Feasibility Analysis of Shore Protection Alternatives for Rockefeller Wildlife Refuge in the Chenier Plain of Southwestern Louisiana (USA)

Portions of the Chenier Plain coastline of Southwestern Louisiana are receding at an average rate in excess of 12 meters per year, resulting in the loss of a significant amount of coastal wetlands. The shoreline between Joseph Harbor and Beach Prong, approximately 15 kilometers, in the Louisiana Department of Wildlife and Fisheries Rockefeller Wildlife Refuge has some of the highest erosion rates in the region. The coast consists of shell hash and sand beaches perched on under-consolidated, clayey marsh deposits that erode rapidly in response to normal wave conditions and episodic storm events. The National Marine Fisheries Service and the Louisiana Department of Natural Resources funded a feasibility study and alternatives analysis under the Federal Coastal Wetlands Planning, Protection, and Restoration Act. The project has a stated goal of halting net shoreline erosion which would result in the protection of approximately 350 hectares of wetlands. Proposed alternatives included offshore breakwaters, sand placement, revetments, and geotextile structures. The structural, geotechnical, and environmental feasibility of each alternative was considered along with a constructability analysis. These criteria were used to select alternatives for further analysis; a conceptual design for selected alternatives was prepared. Poor soil conditions played a major role in the feasibility analysis and conceptual design for each alternative.