Research Concludes Mississippi River Sediment Load Insufficient to Sustain Coastal Louisiana
The Mississippi River does not carry enough sediment through Louisiana to sustain much less restore coastal Louisiana. That has been my nightmare fear since I began studying this subject years ago. It has also been a theme of this blog and an important argument for the monetary liability of the federal government for the damage to coastal wetlands in Louisiana. Unfortunately, the situation may be even worse than I thought.
I have long believed that one of the most important causes of coastal land loss in Louisiana has been the construction of dams and slackwater navigation pools in the Mississippi River and its tributaries. The most significant of these tributary dam systems have been in the Missouri and Arkansas Rivers. These dams have all been built by the federal government with the most important built by the United States Army Corps of Engineers and additional dams built by the Bureau of Reclamation in the United States Department of the Interior. The construction of these dams has reduced the sediment load in the Mississippi River passing through Louisiana by over 50%.
Over the last year or so, I have traded a small set of email correspondence with Michael D Blum, a now former geology and geophysics professor at Louisiana State University. Blum has been conducting research on the amount of sediment carried by the Mississippi River and the river's potential for carrying sediment in the absence of the dam systems. His research is being published on Sunday June 28th in Nature Geoscience in an article entitled, "Drowning of the Mississippi Delta due to insufficient sediment supply and global sea-level rise." A fee is required for the purchase of the article. Blum's co-author is LSU professor emeritus of Oceanography and Coastal Sciences, Harry H. Roberts.
Sadly, this article concludes that even if the dams in the Mississippi River tributaries were removed, the rate of global sea rise would still more than offset the sediment deposit from the Mississippi River were the river and the coastal wetlands reconnected.
If this research is accepted as accurate, this leaves Louisiana with some rather stark and unpleasant decisions that need to be made. Some of the early decisions will concern what efforts will be made to reconnect the river to the wetlands and how will the limited sediment supply be allocated to sustaining some portion of the coast. Implicit in this decision is the question of what areas will be abandon. I again also raise the question of whether the federal government should be held financially responsible for the loss of the coastal wetlands in a court of law. A related judicial question concerns whether the federal government should be compelled to consider the impact on coastal Louisiana of actions in the management of the Mississippi River system including the tributaries far to the north of Louisiana. Numerous existing federal statutes would appear to require this consideration.
Congratulations to Dr. Michael Blum and Dr. Harry H. Roberts on the publication of their article and on the completion of his research.
