By Alisha A. Renfro, Ph.D., Coastal Scientist, National Wildlife Federation
The Mississippi River is one of the largest rivers in the world, carrying water, nutrients and sediment across America’s heartland, through Louisiana and into the Gulf of Mexico. The Mississippi River Hydrodynamic and Delta Management Study is a Louisiana Coastal Area project that has recently been initiated by the U.S. Army Corps of Engineers and Louisiana’s Coastal Protection and Restoration Authority. The purpose of this 5-year, large-scale study is to assess the resources of the lower Mississippi River and evaluate restoration efforts that could increase the long-term sustainability of the delta. To take serious steps toward using the river for coastal restoration, the management of the Mississippi River must be re-envisioned to regard navigation, flood protection and ecosystem restoration as equally important services provided by the river.
The hydrodynamic part of this study will focus on compiling previous scientific research and collecting new information about river discharge, water flow, changes in the river bottom and sediment availability. The information collected will be used to inform models that replicate the current conditions of the Mississippi River from the Old River Control Structure north of Baton Rouge down to the Bird’s Foot Delta. The delta management part of this study will use the newly-developed models to assess the benefits and effects of different proposed restoration projects on the river and the nearby basins.
This study is important because it provides us with an opportunity to reevaluate how we manage the Mississippi River. Currently, the river is being managed exclusively for navigation interests, which has directly contributed to Louisiana’s coastal land loss crisis over the last 80 years. However, despite this focus on navigation, increases in the cost of dredging and decreases in the Corps of Engineers’ dredging budget have threatened to diminish the depth and width of the navigation channel, reducing the cargo capacity the ships can carry and decreasing the ability of U.S.-produced exports to compete on the world market.
Integrating well-designed river diversions into the management of the river has the potential to be a win-win-win for the Mississippi River Delta: restoring the ecosystem, providing a more reliable navigation channel and bolstering the flood protection system. Sediment diversions can mimic the natural processes that once built the surrounding delta. They can also remove sediment from the river, which reduces the need and cost for dredging in the navigation channel. During flood events, river diversions can also be used as additional outlets for flood waters, reducing pressure against the flood protection levees that protect communities and important infrastructure.
The Hydrodynamic and Delta Management Study is an important tool that will improve the understanding of the current conditions of the mighty Mississippi River and the resources available for coastal restoration. It is imperative that the information from this study be used to accelerate large-scale ecosystem restoration efforts and better manage the river for the important services it provides not only to Louisiana, but to the entire nation.