By Alisha Renfro, staff scientist, National Wildlife Federation
The high rate of land loss in coastal Louisiana requires restoration efforts of the same large scale. To formulate Louisiana's 2012 Coastal Master Plan, researchers and coastal managers used a series of models to examine the ability to build and sustain land using both mechanical and natural methods that use the power of the river. Included in the analysis were eight channel realignment projects that would reroute the Mississippi River's flow through channels upstream of the present day Bird's Foot Delta south of Venice, La. Exploring the possibility of channel realignment helps coastal planners look outside the box and possibly redefine the meaning of what is possible for the futures of coastal restoration.
Among the top 25 land-building restoration projects identified in the master plan, six were channel realignment projects (2012 SMP pages SE-49 to SE-56). While none of the specific realignment projects analyzed were included in the final plan, the plan does devote resources to planning, design and engineering to help explore channel realignment locations and water discharge regimes.
While the idea of realigning the Mississippi River may seem like a novel concept, the 2012 Coastal Master Plan is definitely not the first plan to consider this path. A variety of reports, forums and workshops have suggested and discussed using channel realignment as a restoration tool. In fact, the Mississippi River system we know today is a product of the Mississippi River and Tributaries project (MR&T), which channelized and realigned the river for flood control and improved navigation.
In the past, these modifications to the Mississippi River basin served their purposes well, but the extensive levee system also severed the connection between the river and the delta it once built, thus contributing to the more than 1888 square miles of land lost in Louisiana since 1932. Today, maintaining the navigability of the lower river has become increasingly difficult as dredging budgets are reduced while the cost of dredging continues to climb. Additionally, ongoing enlargement of the Panama Canal will increase the demand for deeper draft vessels, which cannot be accommodated under current conditions of the lower Mississippi[pi River.
The status quo of the Mississippi River system and its current management is unsustainable. To build a more sustainable river system, flood protection, navigation and restoration must be considered equally important uses of the river. Restoration features, such as diversions, can serve multiple purposes: reconnecting the river with the surrounding wetlands, preferentially removing sediment from the river and providing additional flood outlets during high flow events.
To re-imagine what is possible for the lower Mississippi River Delta, the Mississippi River Delta Restoration Campaign and Environmental Defense Fund have begun developing the Lower Mississippi River Delta Design Initiative (LMRDDI). The design initiative will challenge engineers and scientists throughout the world to design new options for managing the hydraulics of the lowermost Mississippi River, downstream of New Orleans, to divert as much of the sediment, sand and mud (silt and clay) from the river into adjacent wetlands while also creating a more reliable and potentially deeper-draft navigation channel entrance.
At the heart of such designs will be the opportunity to take greater advantage of the natural processes and trends that are currently affecting the Bird's Foot Delta at the end of the river. An equally important objective of the LMRDDI is to initiate a transparent assessment of the social and ecological costs and benefits of any options for a redesigned river mouth that are developed. The "design competition" is expected to be initiated in early 2013 and will take about 18 months from beginning to end.
Large-scale problems require large-scale solutions, and those who developed Louisiana's 2012 Coastal Master Plan know this. To achieve restoration on the scale necessary to revitalize the Mississippi River Delta and slow the rate of coastal land loss, big ideas need to be cultivated. Realigning the river, large-scale diversions and the Lower Mississippi River Delta Design Initiative are just a few of the big ideas out there fore restoration. The more we can re-imagine and redefine what is possible for the region, the more hope we have for saving America's Delta.