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Memories of the 28th Century

The Next Great Flood of the Mississippi

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A number of years ago, I read about the relocation of the mouth of the Mississippi River, the Old River Control Structure, and related matters, and I concluded that the Mississippi would relocate someday, and it would have huge economic effects on the U.S.A., especially the great Plains and agriculture commodities. It hasn't happened, yet, but it is inevitable. With a huge amount of money could be invested in constructions that would minimize the dislocations and economic problems, but that investment would be greater than the losses that will result from the change in course.

I was thinking about making a blog post about this problem, but there isn't much that can be written about it, except to restate the essential facts, and those facts are widely known. Knowing the facts doesn't change anything. It's like knowing that the Sun will go nova in 10 billion years, or something like that. It is interesting, but it is far off, and I can't do anything about it. People have known about the relocation of the Mississippi for decades, but nothing can be done about it, even though it was accelerated by human activities. It is almost funny, but by clearing the snags and deadwood in the Red River and the Atchafalaya Rivers the path to relocation was cleared. After those rivers were cleared, the Atchafalaya progressively took more and more water from the Mississippi, until the Army Corps of Engineers built the Old River Control Structure to limit how much water can flow from the Mississippi into the Atchafalaya to 30% of the Mississippi's flow.

That worked for a little while, but in 1973 there was a flood that damaged the control structure and almost changed the river's course. So the Corps repaired the control structure and added related defenses. The river hasn't changed course, yet, but ti's just a matter of time. The river in the lower stretches rises every year, because sediment falls to the bottom and raises the riverbed. If this interests you, then read the Wunderground article that is linked below. The availability of that article is why I haven't gone into detail about the problem in the past, it has already been covered.

My thoughts on the change in the Mississippi is that the economic fallout from the relocation will make the actual fact seem small. The amount of agricultural goods and industrial products that come down the Mississippi is staggering. The question is whether it would be possible or economically feasible to stop the river from changing course. I can picture several cubic miles of fill creating a ridge between the Mississippi and the Red and Atchafalaya rivers. It would be a multi-billion dollar job that would make the Great Wall of China look like child's play. The ridge would have to run from North of the present structure for tens of miles South of that point.

The construction is possible, but it may not be economic to build it, and it would simply put off the inevitable relocation to a later time, when it would be even more devastating. In retrospect, it might have been better, if Shreve allowed the river to continue in its original bed back in 19831 and let nature take its course. The effects would have been milder and recovery would have been quicker, but it's too late for that. We can't prevent the river from changing, but it might be a good idea to plan for it, and have people stop making the problem worse by building in the lower delta. It might even be a good idea to start thinking about building a replacement city somewhere in the region where the river will meet the sea.

There are things that people can't do effectively, and the relocation of the Mississippi might be such a thing. The bed of the river rises several inches per year, and that means that floods that are equal in volumn become more severe with each passing year, and climate change has nothing to do with it.

A very good three part article about the history and future of the Mississippi, and this has recent updates, because the 2019 flood was almost the one final flood.