University of Minnesota researchers: More nature, less concrete to control Mississippi River flooding

The concrete walls and barriers that line much of the Mississippi River along cities in the Upper Midwest aren’t suited for managing floods.

Certain hot spots, including portions in St. Paul, brace for flooding each spring when the river frequently rises and enters city streets.

Annual flood damage in the Upper Mississippi River Basin, from Minnesota south through Missouri, is extensive. Each year, flooding from the river and its tributaries is expected to cause $340 million in damage, according to a new academic project led by University of Minnesota researchers.

That damage is only expected to rise with climate change driven by the burning of fossil fuels, said Philip Adalikwu and Nfamara Dampha, two U scientists working on the project. They are part of an effort to evaluate the value of nature-based solutions that can help mitigate flood risk and provide more environmental and societal benefits for communities along the river.

“Much of the infrastructure along the Upper Mississippi was built for a different climate, and it’s struggling to keep up with today’s extremes,” Adalikwu said.

The project, “Nature’s Value in Reducing Flood Risk Impacts in the Upper Mississippi River Basin,” is in its second and last year, and is analyzing which communities are most vulnerable. The effort is funded by the Midwest Climate Adaptation Science Center, a collaboration between the U.S. Geological Survey and the U.

Researchers want to equip those areas with the data to decide whether it’s worth restoring natural features, such as lowland forests and wetland grasses, along the water to help mitigate flooding.

Each community must decide for itself what solutions to explore, Dampha said. The study is working to provide metrics on the cost of flooding, the price of naturalization and the potential for those changes to help people living near the river in ways that go beyond flood mitigation.

“What nature offers is several other co-benefits,” Dampha said.

Federal, state and local governments spend millions of dollars each year responding to flooding and natural disasters. Last summer, southern Minnesota counties were rocked by flooding from the Mississippi and tributary rivers.

The most notable incident was the failure of the Riparian Dam along the Blue Earth River in June 2024. Gov. Tim Walz requested a major disaster designation from the Federal Emergency Management Association (FEMA), which was approved by the Biden administration. A FEMA report estimated the total damage at $48 million.

Minnesota and much of the Midwest is getting warmer and wetter due to climate change, which makes major flood years like 2024 more likely. Increased temperatures bring more moisture, which increasingly comes in larger storms that deposit a large amount of rain at once, according to data from the Minnesota Department of Natural Resources. Cities experience flash flooding that can temporarily overrun drainage systems. Agricultural areas see large swathes of farmland covered with water for weeks after a flood.

“These conditions are going to get worse with climate change,” Adalikwu said.

The project is examining the past to predict how climate change could alter vulnerable points across the Mississippi River basin in the future. The key is figuring out how vulnerable communities near the river cope with those changes, said Adalikwu, who has spent the past year mapping the Upper Mississippi River Basin and identifying areas most vulnerable to flooding.

Natural flood plain features like wetlands and forests are better equipped to absorb and process large amounts of water. Before people harnessed waterways for industrial power and agriculture, those systems were everywhere.

“The benefit of these is they soak up water like a sponge,” Adalikwu said.

Those buffer zones protected the ecosystem and the people who depended on it.

Restoring those natural landscapes would bring other benefits, too, Dampha said. More trees and plant life sequesters carbon from the atmosphere, prevents erosion and increases pollination. That creates cleaner air and better habitat for birds and animals. Water has time to soak into the land and descend to fill aquifers, which can improve the quality and quantity of drinking water.

A key goal for the project this year is getting buy-in and feedback from communities. The group is holding monthly meetings with local governments, tribal nations, community-based nonprofits and farming organizations to discuss their needs.

For most state and local governments, decisions about how to deal with flooding come down to cost, said Dampha, the lead scientist at the U’s Natural Capital Project, which focuses on developing a more sustainable environmental future.

The project is working to provide data to justify using elements from nature to replace man-made tools like concrete barriers, which are also known as “gray infrastructure.” That data could include potential savings on flood emergencies, the social cost of carbon that could be sequestered from the atmosphere, and the potential for increased productivity in areas that are able to mitigate heat islands by adding more greenery.

Some efforts to reduce flooding could include large projects to remove dams and other concrete infrastructure; others could be as simple as getting farmers to embrace reduced-till farming so soil can better absorb floodwater.

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This story comes to you from Sahan Journal, a nonprofit newsroom dedicated to covering Minnesota’s immigrants and communities of color. Sign up for a free newsletter to receive Sahan’s stories in your inbox.