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Memories of the 28th Century

Water Works

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Humans have been accused of having damaged the Earth in some ways, but the major alterations that humans have made to the Earth have been largely ignored, while trouble and noise has been put into climate, which is a perfectly natural thing, and while it is normal and natural for rivers to change courses, it isnít natural for them to run on the high ground while a lower course is immediately available.

People have been altering rivers to suit them for more than six thousand years. The Tigris and Euphrates were being tapped for irrigation before the first historic record of cities in Mesopotamia, and the Nile River was also being tapped for irrigation that long ago. Those early irrigation schemes did not alter the rivers much, but by 2000 BCE there was a system of canals that fed water to cropland and drained the land to prevent salt build up. The water was drained into a canal that ran between the two rivers and emptied into the marshes South of Mesopotamia. That system remained in use until it was destroyed after the Mongols invaded in the early 13th century CE. Before the Mongol invasion, that region was home to a larger population than live there now.

There have been other major reroutings of rivers. Rivers in the Netherlands have been channelized and directed for about a thousand years, and larger areas have also been reclaimed form the sea. But I started writing this because of the work that has been done to the Mississippi River and nearby rivers. For about two hundred years people have been straightening and cleaning up the Mississippi. Most of the work has been done to make it more navigable, and it has succeeded. Most notable was Henry Miller Shreve, who opened the rivers to navigation with better steamboats, and the elimination of snags, collections of dead wood. The snags were so bad in the Red River that it was called the Great Raft and was 150 miles long. After he succeeded, the City of Shreveport was named for him. He also cleared the Atchafalaya River, which was almost as clogged. Without his work, the Mississippi wouldnít be able to carry nearly as much freight as it does. but by clearing the Red and Atchafalaya Rivers, he allowed them to take some of the water from the Mississippi, and over the course of time, it was taking more than 30% of the flow of the Mississippi, and it appeared to be increasing its share. That wasnít surprising, because the riverís mouth had moved back and forth along the Gulf Coast through the centuries, and it naturally sought the easiest path, and it drops sediment to fill its bed and adjacent areas. The Atchafalaya has a shorter, steeper course from central Louisiana to the Gulf, so the river should naturally use that course, but starting in the 1950ís the U.S. Army Corps of Engineers built a collection of dams and locks to keep the rivers in their present locations. In the 1973 flood part of that was washed out, but the river didnít change course then, but it was close. Since then the Corps installed the Morganza Spillway and various other flood protection works around New Orleans. The Morganza Spillway is designed to take pressure off New Orleans in case of floods, but it has only been opened twice.

Right now the Mississippi is in flood from Iowa South, and it has been in flood for months, and this weekend Hurricane Barry hit the Louisiana coast, coming ashore at Morgan City, where the mouth of the Atchafalaya is, and significant rainfall is expected. This is the kind of situation that could cause a flood that would break the Old River Control Structure or the Morganza Spillway, and either event could cause the Mississippi to change its channel; although opening the spillway might take pressure off the control structure.

Whether it will be Tropical Storm Barry or some future event is irrelevant. Humans messed up Mother Natureís design of the Mississippi River, and one of these days the River will move to where it wants to be.

This situation came to mind, because it is something that humans actually did, and it will produce a real disaster, but it is barely reported by the press, while climate change is a natural thing that may or may not cause major problems; irhasnít yet, even though dire results were predicted for past years but didnít happen. Humans could still mitigate damage from controlling the River, but there would be major problems with transportation. A huge amount of produce and manufactured goods use the Mississippi for transportation. There are railroads, but more goods move on the river than rails could handle. and it would take years for the new river to be able to handle the traffic.

There is little that could be done to avoid the river moving, so we should just think about how to work around it.

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