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Disasters & Extreme WeatherScience

Diverting the Mississippi to Revive Wetlands

The recent flooding of the Mississippi River has created an unexpected boon for the wetlands around the city of New Orleans.

Dr. James Morris, director of University of South Carolina’s Belle W. Baruch Institute for Marine and Coastal Sciences near Georgetown, South Carolina, notes that the wetlands around the city of New Orleans are disappearing at such ar ate that, byt the end of this century, there will be very little left of the marshlands.

“At some point New Orleans is going to be an island in the Gulf of Mexico, surrounded by levees.”

“The basic problem here is the wetlands around New Orleans are not getting sediment like they once did because the river has been altered to prevent flooding,” Morris said. “Navigation is really important here, and they have protected navigation at the expense of the wetlands.”

Because of all the canals, levees and dams built along the Mississippi River to control flooding, as well as to make waters easier for ships to navigate – purely human concerns – the flow of the Mississippi River sediment has suffered dramatically, and this is a real concern for those marshlands which are fed by the river. The lack of nutrient-rich sediment being brought down the river to the marshlands is accelerating the loss of the wetlands along the Delta, Morris says, and without the wetlands acting as a coastal buffer against floods and soil erosion, not to mention the habitats they provide for fish and wildlife, there are going to be long-term impacts.

“I’m more involved in the technical aspects of how you go about restoring the marshes. One of the solutions is to divert river flow from the Mississippi into the surrounding bayous,” Morris said. “That’s probably the only feasible solution.”

And that’s just what the U.S. Army Corps of Engineers have done during the recent flooding of the Mississippi River, as they opened two channels to divert part of the Mississippi River away from New Orleans and through the floodways towards the wetlands.

The Bonnet Carre spillway is sending water into Lake Pontchartrain, while the Morganza spillway diverts water through the Atchafalaya River Basin and into the Gulf of Mexico.

As a result, the starving Delta wetlands are fed with the much needed sediments that they need to grow and thrive, while only a thousand or so humans are affected.

“But the question is, ‘Do you flood a city of a million people or do you flood 1,000 homes in a floodway?’ The answer to that one is pretty easy. That was designed from the get go. People who lived there knew that was going to happen,” Morris said. “Yes, it’s a tragedy for some people, but no one died, no one lost their land. They’ll rebuild. And the city of New Orleans survived.”

So maybe there’s a lesson to be learned here: live in balance with nature, instead of trying to make nature live in subservience to you.

Source: University of South Carolina
Image Source: mokolabs




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