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First Street Outlines Flood Risk for Every U.S. Metro

The company that created realtor.com’s flood risk tab released a report by city and county. Fla. and Louisiana are top-risk states – but so are Kentucky and W. Virginia.

BROOKLYN, N.Y. – First Street Foundation – the science and technology nonprofit that developed the First Street Foundation Flood Model and Flood Factor, which realtor.com adds to listings advertised on its website – released the first nationwide community level flood resilience report. Called “The 3rd National Risk Assessment: Infrastructure on the Brink,” it highlights the 30-year flood risk for every city and county across the contiguous United States.

Florida has an extensive coastline and low-lying coastal areas, and – along with Louisiana – has some of the highest concentrations for community risk, but First Street also listed two inland states in its high-risk categories, specifically Kentucky and West Virginia. Together, those four states are home to 17 of the top 20 communities facing a higher risk from floods. Louisiana alone accounts for 6 of the top 20 most at-risk counties (30%) and is home to the No. 1 county, Cameron Parish.

The report calculates the risk of five key dimensions of community risk:

  • Residential properties
  • Roads
  • Commercial properties
  • Critical infrastructure
  • Social infrastructure

The findings are also incorporated into Flood Factor, giving Americans with an expanded scope through which to understand their personal flood risk as well as the vulnerability of their broader community.

“Our work aims to determine the amount of flooding that would render infrastructure either inoperable or inaccessible,” says Dr. Jeremy Porter of First Street Foundation. “By applying research on depth thresholds and comparing them to flood data and probability metrics, we can determine roughly the extent of flooding that would cause a road to be impassable to cars, or a hospital to be shut down.”

According to First Street’s analysis, roughly 1 in 4 (25%) of all critical infrastructure in the country are already at risk of becoming inoperable, or about 36,000 facilities. Another 1 in 4 (23%) road segments (nearly 2 million miles of road), are at risk of becoming impassable. Additionally, 1 in 5 (20%) commercial properties (919,000), 17% of social infrastructure facilities (72,000), and 14% of all residential properties (12.4 million) also face operational risk.

That number of properties will continue to grow as the climate changes, according to First Street. Over the next 30 years, it predicts an additional 1.2 million residential properties, 66,000 commercial properties, 63,000 miles of roads, 6,100 pieces of social infrastructure and 2,000 pieces of critical infrastructure will also face flood risk that could render them inoperable, inaccessible, or impassable.

“As we saw following the devastation of Hurricane Ida, our nation’s infrastructure is not built to a standard that protects against the level of flood risk we face today, let alone how those risks will grow over the next 30 years as the climate changes,” says Matthew Eby, founder and executive director of First Street Foundation. “This report highlights the cities and counties whose vital infrastructure are most at risk today, and will help inform where investment dollars should flow in order to best mitigate against that risk.”

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