USA: Risky waters: everyone knows it's a bad idea to build new development on flood-prone land. So why do we keep doing it?
By Mike Maciag
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Nationally, much of the development that’s taken place in floodplains is a consequence of federal regulations that do little to discourage construction in flood-prone areas. Larry Larson, director emeritus of the Association of State Floodplain Managers, sees it as a system of perverse incentives. Regardless of whether states take any steps to discourage risky developments, they still receive generous disaster relief assistance when devastation occurs. The federal government typically pays for about three-quarters of disaster assistance and over 90 percent after the most destructive storms. “They need to create some incentives for states and locals to do the right thing,” Larson says. “Right now, it’s going in the other direction.”
Just 10 days before Hurricane Harvey made landfall in Texas last year, President Trump signed an executive order nullifying an Obama-era rule that required federal agencies to build public infrastructure at higher elevations and factor in climate science when constructing in floodplains. More recently, the Environmental Protection Agency finalized a proposal to replace the Waters of the United States rule, scaling back the definition of federally protected waterways and effectively weakening the mitigation banking system. The move is expected to increase development of wetland areas.
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Mounting evidence further suggests that the overall breadth and severity of flooding risks have been understated. One study published in the journal Environmental Research Letters earlier this year estimated that three times as many Americans lived in 100-year floodplains as those identified using FEMA maps, which guide local land use regulations and flood insurance premiums. The maps are widely considered to be inadequate. Most notably, they don’t account for future sea-level rise. Some communities’ maps were last updated over a decade ago. And while the standard 100-year floodplain designation is supposed to identify areas with a 1 percent chance of flooding in any given year, many regions are experiencing far more frequent flooding. A study published in Risk Analysis found that in some places, more than half of the properties sustaining flood damage were actually located outside designated FEMA flood zones.
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Local economic development and tax revenue concerns are major considerations whenever a city rebuilds following a flood, or whenever its maps are revised. Localities often resist any attempts to cede additional ground to FEMA’s flood zones, sometimes holding up the process for years. New York City challenged a FEMA proposal that dramatically increased the area of the city in flood zones following Hurricane Sandy in 2012. The two sides reached an agreement in 2016 to create two sets of maps. “Almost every place where a developing urban area intersects a floodplain, there are local pressures, typically economic and political, to find a way to add additional development to the floodplain,” says Nicholas Pinter, a professor at the University of California, Davis. “It’s a steady drumbeat.”
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