Richmond now more at risk for flash flooding

Urban areas have always had a higher risk for flooding; climate change poses an even bigger threat
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Published: Mar. 9, 2023 at 1:48 PM EST
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RICHMOND, Va. (WWBT) - Flooding is the most common weather-related disaster, and flash flooding is one of the most dangerous.

You’ve heard us say it before - turn around, don’t drown! Most flash flood deaths in the United States happen when drivers try to get through flooded roadways.

To knock over an adult, it only takes 6 inches of fast-moving flood water, 12 inches to sweep away a small car, and only 18 inches to carry away large suvs, vans and trucks.

Jeremy Hoffman, chief scientist at the Science Museum of Virginia, says that compared to less populated areas, “if you live in the city, you’re going to have a higher flooding risk.”

“Many of our sewers across - not only Richmond - but across the country were designed for a climate of the past, designed for an inch over 24 hours,” said Hoffman.

Now, our storms pack a bigger punch than they used to.

“One to two inches (of rain) in a matter of hours become more frequent due to climate change,” said Hoffman, “so more rain in a shorter duration overpowers our sewer systems.”

Cities are dominated by impervious surfaces that funnel rainwater into our stormwater system, sometimes overwhelming it.

“It’s really the perfect storm of blocked sewer systems under design sewer systems, much more impervious surfaces and extreme rainfall happening all at once,” Hoffman said.

Green spaces - like parks, forests, and lawns - absorb rain and can lower flood risk.

“In the front yard of the Science Museum of Virginia, we have the green civic park project that has transformed three acres of what was an impervious parking lot into a pervious public park,” Hoffman said.

According to Hoffman, central and eastern Richmond tends to have older sewage systems and less green space.

“Planning out now how we’re going to prioritize particular neighborhoods for investments will make them more resilient to these threats in the future,” Hoffman said.

Investments like adding that greenspace and updating the stormwater system to accommodate our most intense storms.

“We can hold more water in the atmosphere than we could before,” said Hoffman. “Based on the amount of carbon emissions that we release over the next 10 to 15 years, we will see attendant increases in that intensity of our precipitation.”

Protecting the city from future floods may be costly and labor intensive, but Hoffamn said, “there’s something we can do about it and there’s hope.”