Millions more US homes are at risk of flooding than previously known, new analysis shows
Today, around 8.7 million properties are located in Special Flood Hazard Areas as determined by FEMA’s flood maps, the legal standard used in the US to manage floodplains, determine insurance requirements and price policy premiums.
But as many as 14.6 million properties — nearly 70% more than are in FEMA’s Special Flood Hazard Areas — may actually be at significant risk of flooding, according to First Street’s modeling. The discrepancy between FEMA’s maps and this new data means that some 6 million property owners could be unaware of their current flood risk, the group says.
“If you’re a homeowner, renter or buyer in this country and you want to understand flood risk, the only data that’s available to you are the FEMA flood maps,” said Matthew Eby, First Street’s founder and executive director. “And the FEMA flood maps are made to determine flood insurance rates — not necessarily to determine what your personal flood risk is.”
However, FEMA’s flood maps do not account for the effects of climate change, a reality Grimm appeared to acknowledge in his House testimony, saying there is a “lack of consideration about future weather patterns and changing coastal conditions” in current maps.
Other shortcomings of FEMA’s flood maps have long been recognized, even by the agency itself.
In an emailed response addressing First Street’s findings, David Maurstad, FEMA’s deputy associate administrator for Insurance and Mitigation said, “FEMA is constantly working to improve the production of the Flood Insurance Rate Maps within the context of changing conditions.”
Still, this new data shines a light on a growing climate risk that millions of Americans are already facing, though many may be in the dark about their personal exposure, experts say.
“This is more evidence that shows our mapping system is not working efficiently and we need to fix it to better our understanding about flooding in the United States,” said Dr. Hamed Moftakhari, an assistant professor at The University of Alabama, who studies the threats natural hazards pose to coastal communities.
In addition to its report, First Street is also launching a new interactive modeling system called “Flood Factor,” which will allow prospective homebuyers to explore the current and future flood risk for any on or off-market property in the contiguous US.
The tool assigns a Flood Factor score between 1-10 — with one being the lowest risk and 10 being the highest — and allows users to explore how a property’s flood risk is projected to change in the coming decades.
“Sophisticated investors have privately purchased flood risk information from for-profit firms for years,” Eby said in a press release. “First Street Foundation has not only taken this kind of data to the next level, using peer-reviewed science, but is correcting an asymmetry of information by providing free access to everyday Americans.”