Flooding along the Mississippi River

A post by Anne JeffersonIn case other events have crowded it out of your news feed, there’s record-breaking flooding going on in the Mississippi River basin. Snowmelt in the headwaters, combined with weeks of heavy rains in the middle reaches of the river basin, have pushed the system to its engineered limits. The Mississippi River basin is home to more than 100 million people, and when the water flows past Natchez, it’s carrying flow from 41% of the contiguous United States, making it the third largest river basin in the world. The volume of water carried by the Mississippi River in flood can be measured in the same unit as ocean currents — within the next few days, the Mississippi River at Natchez will be flowing more than 2 Million cubic feet per second.

Flooding at the junction of the Mississippi and Ohio Rivers, 3 May 2011, NASA image

Flooding at the junction of the Mississippi and Ohio Rivers, 3 May 2011, NASA image

Start here

For hands-down the best analysis on the flooding, the engineering, the politics, and the media coverage of the flooding, you need to turn to Steve Gough’s Riparian Rap blog. Go there now to get caught up. Then when you want some other perspective, check out the links and resources below.

General information on the flooding

Floodways doing what they were designed to do

Edge of the inflow section, Bird's Point floodway. image by the US Army Corps of Engineers

Edge of the inflow section, Bird's Point floodway. image by the US Army Corps of Engineers

Early in the week the big Mississippi news story was on the opening of the Bird’s Point Floodway in Missouri. Media reports tended to focus on the sensationalist “us vs. them” people stories, with most of the stories completely missing the fact that the floodway was designed for this purposes and residents in it had known about and been compensated for its existence. Steve Gough had great coverage, including this piece.

The next big to-do will be over opening the Morganza floodway in Louisiana, expected to happen on Thursday 12 May. So far, the news media seems to be taking a bit more reasonable perspective here, but I expect there will be hysterical stories as well. My two cents: Based on experience with devastating past Mississippi River floods, our national policy has been to design and designate floodways to relieve pressure on levees on the mainstem of the Mississippi River. This means that some people miles from the main river will lose homes and property (and have been compensated for that risk), but it is for the benefit of much larger populations. Further, the areas that lie in floodways are part of the natural floodplain of the Mississippi River, and they would flood much more frequently without the levees.

More information on Bird’s Point and Morganza floodways can be found below.

Background Reading

1927 Mississippi River flooding, image from the Library of Congress

1927 Mississippi River flooding, image from the Library of Congress

The best general background information on floods and flood control on the Mississippi River can be found in John M. Barry’s book “Rising Tide: The Great Mississippi River Flood of 1927 and how it Changed America” and John McPhee’s essay on the Old River Control Structure in The Control of Nature, available on-line through The New Yorker.

Categories: by Anne, geohazards, hydrology, Uncategorized
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Comments (5)

  1. george.w says:

    This will keep me reading for a while! Also XKCD has a great post up today about the Old River Control Structure http://blog.xkcd.com/2011/05/08/michael-bays-scenario/

  2. Ann Willis says:

    Thanks for all the info. I haven’t waded through all of it yet, but plan to do so.
    FYI – today I drove by the Red River in Shreveport, LA. The river hasn’t been able to drain into the Mississippi like it usually does and is backing up. Already the water has gone over the banks in some spots. Back in 1927 the Red River also flooded due to the flooding in the Mississippi River and the water backing up into the Red. They do have an extensive levy system that was put in place after the flooding in 1927, and hopefully the levies will work as planned.
    The unusual thing is we’ve had a very dry Spring and people are not thinking about the Red River flooding. We haven’t had any rain since that storm cell came through – April 27, and people are complaining about how dry everything is. This is a very bad condition to have because if it does rain the ground is so hard it just runs off and does not soak into the ground. Now there is no place for the run off to go. I just hope we do not get any rain until the Mississippi River finishes cresting.

  3. Dear Ms Jefferson,
    My 6th grade science class is following the flooding as it progresses down the rivers and your article will help them tremendously. I can’t tell you how much a teacher like me appreciates the work you’ve gone thru to post all this information and how much it makes the science come alive.
    You are doing so much to foster interest in this kind of real-life, current events science by blogging like this and helping kids see that science isn’t just in the textbooks. It’s out in the world…everyday.
    Thank you so much and we’ll keep reading.


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