem that parched soil struggles to soak in water,’ scientist said

An experiment by a scientist at England’s University of Reading seeks to show how the risk of flash floods increases from heavy rain after a period of drought. Credit: Dr Rob Thompson/University of Reading via Storyful

A scientist at England’s University of Reading shared a video of a unique water experiment he conducted that shows how water is absorbed into different soils.

Rob Thompson, who conducted the experiment, said “it demonstrates the problem that parched soil struggles to soak-in water.”

The experiment, which can be seen in the video player at the top of this article, shows water soaking into wet grass, grass that’s been exposed to normal summer conditions and grass that’s been exposed to extreme hot temperatures.

Water soaks into the wet grass almost immediately but the parched soil hardly soaks up any water at all.

“Damp grass takes 9 seconds, moist grass (more like normal in summer) takes 52 seconds and parched grass (most this year) looked likely to take at least 15 minutes... but I got bored,” Thompson said on YouTube.

A tweet from the university states that the experiment helps show why heavy rainfall could potentially be dangerous and lead to flash flooding after a period of severe drought.

“While widespread flooding is not in the forecast anytime soon, this experiment does a great job showcasing that localized heavy rains can quickly create runoff and cause ponding on roads — especially when we’re in a drought,” said KSAT Meteorologist Sarah Spivey.

“This summer, San Antonio is experiencing the worst drought since 2011. It’s possible that our next big rain event, whenever that may be, will bring the risk for flash flooding. In fact, it’s very common to experience flash flooding in San Antonio, even when we’re not in a drought,” Spivey said.

View the current forecast here.

About the Author:

Mary Claire Patton has been a journalist with KSAT 12 since 2015. She has reported on several high-profile stories during her career at KSAT and specializes in trending news and things to do around Texas and San Antonio.