A Battle Against the Mississippi
Beautiful but deadly, we can see what she can do.
If only she could see her actions from our point of view.
We’ve created dams and levees and built walls of restriction.
The maintenance of her has become our life’s addiction.
Management has become a never-ending project,
Regardless of time, or money, or even the best architect.
Oh, she does give, but also takes away,
So we watch the water levels every hour, every day.
Should the costs versus the benefits of control be compared?
How do we make sure not to be once more unprepared?
We rely on her heavily to create our entire civilization,
But one raindrop too many calls for our evacuation.
So how long will it take to find the right answers?
When can we call ourselves achievers instead of advancers?
Beautiful but deadly, we see what she can do.
The Mississippi River, our society’s never-ending issue.
-Karmyn Cox
Levees: How They Work
Throughout an entire course of discussion on the Mississippi River Valley, the term levee came up a lot. We just briefly discussed them, and mainly focused on the history behind them. But how do they work? What are they made of? How are they maintained? Why do levees fail?
What is a Levee
Levees are man-made walls, typically made of sediment or cement. Earlier levees were made solely from dirt, and they are made to control flooding of bodies of water, as well as control the direction of the flow of water. Levees have been around in the United States since the early 1700’s, and they have been useful in the controlling of flooding along rivers.
Modern levees consist of multi-layered walls at different heights. This layering helps to control the flow of the water, especially if the water levels fluctuate a lot. These walls are either made of sediment or concrete, or in some cases, a mixture of both. Although the levee is a good way to control water flow, there are a few problems with them that have different solutions.
Problems with Levees
Levees are only designed to be built to a certain height and sometimes water levels will rise above this height, causing waters to flow over the top of levees and flood the land beyond it. This is referred to as height deficiency, and the simplest solution to this problem is either building the levee taller or adding in a flood wall at the top. This flood wall is typically made of concrete, and only goes a certain depth into the levee.
Another problem that levees face is stability. Since many levees are made of dirt, erosion sometimes breaks parts of the levees off, which in turn can cause the whole levee to fail and for floodwaters to move into land beyond the levees. Stability and erosion can be fixed by one of two ways: a rock wall constructed to strengthen the levee, or the flattening and widening of the slops of the levees. These methods have proven to be effective when dealing with these problems.
A very common problem that levees face is seepage. Seepage can occur at any height on a levee, and it occurs when water literally seeps through the sediment and slowly floods the lands past the levee. This is a very common problem, which is fixed by putting in a cutoff wall. This is done by digging a long trench along the levee and filling it with cement. This typically fixed the problem of seepage and was discussed in detail by one of our guest speakers. This process of maintenance is typically very effective in stopping seepage.
These are the main causes of levee failure, and as you can see there are many ways to maintain these levees and control flooding along rivers.
References
· https://www.youtube.com/watch?v=A1IxIKLV68E
SEDIMENT
Lou did not visit the New Orleans clubs often, her duties as the wife of a trapper in Plaquemines parish did not permit her. Someone had to cut up the gator and defend the house from the wild boar. In 1927 the New Orleans city government, owned & operated by the New Orleans banks in time of emergency, dynamited the levees below New Orleans and flooded Plaquemines parish. Lou had heard about it before the newspapers could have told her, as the river travelled faster than news that week. As the levees had confined the river, it had been starved of its usual diet of alluvial soil from the upriver floodplain. After the levees, the sediment comes in 20-year cycles it seems, and has added more than a few artifacts from the 20th century to its diet; petroleum products, neighborhoods built in swamps, and Lou and her neighbors. They will all serve as reminders of the war on water in the geological record of the Gulf of Mexico.
CGK