USA: New model shows towns on the wrong side of an Illinois levee district are treading water
By Lisa Song, Al Shaw, Patrick Michels and Alex Hee
For years, the residents of Pike County, Missouri have blamed their worsening floods on their neighbors across the Mississippi River in Illinois.
Ever since the Sny Island Levee Drainage District raised its levees above authorized heights, Pike residents claimed, the agricultural lands behind the Sny were spared while farms in Missouri, protected by lower levees, were inundated.
The kind of science needed to prove allegations like this is expensive and time consuming. But thanks to a new government model, the Missouri residents finally have some science to back up their suspicions.
The Army Corps of Engineers designed a $500,000 computer model that lets scientists simulate how floods affect the Upper Mississippi River, demonstrating, in part, the difference that larger levees make. The tests show that if the region faces a disaster as grave as the Great Flood of 1993, communities with higher levees — found in a handful of levee districts on both the Illinois and Missouri sides of the river — would be far better protected, and those without them would fare far worse.
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It’s for this very reason that the Corps regulates levee heights. Levees are designed to prevent rivers from overflowing, but they create a zero-sum game where raising levees in one area can push extra flood risk onto others.
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