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Will The Mississippi River Flood More Because of Climate Change?

By Jeffrey Hess | Published 31 May 2011 04:18pm | comments
A flooded home near Vicksburg.

This year's Mississippi River flood set new records from Tunica to Natchez, but floods of this magnitude could become more common. MPB's Jeffrey Hess reports that global climate change and the river levees could make future floods more frequent and worse.

Melt from a heavy snowfall up river and record April rain fall along the Ohio River created the flood that is currently soaking Mississippi.

Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research, says there is more moisture in the air because of global climate change....that leads to heavier snow falls and more extreme rain.

"We have had major floods along the Mississippi in 1993, in 2008 and now again now. And they are all called 500 year flood, and how is that? Well how it is, is because the climate is changing and what used to be a 500 year storm is no longer a 500 year storm. It is more like a 50 or 70 year storm," Trenberth said.

A recent report from the International Energy Agency found that global carbon dioxide output, a key green house gas, set new records with more than 30-gigatons of carbon released.

The river has been greatly altered by the extensive levee system, making it run straighter, more narrow, and faster.

University of Southern Mississippi Geology professor Frank Heitmuller says the levees increase the water flow, upping the odds of a levee failure and trapping tons of sediment between the banks.

"We could be exacerbating the very bad effects of a flood and actually limiting the area in which it can spread out by this phenomena occurring of sediment building up and making the area between the levees higher and higher," Heitmuller said.

Heitmuller thinks we could see more intentional, controlled flooding such as at Cairo, Illinois during future floods.

Still, the levees also protect much of the state from regular, devastating floods and improve commerce.

Peter Nimrod with the Mississippi Levee Board says did the levees proved their worth in the face of historic levels of flooding.

"All these different factors that have all come into play this year for a monumental historic flood. And really it is great to see everybody come out of this thing ok. So it is wonderful to see the whole system work as a whole. Nobody failed. The whole system worked as designed," Nimrod said.

The flood is not yet over, and the is a chance that more heavy rain fall or an early tropical storm hitting Mississippi could cause the river to rise and flood again.


A flooded home near Vicksburg.



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