He just keeps rolling along … or does he

The lower reaches of the Mississippi River thrive in American song and story, in legend and tall tales, carrying the imagination of millions of school children (and adults) on a free-floating raft past plantations and swamps. North America’s grand river flows through southern Louisiana past the state capital, Baton Rouge, and past New Orleans into a low-lying delta it has built over thousands of years. But the Mississippi, maybe he’s sick of livin’ and scared of dyin’, ’cause he wants to change his course in a continuing quest for a shorter route to the Gulf, a quest that engineers have been working for decades to thwart because it would leave industrial plants, the state capital and the cultural capital of Louisiana on a riverine backwater. The problem began with engineers’ well-intentioned assaults on the Mississippi and on a prehistoric logjam in the Atchafalaya River, which flows south through central Louisiana, opening a can of Mississippi fishing worms that no one could have foreseen.
About 30 percent of the Mississippi’s water flows into a channel called the Old River, part of a former broad loop called Turnbull’s Bend that added many miles to Mississippi river travel. In a program designed to shorten and straighten the river, a channel was dug in 1831 that eliminated the bend by rerouting the Mississippi through its narrowest part, where the river had nearly doubled back upon itself like a hairpin turn on a mountain road. Engineers short-cutting the meander hurried along a classic stage of river evolution in which the river makes an ever-lengthening meander — like a man who enters a hardware store to buy a part for the washing machine and takes a side trip up the power tools aisle and back down the socket aisle, eventually returning to the main aisle after a delightful detour — and eventually cuts across the narrow piece of land.
Before the 1830s, the extreme western bend of the meander accepted the Red River from the north and sent a small amount of water to the south via the Atchafalaya in an unusual case of a river sending water away from its main stream rather than gathering all tributaries into its ever-growing channel. After 1831, the Mississippi quickly widened the new channel, the meander’s northern leg mostly dried up, and the southern leg of the meander, connecting the Red and Atchafalaya to the Mississippi, was dubbed the Old River. The second step occurred when the state of Louisiana in 1839 blasted away the 30-mile log jam, which had blocked river travelers headed for western Louisiana and Texas.
With the logjam clear, the Mississippi somehow sensed that it could find a shorter route to the Gulf of Mexico by transferring its burden to the Atchafalaya, because rivers, like people, prefer the direct route once they quit all that meandering and settle down to getting the job done. The Atchafalaya was flowing free for the first time in thousands of years, so the Mississippi began sending large quantities of water to its country cousin, and by the 20th century hydrologists realized that in a short time the Mississippi would reroute itself. “The more water the Atchafalaya takes, the bigger it gets; the bigger it gets, the more water it takes,” said Fred Bayley, chief engineer of the Lower Mississippi Valley Division of the Corps of Engineers, in the book “Flood,” part of Time-Life’s “Planet Earth” series.
In 1954 Congress empowered the Army Corps of Engineers to institute the Old River Control Project to prevent the Atchafalaya’s capturing the entire flow of the Mississippi. The project, a massive series of spillways, floodways and levees, was put into operation in 1963. The Corps doesn’t want to eliminate all flow through the Old River because agricultural and marine development depend on the Atchafalaya, so it maintains a 30-percent diversion, and maintaining that balance requires continuous monitoring of the rivers and increasingly complex bulwarks against the rivers’ natural tendency. The flood of 1973 damaged some of the structure, and in 1980 the Corps began building an auxiliary control.
But Johnny Cash could have been describing rivers when he said, “You put the screws to me, I’m gonna screw right out from under you.” The Mississippi wants to join the Atchafalaya, and it’s possible some of us in our lifetimes may see a historic course change, not the first in the river’s long and storied history. “It’s going to happen,” said Raphael Kazmann, professor of civil engineering at Louisiana State University, in “Flood.” “We can delay it, but ultimately the river will take over. In the long run, man cannot win.”

This entry was posted in Geography, Science and Nature. Bookmark the permalink.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s