In certain parts of the United States, particularly Appalachia, New England, and the Northwest, residents' ability to prepare for and respond to flooding is compromised at three different levels.

This is according to a new study from the School for Environment and Sustainability at the University of Michigan. The article will be published in the magazine Environmental Research Letters.

“It's a very concerning confluence that keeps me on edge,” said Joshua Newell, a professor at the school's Center for Sustainable Systems and lead author of the study. “The communities most at risk of catastrophic flooding are the least prepared and will be the least prepared.”

He called this triple vulnerability “triple exposure.”

The first factor in this vulnerability is that the Federal Emergency Management Agency underestimated the flood risks in many counties across the country. Second, indicators of social vulnerability, such as low income and mobility limitations, hinder individuals' ability to take preventive measures, evacuate from floods, and recover and rebuild after a flood event. Third, there is widespread skepticism in certain communities that climate change is even happening.

“It's not just the flooding, it's not just affecting socially vulnerable populations, there's also an additional layer of vulnerability because people are unprepared and unaware of the risk they face,” said Dimitrios Gounaridis, a UM research specialist and co-author of the new report.

Geographically, the team found that the triple exposure was most pronounced in the Appalachian Mountains, an area devastated by flooding after Hurricane Helene. The team's study was in the final stages of review before publication when Helene landed in the United States

“Unfortunately, this paper is timely,” Gounaridis said.

The areas most affected by Hurricane Helene's flooding, including Asheville, North Carolina, were west of the triple-exposed Appalachian hotspot, the researchers found. But the team said the disaster underscored how the dangers become greater when people do not fully assess their risks.

“Asheville should be a climate haven,” Newell said — a place that would be protected from the worst impacts of climate change.

“It is clear from our paper that this, or at least the region around it, is not the case. I think this really highlights the need for preparation in these high-risk areas and the urgency of this work.”

To identify areas exposed to triple exposure, the team combined what Gounaridis described as dozens of layers of data. They included results from a Yale University national survey of climate attitudes, data from a federal social vulnerability index and household-level flood risk estimates from the nonprofit First Street Foundation, considered more modern and robust than FEMA's.

This not only highlighted areas at tremendous risk of flooding, but also opportunities to help communities in those regions strengthen their preparedness and resilience, said Wanja Waweru, who worked on the project while pursuing her master's degree at UM made.

“These could be educational campaigns that help people better understand climate change, or policies that lift people out of poverty so that they have the additional resources to evacuate or rebuild after a disaster,” she said.

“I think authorities and organizations in these areas should continue their efforts to help people understand their risks. Hopefully this research can identify ways to meet them where they are.”