Flooding

Wetlands aren’t the most eye-catching ecosystems. They include swamps, bogs, fens and other places where soil is covered by water most of the time. But they perform a huge range of valuable services, from soaking up floodwaters to filtering out pollutants and providing habitat for thousands of species of mammals, fish, reptiles, insects and birds. In a high-profile 2023 ruling, Sackett v. Environmental Protection Agency, the U.S. Supreme Court greatly limited federal power to protect wetlands. According to one estimate, this ruling stripped federal protection from up to 90 million acres of wetlands across the U.S. Today, the U.S. is losing wetlands, mainly to development and agriculture, at an accelerating rate. With Congress polarized and gridlocked, new federal wetland protection laws are unlikely to be enacted in the next several years. Some states have stepped up to fill the gap, but others have instead chosen to roll back their existing protections. This comes despit...

The French Broad River winds through the mountains of western North Carolina, fed by dozens of mountain streams, and crosses the city of Asheville. At over 2,000 feet above sea level and more than 250 miles from the coast, it is an unlikely place to prepare for a hurricane. Yet, the remnants of several hurricanes have swept through this region over the years, sending rivers in the region raging out of their banks. When these storms hit back to back, the devastation can be enormous. In September 2004, for example, remnants of Hurricanes Frances, Ivan and Jeanne all brought excessive rain to western North Carolina in the span of a few weeks, overwhelming the French Broad and other rivers in the Asheville area. Western North Carolina’s history is just one example of the inland risks from tropical cyclones. A U.S. map of hurricane storm tracks since 1851 shows that the storms and their remnants often travel far inland. Yellows to reds...

“When it rains, it pours” once was a metaphor for bad things happening in clusters. Now it’s becoming a statement of fact about rainfall in a changing climate. Across the continental U.S., intense single-day precipitation events are growing more frequent, fueled by warming air that can hold increasing levels of moisture. Most recently, areas north of Houston received 12 to 20 inches (30 to 50 centimeters) of rain in several days in early May 2024, leading to swamped roads and evacuations. Earlier in the year, San Diego received 2.72 inches (7 centimeters) of rain on Jan. 22 that damaged nearly 600 homes and displaced about 1,200 people. Two weeks later, an atmospheric river dumped 5 to 10 inches (12 to 25 centimeters) of rain on Los Angeles, causing widespread mudslides and leaving more than a million people without power. Events like these have sparked interest in so-called sponge cities – a comprehensive approach to urban flood mitigation that uses i...

Scenes from the Houston area looked like the aftermath of a hurricane in early May 2024 after a series of powerful storms flooded highways and neighborhoods and sent rivers over their banks north of the city. Hundreds of people had to be rescued from homes, rooftops and cars during storms, according to The Associated Press. Huntsville registered nearly 20 inches of rain from April 29 to May 4. More storm systems over the following weeks blew out windows in Houston high rises and caused more flash flooding on urban streets and already saturated ground in the region. Floods are complex events, and they are about more than just heavy rain. Each community has its own unique geography and climate that can exacerbate flooding. On top of those risks, extreme downpours are becoming more common as global temperatures rise. I work with a center at the University of Michigan that helps communities turn climate knowledge into projects that can reduce the harm of future climate disasters. F...

Climate change is threatening America’s water infrastructure as intensifying storms deluge communities and droughts dry up freshwater supplies in regions that aren’t prepared. Severe storms that swept through the South in April 2024 illustrated some of the risks: In New Orleans, rain fell much faster as the city’s pumps could remove it. A water line broke during the storm near Hattiesburg, Mississippi. Other communities faced power outages and advisories to boil water for safety before using it. We study infrastructure resilience and sustainability and see a crisis growing, particularly in the U.S. Southeast, where aging water supply systems and stormwater infrastructure are leaving more communities at risk as weather becomes more extreme. Neighborhoods across the New Orleans area flooded on April 10 as the region’s pumps couldn’t keep up with the rainfall. Credit: Reed Timmer. To find the best solutions and b...

In 2021, metro Detroit was hit with a rainstorm so severe that President Joe Biden issued a major disaster declaration at state officials’ request. Nearly 8 inches of rain fell within 24 hours, closing every major freeway and causing massive damage to homes and businesses. The storm was of a severity historically seen in Detroit every 500 to 1,000 years. But over the past decade, the region has experienced several other storms only slightly less destructive, one in August 2023. As the planet warms, severe rains – and the flooding that follows – may become even more intense and frequent in cities like Detroit that have aging and undersized stormwater infrastructure. These extreme events put enormous pressure on communities, but low-income urban neighborhoods tend to suffer the most I am a geomorphologist at the University of Michigan-Dearborn specializing in urban environments, water, historical mapping and flood-risk equity. My recent research, conducted...

Wild weather has been roiling North America for the past few months, thanks in part to a strong El Niño that sent temperatures surging in 2023. The climate phenomenon fed atmospheric rivers drenching the West Coast and contributed to summer’s extreme heat in the South and Midwest and fall’s wet storms across the East. That strong El Niño is now starting to weaken and will likely be gone by late spring 2024. So, what does that mean for the months ahead – and for the 2024 hurricane season? What is El Niño? Let’s start with a quick look at what an El Niño is. El Niño and its opposite, La Niña, are climate patterns that influence weather around the world. El Niño tends to raise global temperatures, as we saw in 2023, while La Niña events tend to be slightly cooler. The two result in global temperatures fluctuating above and below the warming trend set by climate change. El Niño starts as warm water builds up a...