Humans have attempted to harness the great Mississippi River for nearly three centuries,
but just how successful have we been and are we making things worse?
Hey Guys.
Julia Here for DNews
As the world warms up and changes weather worldwide, many places like the US and the
UK will see more severe storms and without a doubt, more flooding.
But climate change isn’t the only way humans have made flooding worse.
We’ve been doing that for years.
Basically the best example comes from John McPhee’s 1987 New Yorker article “Atchafalaya”
about the attempted control of the Mississippi River.
Basically it goes like this.
The Mississippi always wants to find the shortest and easiest path to the Gulf of Mexico.
And every thousand years or so, it switches paths or “jumps”.
And these can be BIG jumps, like anywhere from Texas to Florida.
For the past century or so, the river has been itching to switch from its current course
to the Atchafalaya, which would essentially cut off the entire current Delta and all of
New Orleans from the river.
Which of course is not good for the loads of people who live there and the commerce
that depends on it.
So the Army Corps of Engineers took on the task to tame the river.
They built Old River Control Structure to limit the take of the Atchafalaya to 30%.
But rivers flood.
That’s just what they do naturally.
Water evaporates from the ocean, lakes, rivers, forms in the atmosphere and comes down as
precipitation, that’s basic.
And some years it doesn’t rain, it pours.
And when that happens a river will leave its banks and flood the surrounding areas.
This is natural and normal.
And sometimes happens every year like the Nile River.
But ironically by building control structures, like levees and dams, we’ve restricted the
flow of the water, make it faster, stronger, and more prone to flooding.
Rivers do this naturally too, as the river erodes its banks, sediment deposits on the
bottom of the river, and constricts it.
Like putting your thumb over a hose nozzle, it only increased the force of the river.
To make matters worse, more water reaches the rivers than ever before thanks to increased
construction over the past 50 years of things like developments and parking lots, all these
flat surfaces drain straight to the river rather than dissipating into riparian zones.
This can lead to the perfect storm.. or flood.
This combination lead to a disastrous (Catastrophic) flood in 1973, that nearly destroyed Old River
Control.
After heavy snowfalls the previous two winters, and more rain in the spring lead to the most
water in half a century to flow through the river.
Many cities along the river saw waters above flood level for more than 50 days.
In total the flood caused over 250 million dollars worth of damage.
A report published in the journal Science concluded that the flood was man-made.
And warned that more river constricting and levee building would only make problems worse.
Since then two more floods rivaled and even surpassed the 1973 flood.
The Great Mississippi flood of 1993 killed 50 people and caused 15 billion dollars worth
of damage.
It flooded 30,000 square miles and some places were flooded for 6 months.
A flood in 2011 put Old River Control to its greatest test yet.
Thanks to heavy snow and rain the previous winter, that summer the Mississippi Valley
was flooded for months.
The breech of levees in Missouri, Arkansas, Mississippi, and Tennessee forced thousands
to flee.
And farmland was destroyed thanks to chemicals released into the floodwaters.
So we haven’t exactly learned our lesson.
What to do about it?
Well we certainly can’t move elsewhere.
More people live in the Floodplains than ever and relocation plans costs millions of dollars.
We could build more levees but the levees that do exist haven’t been properly maintained
and really, they might wind up making things worse.
Jeffrey Mount, director of the Center for Watershed Sciences at the University of California,
Davis, said that “The dark secret that no one wants to share is that there are two kinds
of levees: those that have failed and those that will fail”
Some suggest using floodplains as fertile farmland, not cities.
And building strategic overflow system (or “flowage easement”) into a levee.
That way they could be open more often and water could flow onto farmland, and the government
would compensate the farmer for any losses.
Some suggest using wetlands as natural buffers.
Other plans include modern technology to better
understand flooding.