Due to a personal grudge against the USACE I'd really like for them to lose their battle against the Mississippi River and realize they should stop and really think about how they mess with rivers and water supplies. But realistically what would it mean if the Mississippi decided she was tired of that wall and fucked it up?
If the Old River Control structure fails, a sequence of things will happen.
First…we already know that if that happens…there is nothing we can do to shift the river back to its old bed. Nothing. The Army corp of Engineers has admitted it. Engineers who study such things have admitted it. Such a thing is beyond our ability. If the Mississippi carves a new channel for itself, that’s it. We learn to live with it, period end of sentence.
The most immediate thing would be that the Atchafalaya river ceases to exist. The moment the Mississippi jumps to the Atcafalaya’s channel, it’s the Mississippi. It will be until the Mississippi jumps channels again. Every town and person along the current course of the Atchafalaya is in deep, deep trouble, because a flood’s a-coming, and there is no power of humans that can stop it. All people can do is get out of the way.
The old channel will become a bayou. And now that the force of the river isn’t pushing out to sea, the salt water will infiltrate back up the much, much smaller distributory stream that will be left.
Remember Baton Rouge? Remember New Orleans? They’re gonna lose the main source of their fresh water. Both are tidal salt marshland now. New Orlean’s port is high and dry and useless. Ships full of exports and imports are stranded, and the marine shipping industry for the Midwest is hamstrung just like that. Farmers cannot ship produce out. We cannot ship goods in, because there is no longer a facility on the Mississipi that can unload marine cargo. Billons more is lost, possibly trillions. The only thing to be done is move, people and industry both.
New Orleans and Baton will empty out, in all likelihood. Without fresh water, people will have to relocate. In a decade, they’ll be ghost towns, and eventually the swamps will reclaim what’s theirs.
There are a terrible lot of industrial plants built along the Mississippi near New Orleans, because they cannot run without a source of fresh water. They’re all useless once the Mississippi abandons them. Billions upon billions of dollars, left high and dry and unable to run. Billions more in production lost.
Rice farms drown or go high and dry. Commercial oyster beds around the Atchafalaya die because there is now too much fresh water. Soybean fields drown.
Now, this is of course all completely natural. The wildlife will adjust. It has before, every time the Mississippi changes beds. This is normal. It’s natural.
But for the humans that built their lives in its way without thinking forward, because with our little mayfly lives the river seems a static thing, unchanging…
Disaster isn’t really the proper word, because there’s been nothing of this scale before. Something greater would be needed to describe the lives and livelihoods ruined.
But despite that, it’s gonna happen. Sooner or later, it’s gonna happen.
Further reading that may interest you;
https://www.newyorker.com/magazine/1987/02/23/atchafalaya
https://www.nola.com/environment/2017/12/rising_river_bottom_could_swit.html
