Morganza

May 9th, 2011 by Editor B

Estimated Inundation

It’s been terribly dry here in Southeast Louisiana for a long time. In the midst of this drought, it’s hard to believe that the Mississippi River is riding at historically high levels. All that water is barreling down toward New Orleans. The US Army Corps of Engineers is opening the Bonnet CarrĂ© Spillway right now to divert some water into Lake Pontchartrain. More ominously, the Corps is considering opening the Morganza Spillway for the first time in 35 years. That would divert a huge amount of the Mississippi’s flow into the Atchafalaya River basin.

I’ve been wondering about the consequences of this. I understand it would put a lot of farmland under water. It would destroy crops and perhaps even livelihoods. These and other sacrifices are being considered in order to protect Baton Rouge and Louisiana. It must be an awesome responsibility to make a decision like that. I can only hope that all the people in my fair city consider the sacrifice others may have to make on our behalf. How will we conduct ourselves to show that this sacrifice was warranted? Oh wait, this is probably about capital more than human beings. Nevertheless I feel for those people who may be flooded for our benefit.

The ironic part is that the Mississippi actually wants to flow into the Atchafalaya. It would probably have made the switch a couple decades ago if humans hadn’t intervened. The American Rivers conservation organization posted an article yesterday, The Consequences of Controlling a River Course:

If the Mississippi River were to shift course, the effects would be devastating. Several cities would be inundated and might require relocation. Oil and gas pipelines throughout southern LA would rupture and commerce on the river and in New Orleans would be severely disrupted.

However, in ecological terms, the Louisiana coast would be revitalized. The western part of the Mississippi delta would receive the sediment and freshwater it has been deprived of for decades. Increased sediment distribution would reduce coastal erosion, and provide nutrient-rich sediments for terrestrial and aquatic habitat. Additionally, this would reduce Louisiana coastal wetland loss, which currently occurs at a rate of 1 acre every 38 minutes. The combined effects of these ecological benefits would ultimately increase the sustainability of Gulf Coast fisheries.

Something to think about.

And, while the Corps fiddles with control structures, I suppose there’s always the possibility that control could be lost, and the water will have its way. Who knows what will happen?

2 Responses to “Morganza”

  1. Brenda Helverson Says:

    The Control of Nature by John McPhee (1990), ISBN 978-0374522599, provides an excellent description of the challenges that the Corps of Engineers must face in preventing the Atchafayala River from capturing the Mississippi. After rereading it again, I remain convinced that, long-term, it is a losing battle.

    IIRC, this part of his book originally appeared as an article in The New Yorker .

  2. candice Says:

    I think Tim of the nameless blog can correct me on this, but the atchafalaya diversion has been so successful-as you know part of it is open all year-, and has built up so much sediment, while the mississippi channel has lost so much, that it is no longer trying to jump.

    Has to do with the steepness of the grade towards the sea.

Leave a Reply