Environmental Engineering Recommendations for Restoring Land in Louisiana’s Delta Region

Since the 1930s, the Louisiana has lost coastal land mass that is the equivalent of the state of Delaware. A scientific working group has developed recommendations for a plan to divert sediment from the Mississippi River to allow for restoration of land in the Louisiana delta.      

Map depicting land loss in Louisiana’s Mississippi delta region.

Prior to the 1930s, people who lived along the Mississippi River endured catastrophic floods that destroyed homes, crops, and even towns. In order to provide relief these communities, the Army Corp of Engineers built a series of levees that diverted the water flow along the Mississippi River not only to reduce the risk of flooding but also to facilitate navigation for commercial vessels. While the levee system accomplished these goals, changing the river flow had an unintended consequence –  the diversion starved the coastal land areas of more than 70 percent of the sediment needed to replace that lost due to erosion and storm surges. Compounding these issues are upstream dams, sea level rise, subsidence, catastrophic hurricanes, including Katrina and Rita, as well as the construction infrastructure for the oil and gas industries and the BP oil spill. Consequently, during the past 80 years, land surveys show Louisiana has lost 1,900 square miles of land at a rate equivalent to one football field worth of land per hour.

The USGS video below reviews the land loss that has occurred along the Louisiana coast.

Without intervention, Louisiana’s land loss will not only continue, but accelerate due to the anticipated increases in the rate of sea level rise and subsidence. Additionally, the Gulf of Mexico has been relatively quiet during the past decade in terms of tropical storms. This lull is not expected to last much longer, which will lead to land loss due to the extreme wave action and severe storm surges associated with hurricanes.  What is the importance of the Louisiana coastal region? What can be done to restore and rehabilitate the land in Louisiana’s Mississippi delta region?

The Rationale for Restoring Land Along the Louisiana Coast

The Atchafalaya Basin, located in Louisiana’s delta region, is rich with bald cypress and wildlife.

Today, two million people call Louisiana’s coastal region home. These communities contribute tens of billions of dollars to the United States’ economy through their fisheries, trade routes, and energy industries. The region’s forests, swamps, wetlands, and coastal waters are habitats for numerous endangered mammals, reptiles, and waterfowl, as well as fisheries that provide livelihoods for those working in the seafood industries. Clearly, further land degradation along the Louisiana coast would cause significant economic harm to the state and national economies.

Sediment Diversion Integral to Restoring Land Along Louisiana’s Coast

Project Funding

While the 2010 Deepwater Horizon oil disaster in the Gulf of Mexico caused immense damage to Louisiana’s coastal areas, Congress passed the 2012 RESTORE Act that mandated 80 percent of the money collected from the penalties levied against BP and other responsible parties was to be put into a trust fund. The legislation allows Louisiana, along with the four other Gulf Coast states, to pull money from the trust to pay for coastal restoration and remediation projects. The Louisiana legislature tasked the Coastal Protection and Restoration Authority  (CPRA) to administer the state’s share of these funds, as well as payments made directly by BP, and to manage coastal restoration and rehabilitation projects.

2012 Coastal Master Plan

In 2012, the CPRA published and implemented Louisiana’s first Comprehensive Coastal Master Plan.   The goals of the plan included sustaining coastal ecosystems, protect the communities along the Louisiana coast, and preserving the region’s economic and cultural resources. The areas addressed in the 2012 Coastal Master Plan are as follows:

• Transportation and navigation along Louisiana’s coastal waterways
• Port-related projects
• Development of the oil and gas industries along the coast
• Land use
• Management of groundwater resources

Since the current plan expires next year, the process of updating and adding new projects to the 2017 Coastal Management Plan is underway. The new plan current has 52 projects.

Sediment Diversion Included in the 2017 Coastal Management Plan

As part of the planning process for the 2017 Coastal Management Plan, an elite group of coastal scientists and community stakeholders formed the Sediment Diversion Operations Expert Working Group. The purposes of this group are to identify best practices for diverting sediment from the Mississippi River in order to restore the land along the Louisiana coast, as well as to ensure minimal disruption to the people, industries, environment, and wildlife in the deltas. The diversion system designed by the working group will be built into the levee systems to allow water, sediment, and vital nutrients to flow into the coastal wetland areas.

As part of the final Sediment Diversion Operations report, the working group made the following key recommendations:

• The flow of the diverted sediment and water needs to mimic the natural flood cycles of the Mississippi River. The peak flooding periods start during November and end in the late springtime.
• The diversion systems need careful monitoring and the operations need to be flexible in order to account for severe weather events, such as hurricanes.
• The diversion needs to start gradually during the first five to ten years to allow for the formation of distribution channels, to decrease the risk of flooding, and to allow the coastal flora and fauna to adapt to the changes.
• Develop and implement an extensive public information program about the sediment diversion project. Solicit public input before and during the project to devise any mitigation of undesired socioeconomic effects related to the project.
• Oversite of the project should be handled via a transparent and accountable governance structure.

The video below provides an in-depth discussion of the coastal land restoration projects, including the use of sediment diversion methods.

What is your opinion about this project? What do you think about the recommendations of the working group?