Living Shoreline Demonstration

Opportunity

Some 29 miles southeast of New Orleans lies the Biloxi Marsh estuary, a network of coastal wetlands totaling about 210,000 acres. In addition to the Biloxi Wildlife Management Area located there, the wetland helps protect the city from storm surges.

Over time, lack of bank stabilization caused the width of the Mississippi River–Gulf Outlet Canal (MRGO) to expand in some areas from 498 feet to 2,700 feet. Saltwater intrusion from the MRGO affected the Biloxi Marsh, and the building of levees along the Mississippi prevented the marsh from being replenished with river sediment.

Solution

The Louisiana Coastal Protection and Restoration Authority was interested in constructing a demonstration project that utilizes living shoreline solutions. We analyzed 21 miles of coastal fringe to develop an understanding of shoreline change rates, morphology, and coastal processes.

We then evaluated nine living shoreline concepts based on structural stability, shoreline protection performance, cost, and constructability. Using 3D computational fluid dynamics or CFD modeling tools, our engineers analyzed these alternatives to determine their ability to reduce wave energy as it passes through the structure.

Outcome

The project will provide self-sustaining protection to almost three miles of shoreline in St. Bernard Parish, reducing erosion and moderating the impact of waves and storm surges. It will stimulate the growth of oysters and increase biodiversity in the area.

Oyster reefs filter and improve the quality of seawater, provide nursery habitat for fish and shellfish, provide food for predatory fish such as flounder, drum, and speckled trout, and mitigate nutrient loading, eutrophication, and hypoxia.