In the study, researchers recount the re-alignment of the ancient and modern Mississippi River during the last 15,000 years.
Alexander County sits near the confluence of the Mississippi and Ohio Rivers, at the southernmost tip of Illinois. The sparsely populated jurisdiction is perhaps best known for devastating floods resulting from repeated failures of the Len Small levee in 1993, 2011, and 2016. Homes and businesses have been severely damaged, residents stranded, and rich agricultural land irreversibly degraded by sand deposition and erosion.
Despite the severity of past flooding, the levee has been left unrepaired since 2016, leaving the area to flood every year since. Residents, land owners, county officials, and area lawmakers are clamoring for the U.S. Army Corps of Engineers to repair the breached levee. However, a new study led by a University of Illinois soil scientist predicts the levee will continue to fail even if repaired, and more extensive intervention is needed to prevent future flooding.
“Because the levee is built on unconsolidated ancient Ohio River valley alluvial sediments, which are easily eroded by the Mississippi River, any patch or repair will only be a short-term solution. The levee is very likely to fail again during a future major flooding event,” says Kenneth Olson, professor emeritus in the Department of Natural Resources and Environmental Sciences at U of I.
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