Flooding

As rising global temperatures make extreme storms more common, the nation’s dams and reservoirs – crucial to keeping communities dry – are being tested. Storms in the U.S. Northeast stretched the region’s flood control systems nearly to the breaking point in July 2023. California and states along the Mississippi River faced similar flood control challenges in 2023. Managing these flood control systems is a careful balancing act. Do managers release water to make room for the storm’s runoff, increasing the risk of flooding downstream, or hold as much as possible to protect downstream farms and communities, which could increase the chance of larger floods if another storm comes through? The earlier decisions can be made, the better the chance of avoiding downstream damage. But forecasts aren’t always reliable, and waiting for the rain to fall may mean acting too late. Satellite water vapor imagery from July 9-11, 20...

When an explosion breached the Kakhovka Dam in Ukraine on June 6, 2023, much analysis focused on near-term impacts, including the flooding of the city of Kherson, threats to the Zaporizhzhia Nuclear Power Plant and consequences for Ukrainian military forces’ expected spring offensive against Russian troops. But the most severe long-term effects will fall on Southeast Ukraine’s farmers. Villages there were flooded. Roads, train tracks and irrigation canals were washed away. Crops in fields and orchards in the Kherson and Zaporizhzhia region were inundated, then left to shrivel after the water drained. The long-term ecological disaster will unfold over decades to come. Crimea, once a region known for its sunny beaches and rice fields, could dry up without irrigation. We are a U.S. political scientist with research expertise on the post-Soviet region and a Ukrainian economist who studies agriculture. While the long-term effects of the dam break are difficult to calcu...

Hundreds of industrial facilities with toxic pollutants were in Hurricane Helene’s path as the powerful storm flooded communities across the Southeast in late September 2024. Near the coast and into Georgia, Helene swept over paper mills, fertilizer factories and oil and gas storage facilities. Paper mills are among the most polluting industries on the planet – some with thousands of pounds of lead on-site from prior production practices. Florida officials reported that a retired nuclear power plant just south of Cedar Key experienced a storm surge of as much as 12 feet that inundated buildings and an industrial wastewater pond. Spent nuclear fuel stored at the site, which also flooded during Hurricane Idalia in 2023, was believed to be secure, Bloomberg reported. Further inland, the storm dumped more than a foot of rain on industrial sites in the Carolinas and Tennessee, some near waterways that quickly flooded with runoff from the mountains....

Hurricane Helene’s flooding has subsided, but health risks are growing in hard-hit regions of the North Carolina mountains, where many people lost access to power and clean water. More than 180 deaths across the Southeast had been attributed to Hurricane Helene within days of the late September 2024 storm, according to The Associated Press, and hundreds of people remained unaccounted for. In many areas hit by flooding, homes were left isolated by damaged roads and bridges. Phone service was down. And electricity was likely to be out for weeks. As a disaster epidemiologist and a native North Carolinian, I have been hearing stories from the region that are devastating. Contaminated water is one of the leading health risks, but residents also face harm to mental health, stress that exacerbates chronic diseases and several other threats. Water risks: What you can’t see can hurt you Access to clean water is one of the most urgent health concerns after a flood. People ne...

Hurricane Helene caused deadly and destructive flooding when it swept through the Southeast on Sept. 26-29, 2024. Across a broad swath of western North Carolina, where the worst flooding occurred, the amount of rainfall exceeded levels that would be expected on average only once every 1,000 years. But this wasn’t the first 1,000-year rainstorm in North Carolina this year. In mid-September, an unnamed slow-moving storm produced more than a foot of rainfall closer to the Atlantic coast. This storm inundated areas that had already been drenched by Tropical Storm Debby in August. As atmospheric scientists and state climatologists, we believe it’s important for the public to understand the risk that extreme events may occur. That’s especially true as climate change alters the conditions that create and feed storms. Here’s how scientists calculate storm probabilities, and why events like a 1,000-year storm can happen much more frequently in some places than tha...