Letting Mississippi run its natural course could save New Orleans from hurricanes
The full diversion of the Mississippi River back down the Atchafalaya basin would flood millions of acres, permanently submerge entire communities, destroy oil refineries and farms, and leave the port of New Orleans without its river. But it could also save Louisiana from the next hurricane.
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New Orleansians consider the breaking of the river levees to be the ultimate disaster that could befall their city. The full force of the Mississippi would fill up the underwater bowl in which New Orleans lies with far more force and water than filled the city when Lake Pontchetrain burst it’s levees after Katrina. The last time that almost happened was during the great flood of 1927. As rain fell and flooding developed at an alarming rate, New Orleans businessmen convinced the federal government to dynamite the levees in nearby Plaquemines Parish to avoid further drowning the citySkip to next paragraph
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As it turned out, breaking the levees submerged and destroyed all of Plaquemines Parish, leaving over 6,000 people homeless, though each was given the unseemly paltry sum of $169 each for his losses.
Like trying to hold back the tide
It is obvious the Army Corps of Engineers could not let such a disaster happen again. They have already opened the Bonnet Carre spillway, which is now bleeding muddy Mississippi waters into Lake Pontchetrain, just north of the city. And as flood waters continue to rage and the prospect of future flooding looms large for the city, New Orleans residents worried: Was such a diversion enough? But the Corps had an $18 billion trick up its sleeve.
For thousands of years, the Mississippi River has naturally writhed back and forth like a water hose, spewing muddy sediment loads first one place then another along several hundred miles of coast. These movements built up a number of major deltas along the southern Louisiana coast.
This shifting geography has gradually reoriented the course of the river. Now the river is running about as far east as it can possibly go, and it wants to writhe back west, away from New Orleans and down the Atchafalaya River Basin instead.
But in the late 1950’s, Congress passed a bill to save the port of New Orleans by making it illegal for more than a third of the Mississippi to flow down the Atchafalaya River basin. This is akin to passing a bill to hold back the tide.
A tale of two rivers
Today, the equivalent of seven Niagara Falls tumbles down from the Mississippi into the Atchafalaya River, making the Atchafalaya the second largest river in the country. A gunboat patrols the area in case some barge breaks loose and crashes into the dam holding back the two torrents, which desperately want to embrace. In 1937, the dam almost broke, sending engineers screaming into the night. The dam shook so severely that coal in a nearby railroad car ignited from the vibrations. After the flood, engineers discovered the river had scoured out a 100-foot deep hole in the water at the foot of the dam.
Since then, the Army Corps has made an $18 billion bet that they can prevent such a break – and the unplanned disastrous flooding that would follow – from happening again. The dice were thrown last Saturday when the Corps started carefully opening the Morganza Spillway to relieve pressure both on the levees of New Orleans but also on the old river control structure that separates the two rivers. The plan is to continue opening the spillways gate by gate until close to a quarter of the flow of the Mississippi flows down the Atchafalaya.