Oct 08, 2019

Sediment-Diversion System Created in Louisiana to Reduce Erosion

Louisiana is creating a sediment-diversion system in order to reduce inland flooding and erosion. 

Marsh

In an effort to reduce coastal erosion, Louisiana wants to build two river diversions that will redirect the water and sediment the river carries to eroding wetlands. 

Also known as the Mid-Barataria and Mid-Breton Sediment Diversion Projects, these diversions are meant to mimic a natural process, with the advantage of operating continuously for decades. In 2018, the U.S. Geological Survey estimated that Louisiana's coastal parishes lost nearly 2,000 sq miles between 1932 and 2016. 

The idea is to mimic the river's land-building process from the past, in which large quantities of sediment would be deposited after spring floods and by shifting course. Those processes ended 150 years ago when humans locked the river in its present channel and cut off spring flooding with levees, according to the New Orleans Advocate.

The Mid-Barataria Sediment Diversion will direct sediment, freshwater and nutrients from the Mississippi River into adjacent degrading wetlands in Barataria Basin, according to the Mississippi River Delta website. The project aims to maintain existing marshes and increase habitat resiliency to sea level rise and storm events. 

The Mid-Breton Sediment Diversion is expected to restore significant habitat in the Breton Sound Basin, such as fresh, intermediate, and brackish marshes. It will benefit marshes that have been sediment-starved since levees were built almost 100 years ago. The diversion will build and maintain almost 16,000 acres of new land in the Breton Basin during its first 50 years of operation.

“The fundamental problem in coastal Louisiana is that lack of sediment, and so we’re trying to mimic the way Mother Nature would have delivered that sediment to our coast in the past,” said Bren Haase, executive director of Coastal Protection and Restoration Authority, to the Associated Press.

These diversions are part of Louisiana’s Coastal Master Plan, which was created following hurricanes Katrina and Rita in 2005 in an effort to achieve comprehensive coastal protection and restoration. 

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