This week’s flooding in Vermont, in which heavy rainfall caused destruction even miles from any river, is evidence of an especially dangerous climate threat: Catastrophic flooding can increasingly happen anywhere, with almost no warning.
And the United States, experts warn, is nowhere close to ready for that threat.
The idea that anywhere it can rain, it can flood, is not new. But rising temperatures make the problem worse: They allow the air to hold more moisture, leading to more intense and sudden rainfall, seemingly out of nowhere. And the implications of that shift are enormous.
“It’s getting harder and harder to adapt to these changing conditions,” said Rachel Cleetus, policy director for the climate and energy program at the Union of Concerned Scientists. “It’s just everywhere, all the time.”
The federal government is already struggling to prepare American communities for severe flooding, by funding better storm drains and pumps, building levees and sea walls and elevating roads and other basic infrastructure. As seas rise and storms get worse, the most flood-prone parts of the country — places like New Orleans, Miami, Houston, Charleston or even areas of New York City — could easily consume the government’s entire budget for climate resilience, without solving the problem for any of them.
Federal flood maps, which governments use as a guide to determine where to build housing and infrastructure, are supposed to be updated regularly. But they often fail to capture the full risk — the result of a lack of resources, but also sometimes pushback from local officials who don’t want new limits on development.
And as the flooding in Vermont demonstrates, the government can’t focus its resilience efforts only on the obvious areas, near coasts or rivers.
In Vermont, the true number of homes at risk from flooding is three times as much as what federal flood maps show, according to data from the First Street Foundation, a New York-based nonprofit research group.
That so-called “hidden risk” is staggeringly high in other parts of the country as well. In Utah, the number of properties at risk when accounting for rainfall is eight times as much as what appears on federal flood maps, according to First Street. In Pennsylvania, the risk is five and a half times as much; in Montana, four times as much. Nationwide, about 16 million properties are at risk, compared with 7.5 million in federally designated flood zones.
The result is severe flooding in what might seem like unexpected places, such as Vermont. Last summer, rainstorms closed down parts of Yellowstone National Park, forcing visitors to evacuate. In March, heavy rain caused federal disaster declarations across six counties in Nevada, the driest state in the country.
The flooding in Vermont highlights the need to spend more on modeling and planning for flood events, said Mathew Sanders, who leads state resilience efforts for the Pew Charitable Trusts. “You have to look at how water is going to flow,” he said. “We sort of need to reimagine what the most strategic interventions are going to be.”
All that water often brings tragedy to places that can least handle it.
Last year, a deluge of rain touched off flash floods that surged through the hollows of eastern Kentucky. The force of the water shredded some homes, mangled trucks and clogged the remaining buildings with mud and debris. More than 35 people died.
The communities scattered through the Appalachian Mountains are familiar with flooding, with water spilling out of the creeks coursing through the area. But the ferocity of that flood left longtime families bewildered. “We went from laying in bed to homeless in less than two hours,” Gary Moore, whose home just outside Fleming-Neon, Ky., was destroyed, said in the days after the flood.
The floods aggravated by climate change were also compounded by the lingering effects of coal mining, as the industry that once powered communities receded, leaving behind stripped hillsides and mountains with their tops blown off. The loss of trees worsened the speed and volume of rain runoff.
In Houston, deadly and devastating floods have long been a familiar threat, so much so that the worst storms have become a shorthand for marking time: Tropical Storm Beta (2020), Tropical Storm Imelda (2019), Hurricane Harvey (2017) and the Tax Day flood (2016).
But as many as half of the homes breached by floodwaters in recent years were outside official flood risk zones. An analysis by the Harris County Flood Control District found that 68 percent of the homes flooded during Hurricane Harvey were outside the 100-year floodplain, because of surging water in the creeks and bayous coursing through the area.
In Summerville, Ga., a city of some 4,400 people set in the ridges in the northwest corner of the state, a flash flood swamped homes and businesses in 2021 after a deluge delivered by remnants of Tropical Storm Claudette. Much of Summerville falls outside the 100-year floodplain, and the destruction and the resulting cleanup overwhelmed the town.
Flooding has also become a source of frustration and pain in Horry County, S.C., a coastal area that includes the resort town of Myrtle Beach. April O’Leary, a resident who started a group called Horry County Rising, said in a 2021 hearing with federal emergency management officials that close to half of the homes that flood in the county were outside the designated flood zone.
“There’s really no such thing as recovery when you flood,” Ms. O’Leary told officials. “You never fully recover financially, and families constantly live in fear of flooding.”
As the threat from flooding and other climate shocks gets worse, the federal government has increased funding for climate resilience projects. The 2021 infrastructure bill provided about $50 billion for such projects, the largest infusion in American history.
But that funding still falls far below the need. This spring, the Federal Emergency Management Agency said it had received $5.6 billion in applications for two of its main disaster-preparedness programs — almost twice as much as was available.
Anna Weber, a senior policy analyst at the Natural Resources Defense Council who specializes in flood risks, said the government needs to direct more money to the most economically vulnerable communities — those places that are least able to pay for resilience projects on their own.
But the scale of intervention required is also a chance to fix old mistakes, according to Amy Chester, managing director for Rebuild by Design, a New York-based nonprofit that helps communities prepare for and recover from disasters. She said cities and towns can rethink how they build, returning to nature the land that was built on rivers, streams and wetlands, and creating new parks or other landscapes to hold rainfall.
In that sense, she said, adapting to climate change is an opportunity. “When else,” Ms. Chester asked, “are you able to rethink how you want to live?”