The second-worst flood in Minnesota's Rapidan Dam's 114-year history didn't destroy it, but it put it "in imminent failure condition." Now, a nearby bridge is at risk of collapsing.
What's happening?
Nearly two dozen Minnesota counties have been approved for federal aid under a major disaster declaration after severe storms brought record flooding to the state in June. The southern part of the state was soaked by 8 to 10 inches of rain over a three-day period in the middle of the month.
The flooding killed at least two people and forced the evacuation of hundreds from their homes. As the water from heavy rain made its way down the swollen Blue Earth River, it damaged the aging dam, located about 70 miles southwest of Minneapolis.
"We do not know if it will totally fail or if it will remain in place," officials said, per The New York Times. The dam's main structure seemed to hold together, but its integrity is still being assessed.
Why is the damage to the Rapidan Dam concerning?
The Rapidan Dam is one of more than 90,000 dams nationwide to receive a D, or mediocre, grade from the American Society of Civil Engineers. "Dam failures not only put the public at risk, they can also cost our economy billions of dollars in damages," the report said. "Failure includes more than the dam's damage, but can negatively impact many other infrastructure systems, such as roads, bridges, and water systems."
NASA research says the proportion of people on Earth who live in flood-prone areas has climbed by 20% to 24% since 2000. Vulnerable dams are coming under more pressure as heat-trapping gases warm our world, and the resultant changes in our climate raise the risk of flooding.
The Federal Emergency Management Agency reports that since 1996, 99% of counties in the United States have experienced a flood but just 4% of homeowners have flood insurance.
What's being done to prevent damage to older dams?
The Infrastructure Report Card from the ASCE calls for full funding of the national dam rehabilitation and repair funding program, increasing state funding for dam safety programs, and encouraging improved land use to help mitigate the problems faced by older dams.
Some cities are using new technology, such as roofs that act like sponges, to soak up rainwater. A Spanish startup is using emerging computer technology to create more accurate and powerful models to forecast flood risks better.
Technology that uses AI-based algorithms and advanced data collection techniques is being used in an ambitious project that produces augmented-reality photos of specific locations to show the impact of flooding.
Meanwhile, at home, planting a rain garden or growing native plants can help absorb water and protect your property from flooding.
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