When the Federal Emergency Management Agency spends millions of dollars to help rebuild schools and hospitals after a hurricane, it tries to make the community more resilient than it was before the storm. For example, if the agency pays to rebuild a school or a city hall, it can raise the building above the flood plain, reducing the chance of it being submerged again.
It sounds simple enough, but the policy hinges on a deceptively simple question: How do you define “floodplain”? FEMA and the rest of the federal government have long defined it as an area that has a 1 percent chance of flooding in any given year. That so-called 100-year floodplain standard, while more or less arbitrary, has been followed for decades – even though thousands of buildings outside the floodplain go under water every year.
Now FEMA is expanding its definition of the flood plain, following an executive order from President Joe Biden that forced government agencies to tighten rules on how they respond to the increasing risk of flooding. In a significant shift, the new standard will require the agency to consider the impact of climate change on future flood risk when deciding where and how it is safe to build.
The new rule will lead to taller and better-fortified buildings, and could help break a cycle of destruction and reconstruction that has cost the government billions of dollars over the past few decades. In a press conference announcing the rule, FEMA Administrator Deanne Criswell called it a significant change in how the government responds to disasters.
“[This rule] will allow us to improve resilience in flood-prone communities by considering future flood risk when rebuilding structures after a disaster,” she said. “This is a major win that will also allow us to end the repeated loss cycles that result from flooding and increase the safety of families and save taxpayer dollars.”
Under the new rule, the agency will “integrate current and future changes in flooding based on climate science” when estimating flood risk, taking into account sea-level rise and intensified erosion that will worsen over the course of the century. This will be easiest in coastal areas, where the science of sea level rise and flooding is well established. In riparian areas, where the science is less robust, the agency will rebuild at least as high as the 500-year flood plain, or the land that has less than a 0.2 percent chance of flooding in a given year — and sometimes even higher for essential infrastructure such as bridges and hospitals.
This is a dramatic shift from previous measurements, which relied on historical data to estimate future flooding. Because climate change has intensified since the collection of that initial data, the agency previously systematically underestimated climate-related risk. Therefore, the new system assumes that the flood risk is much higher than in the past, and that it will continue to rise as time goes on. To mitigate that risk, FEMA will build farther from the water when possible, erecting structures on stilts and poles when it can’t retreat from shore.
“The federal government really has a duty to account for a future flood risk when it provides funding to build or rebuild homes or infrastructure because it’s using taxpayer dollars,” said Joel Scata, a senior attorney at the Natural Resources Defense Council and an expert on flood policy. Under the new rule, he said, FEMA is “going to build in a way that doesn’t set people and infrastructure up for future failure.”
FEMA estimated that raising and floodproofing structures to this stricter standard could cost the agency as much as an additional $150 million over the next ten years—a proportionally small amount given the agency’s $3 billion annual disaster spending. The agency says that raising structures by 2 additional feet adds about 2 percent to the cost of the average project, but that this expense will pay for itself over the next 60 years by preventing future damage.
Local governments can still have take-down costs, often having to pay about 25 percent of the cost when FEMA repairs a damaged school or installs a flood barrier in a community. Many small towns and low-income communities have struggled to provide these matching funds, and they have been excluded from federal resilience grants as a result.
The Biden administration is not the first to view the 100-year floodplain standard as inadequate. Then-President Barack Obama tried to expand the definition after Superstorm Sandy in 2012, but the Trump administration scrapped this revised standard shortly after taking office. President Biden’s administration has now advanced further in the regulatory process than the Obama administration’s administration could, which will make it much more difficult for a potential second Trump administration to repeal it.
Local updates to floodplain standards have already shown results: Houston, Texas, saw three massive floods in consecutive years between 2015 and 2017. After Hurricane Harvey struck in 2017, the city updated its building regulations to allow construction in the 500-year floodplain. prohibited, forcing builders to raise houses much higher or build further back from rivers and streams. These standards likely prevented thousands of homes from flooding earlier this week during Hurricane Beryl, which caused several rivers and bays to flood and spill onto surrounding land.
Editor’s note: The Natural Resources Defense Council is an advertiser with Grist. Advertisers play no role in Grist’s editorial decisions.
