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How to Prepare for Flash Floods, According to Delaware Experts

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With climate change come unprecedented storms, flooding and even tornadoes in the First State. Here’s what to do—and what to avoid—when disaster strikes. Take note—it could save your life.

“Delaware is going to go under water.”

The words are chilling to hear. Watching it unfold through coastal inundation map through a University of Delaware digital tool is equally bleak.

“[The state] already floods at the drop of a hat, and then you throw climate change in the mix, then it’s just going to keep flooding,” says Jennifer Trivedi, an assistant professor in the Department of Anthropology and core faculty member of the Disaster Research Center at UD. “Flooding is, I think, one of the biggest problems in the United States today.”

On a national scale, Delaware charts near the bottom in terms of natural disasters. (Florida, Texas, California and Washington are among the most at-risk.) But that doesn’t mean impervious. The Delaware coastline is especially vulnerable to extreme weather events.

Sites devoted to Delaware storms of yore remember the great Ash Wednesday storm in March of 1962, and the Mother’s Day storm on May 12, 2008, which left at least one person dead and many people homeless after ocean floodwaters destroyed homes, mainly along the Delaware Bay Coast of Kent County.

Over the coming years, our state is projected to face higher temperatures, more high-heat days, increased heavy precipitation and sea level rise. The impacts from each of these threatens industries, infrastructure, natural resources and health of residents, according to Delaware Natural Resources and Environmental Control (DNREC).

That means greater risks of floods and other disasters as time progresses. Some local families are still grappling with the aftermath of Hurricane Ida, which caused massive flooding in August 2021. As Trivedi reminds, “The impacts of disasters and the recovery process are really shaped by local history and local culture.”

We rounded up four of the best-known natural disasters and filtered them through a Delaware lens. For more comprehensive disaster planning, visit PrepareDe.org, maintained by the Delaware Emergency Management Agency (DEMA).

a New Castle county road, flooded after Hurricane Ida.

In the aftermath of Hurricane Ida in August 2021, communities on Rockland Road in New Castle County were inundated by rising currents from the Brandywine River. Experts say these “one in 500-year-events” will become more common with climate change. Delaware Today photo

Flash Floods

Threat Level: 4/5

In Delaware, we often say it’s all about water,” Leathers says.

In one of the lowest-lying states in the nation surrounded on several sides by water, flooding is bound to be a challenge. Coastal flooding can be a major problem downstate. Waterways (and unique topography and population density) make New Castle County susceptible to river and stream flooding.

Some floods develop slowly during long periods of rain, or when heavy snow melts quickly. Flash floods hit quickly within a few minutes or hours of excessive rainfall. The scary news? Those events are happening more often.

“When it comes to inland flooding… we have seen an increase in the number of intense precipitation events, a lot of rain falling very quickly,” Leathers points out. “That has certainly made the flooding conditions worse.”

Infrastructure matters, too. Upstate especially, due to its impervious surfaces like blacktop and cement, dense population and unique environments, rainwater collects and runs off quickly instead of soaking into the soil.

Leathers points to the Delaware Environmental Observing System, the highest resolution statewide meteorological network in the country, which shows a higher clip of flood-producing storms in recent years that otherwise would’ve been one in 500-year events. “[This] really tells you that the climate system is changing a little bit when it comes to precipitation,” he says.

“Sometimes people over-ascribe things to the warming atmosphere, but in this case that’s almost certainly what it is related to; as the atmosphere warms, it can hold more water vapor,” Leathers says. “And we’re just seeing the fruits of that with these higher precipitation-rate storms that we’ve had.”

Rockland bridge submerged in flood water

On a national scale, Delaware charts near the bottom for natural disasters. But that could change, and the coastline is especially vulnerable.Rockland Bridge and part of Brandywine Creek State Park were submerged after Hurricane Ida. Delaware Today photo

And it will get worse. In less than 50 years, 7,000 Delawareans could lose their homes to climate-change induced flooding and sea level rise, according to a 2018 report by the Union of Concerned Scientists.

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