The human race is responsible for its effects on the earth, but sometimes Nature takes a strong hand in changing our future.
The lower Mississippi River from the confluence with the Ohio is no long a natural river. It is a manmade water channel. There are levees and dams and control structures to make it go where we want it to go. One of the results is that the elevation of the bottom of the river has risen, almost to the point where the river is running down the top of a long hill from Caruthersville to the Gulf of Mexico.
With the massive floods now flowing down the river, no place is more critical than the place where the Mississippi wants to change its channel over to that of the Atchafalaya River a few miles above Baton Rouge. The Army Corps of Engineers have been fighting with the River at that point and built the Old River Control Structure in the 1960s. Then it built other dams to help control the flow to help the original structure. It was tested in 1973, but the upcoming test will be much more this weekend.
There is an excellent discussion of the Old River Control Structure on the Mississippi River at Jeff Master's blog in Weather Underground. I recommend you take the time to go read it
Back in 2004-5 when I was doing the final research on my novel Broken River, Alice and I drove up and down the river and over the Old River Control Structure itself (it carries the highway). We looked over the different structures the Corps of Engineers had built and read a lot of the material that was available at that time. The bit about how closely the structure came to failing in 1973 was well documented. It was because the Mississippi River had gouged out a huge hole over 100 feet deep right in front of the structure and was eroding away the sand and mud leading up to the floodgates, sort of like teeth losing the gum and bones that hold them in place.
We drove downriver following the Atchafalaya to see the alternate/preferred water-path to the Gulf of Mexico. The little towns below the structure on the Atchafalaya River were sleepy little communities, and there were orchards and fields all around. Lots of horses as I remember. The channel of the Atchafalaya itself was only about 100 yards wide. The levees were huge, especially when you saw them from behind. On the other side the Mississippi River is over a mile wide in low water season.
There is a scene in Broken River about a school bus taking kids on an outing and parked in the parking lot next to the sound end of the Old River Control Structure when the earthquake starts to shake the levees. The Mississippi is at flood stage, though I did not have it as high as it is now. But that shaking made muck and quicksand out of the levees and the underpinnings of the Structure. The pressure of the water simply moved the huge dam aside like a large door. The kids were alright, but marooned on an island surrounded by the River.
I have this niggling fear of what could happen if the earthquake of 200 years ago happened now as I described in my novels. My books would become instant best sellers, but the price to the country would be ruinous. But this could happen without an earthquake. We live in a dangerous time.
