FEMA's flawed hazard maps are unable to predict pluvial flooding driven by climate change, Washington Post reports

Water reached the tops of cars in South Dallas,
Texas, in August. (Photo by Dkamreen Jones)

Destructive flooding ambushed sections of the U.S. throughout 2022, leaving areas waterlogged and people homeless. The Washington Post has completed an "analysis of videos taken by people who endured destruction from flooding pinpoints how federal maps are failing to reflect the growing peril that Americans face," Samuel Oakford, John Muyskens, Sarah Cahlan, and Joyce Sohyun Lee report. "Government flood-insurance maps often left residents unprepared for the threat."

In July 2022, "Brandon Jones’s St. Louis home was hit by major flooding for the second time since 2008. Cars were barely visible under several feet of turgid storm water, as record rainfall fell on the city. . . . Two days later, the area flooded all over again."

The flooding took Jones by surprise: "Jones’s Penrose neighborhood isn’t designated as a high-risk location on the Federal Emergency Management Agency’s flood maps," the Post reports. "These high-risk zones, which lie in what’s called the Special Flood Hazard Area, cover properties that the agency considers to have at least a 1 percent annual chance of flooding. This 100-year flood plain designation requires property owners with federally backed mortgages to buy flood insurance, and it influences how communities regulate development."

The Post reports that part of the reason Jones was not prepared is that FEMA's maps need an overhaul: "They capture river and coastal flooding, not inundation caused by intense bursts of rainfall, known as pluvial flooding — a particularly dangerous problem in cities, where many porous surfaces have been paved over. This makes FEMA’s designated flood hazard zones a bad match for the intense weather events that scientists say U.S. communities will face."

Daniel Swain, climate scientist at UCLA, told the Post, “It is precisely that type of flooding, urban flooding and flash flooding from shortish duration but very high-intensity downpours, that is expected to increase the most in a warming climate."