Flooding Rivers: How to Go With the Flow

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The solution to more frequently flooding rivers in the Midwest isn't to fight it with more and higher levees, but to flood more land, say ecologists and water managers. The record floods along major rivers of the U.S. Midwest don't have to be disasters and can be turned into opportunities to benefit many native plants and animals while saving towns from floodwaters.

The accidental over-topping of one particular levee last week along the Illinois River has given The Nature Conservancy and researchers an opportunity to study just how the deliberate flooding of some lands might be the solution.

“We're just seeing this record breaking floods over and over again,” said Michael Reuter, director of The Nature Conservancy's North America Freshwater Program (see his video blog). Climate scientists have long predicted as much, he said. “The 100-year flood will happen more frequently than that name would suggest. It's time for a different approach. We can't keep building higher and higher levees.”

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The Illinois River itself tried a different approach when it spilled about 2 billion gallons of water into the Emiquon Preserve last week. That prompted the preserve managers to wonder what would happen if they had a floodgate on their levee and had deliberately let in a lot more water?

“We could reduce flooding nearby by several inches or several feet,” Reuter said.

A similar benefit was observed when a levee failed at another Nature Conservancy preserve at Spunky Bottom on the Upper Mississippi in 1993, said water resources researcher Richard Sparks of the University of Illinois. The benefits for nature are that the deliberate flooding can mimic seasonal moderate flooding events, to which many native species are adapted, he explained. These same species are struggling with the epic floods now underway, which have little in common with the floods they evolved with.

“There is a difference between seasonal floods and these,” said Sparks. “These bigger floods are less frequent like we are having now on the Illinois River. They help some species and hurt others. In all these (preserves) what we are trying to do is recreate natural flooding regimes." That's important because the natural regimes have already become distorted by climate change, he said. On the Illinois River water levels are much more erratic than they were naturally.

By seasonally flooding nature preserves – as well as farmland, where farmers have agreed to it – both excessive flooding and drought conditions can be moderated, Sparks said.

The plan would cost money of course, but Reuter argues that's really beside the point since the cost of flood damages to towns and river commerce are already astronomical.

“The question is not whether we spend money, but are we spending it wisely,” Reuter said.

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