Changing Course - The Moffatt & Nichol Team Solution- A “Systems Approach” to a consolidated and sustainable Lower Mississippi River Delta.

Jonathan Paul Hird1, Robert Twilley2, Jeff Shelden1, Jeff Carney3, Ioannis Y Georgiou4 and Claire Agre5, (1)Moffatt & Nichol, (2)Louisiana State University, College of the Coast and Environment, Baton Rouge, LA, United States, (3)Louisiana State University, Coastal Sustainability Studio, Baton Rouge, LA, United States, (4)University of New Orleans, Department of Earth and Environmental Sciences, New Orleans, LA, United States, (5)West8, New York, NY, United States
Abstract:
In response to the Changing Course Design Competition a bold, innovative “systems approach” to link the specific needs of the region’s ecosystem, economy and community is proposed. “The Giving Delta” plan empowers the Mississippi River’s seasonal natural flood pulse to maximized sediment capture in order to build and maintain wetlands, mitigate the effects of climate change and subsidence, and to slow the inevitable marine transgression of the Delta. Sediment capture is optimized by a series of sediment retention strategies and passive sediment diversion structures, as well as establishing a new deep draft navigation channel connected to the Barataria Bay shoreline littoral zone 40 miles north of the current channel.

This paradigm shift from “flood control” to “controlled floods”, connects the River’s natural flood pulse to the coastal landscape. Using hydraulic residence time in the basin as a design and operational criteria for these controlled and passive structures, balances estuarine recovery and system response tolerance in order to determine the magnitude of the peak flows possible without intolerable salinity suppression in the receiving basins. Seasonal salinity gradients can be established that enable the diversion program to operate in harmony with and promote regional fisheries. On an annual basis, fisheries, communities and ecosystems will adapt to seasonally changing conditions.

This plan is not designed to completely rebuild the wetlands that have been lost over the last century. Instead, the design encourages wetland adaptation to accelerated sea level rise in the coastal basins. With this plan, the basin ecologies would “self-organize” in parallel to the human settlement’s natural ability to adapt and change to this long-term vision, as a new, consolidated and sustainable Delta emerges. By establishing a framework of implementation over 100 years, incremental adaptation minimizes individual uncertainty and costs within each human generation.

Back to: Moving the Mississippi River Delta toward Long-Term Sustainability: Opportunities and Limitations I