A massive restoration scheme in Louisiana contemplates the diversion of water from the Mississippi river in the hopes that the sediment it carries will settle and protect the coast from erosion, reports Associated Press.
In the past, flood defence structures to protect communities along the banks of the Mississippi stopped the natural land building process that built south Louisiana over thousands of years. As a result, coastal marshes are disappearing, leaving the area vulnerable to sea level rise and eliminating a natural buffer for hurricanes.
Furthermore, in 2010, the Deepwater Horizon oil spill – the largest accidental oil spill in world history – resulted in the oiling of more than 1,100 kilometres of wetlands, most of them in coastal Lousiana. The wetlands in the Barataria Basin estuary were the most heavily impacted. The oil spill and response accelerated the ongoing trend of coastal land loss.
Now, the Mid-Barataria Sediment Diversion project contemplates a large-scale sediment diversion to reconnect the Mississippi River to Louisiana's Barataria Basin estuary and re-establish historic delta processes by allowing for the controlled release of water, sediment, and nutrients from the Mississippi River, supporting ecosystem-scale restoration of the estuary. The project involves building gates South East of New Orleans to divert water from the Mississippi river and a conveyance channel complex. The U.S. Army Corps of Engineers estimate the project will lead to the creation of 21 square miles (54 square kilometres) by 2070, although subsidence and sea level rise are expected to cause the loss of some of the land built by the diversion.
The project poses some environmental and economic problems, though. There are environmental costs related to introducing non-salty water from the river in areas where animals live in salty or brackish water, including dolphins, fish and sea turtles, as well as shrimp and oysters, which have led fishermen and harvesters to oppose the project.
State officials believe the project, which mimics natural processes, is a first-of-its-kind: “Quite frankly I’m not aware of one on this scale anywhere in the country and there are few in the world that can match the size of this project”, said Gov. John Bel Edwards. The innovative coastal habitat restoration project, at a cost of nearly $3 billion, will be funded with settlement money from the Deepwater Horizon disaster, the largest environmental damage settlement in United States history for a total of $20.8 billion.
