Needs in Louisiana

Ecosystem Forecasting Needs & Opportunities Abound in Coastal Louisiana

Coastal Louisiana is nestled in the Mississippi River deltaic complex, which is one of the largest deltaic systems in the world. Given the natural progradation & degradation of deltas, coastal Louisiana is in a constant state of flux. Unfortunately, human activities have expedited the rate of wetland degradation over the last century, such that the current dynamic of landscape change is a net loss of wetland area.

A notable feature of coastal Louisiana is the wide estuarine gradient ranging from inland fresh water marshes & forested wetlands to brackish & saline marshlands along the coast. Barrier islands are another important feature of the Louisiana coast, but unfortunately, these barrier systems continue to be some of the most vulnerable coastal features on the Louisiana landscape.

Ecosystem forecasting can help us understand how proposed restoration projects could potentially affect coastal salinity, landscape change (land building), habitat change, habitat use, & water quality. Likewise, the development of conceptual ecological models can help focus our knowledge of this dynamic coastal system as well as identify performance measures & critical scientific & engineering unknowns & uncertainties.

 Photo of a barrier island with terracesPhoto of salt marshPhoto of a cypress swamp 


 

Retreating Coast

What is at stake

High Rates of Wetland Loss Have Put Coastal Louisiana in a State of Peril  

Coastal Louisiana is home to the nation’s largest port complex in both tonnage and infrastructure, & produces or transports nearly one-third of the nation’s oil & gas supply. In addition, the coastal Louisiana ecosystem provides nationally-important fish & wildlife habitat that supports the nation’s second-largest commercial fishery & over $1 billion per year in recreational fishing & hunting revenues. All of these activities are supported in Louisiana because of the close proximity of its skilled workforce to the Gulf of Mexico. Coastal land loss has placed these economic & natural resources at increased risk of loss due to the intense effects of waves & storm surges from hurricanes. Restoration of the coastal ecosystem can work synergistically with levees & floodgates to provide an integrated flood protection system that allows continued resource production and sustains the ecosystem services on which the nation relies.


 

Fourchon Community

USGS land loss in coastal Louisiana


 

Coastal PlatformDying cypress forest

 

 


What processes are at work           

Degraded salt marsh near Port FourchonSubsidence, Erosion, & Hydrologic Modifications Are Primary Causes of Wetland Loss in Coastal Louisiana.

Subsidence, sediment erosion, & hydrologic modification are thought to be the primary causes of wetland area loss across coastal Louisiana. Although subsidence and erosion are naturally occurring processes known to shape landscapes around the world, it is thought that human activities in coastal Louisiana have detrimentally expedited these processes, such that a net loss of land area currently exists. Hydrologic modification resulting from human activities in the coast has lead to the increased problem of salt water intrusion.


 Large navigation channels are conduits for storm surge & salt water intrusionPipeline channel


Sediment deposition into wetlands is impeeded by the presence of leveesCommunities in coastal Louisiana are often surrounded by levees to protect from flooding 


Diagram showing benefits of intact barrier islands

Photograph of severely degraded barrier island in coastal Louisiana


 

What are the trade-offs

Many Trade-offs Must be Considered When it Comes to Restoration

Many difficult trade-offs must be addressed when considering large-scale restoration projects. Although large-scale riverine diversions have the potential to rebuild & replenish areas of historical wetland loss, they also have the capacity to substantially alter the salinity dynamics of an entire basin by reducing the average annual salinity.  A large shift in salinity results in a shift in fish & wildlife habitat, which could impact not only the commercially important species, but also the recreationally important species.  Flooding from large-scale diversions could also impact coastal communities.

Another trade-off is where to use limited sediment & freshwater resources.Trade offs associated with using riverine sediment for restorationThere are trade-offs regarding where to utilize limited sediment & freshwater resources

 

 

 

 

 

 

 

 

 


What can be done

Large-scale Coastal Restoration Programs Must Be Implemented Now

Coastal restoration programs have proposed & implemented a number of small-scale restoration projects for the last several decades. Example projects that have either been proposed or implemented include terrace building, rock shoreline stabilization, beneficial use of dredged sediment, sediment delivery via pipeline, as well as both large-scale (100,000cfs) & small-scale (500cfs) riverine diversions.

The CLEAR Program specializes in ecosystem forecasting to assess the potential effects of proposed restoration projects. The CLEAR Program has the ability to simulate 50 years of hydrodynamics, landscape change, & changes in habitat type & use across the coastal Louisiana geographic domain.

In 2004, the CLEAR group provided ecological forecasts of the potential effects of the restoration alternatives proposed by the Louisiana Coastal Area (LCA) for the Chief of Engineers report. In 2007, the Louisiana Coastal Protection & Restoration Authority (CPRA) asked the CLEAR Program to analyze suites of restoration projects as part of Louisiana's Comprehensive Master Plan for a Sustainable Coast.

Conceptual diagram of coastal LA under an aggressive restoration regime

 

 

CLEAR landscape change output map 


 

For more information on Needs in Louisiana, view these publications:

summary icon pdf icon Permanent Link Land Area Change in Coastal Louisiana: A Multidecadal Perspective (from 1956 - 2006)
summary icon pdf icon Permanent Link Land Area Change in Coastal Louisiana: A Multidecadal Perspective (from 1956 - 2006)
summary icon pdf icon Permanent Link Integrated Ecosystem Restoration & Hurricane Protection: Louisiana's Comprehensive Master Plan for a Sustainable Coast
summary icon pdf icon Permanent Link Envisioning the Future of the Gulf Coast
summary icon pdf icon Permanent Link A New Framework for Planning the Future of Coastal Louisiana after the Hurricanes of 2005
summary icon pdf icon Permanent Link Louisiana Coastal Area (LCA) Ecosystem Restoration Study
summary icon pdf icon Permanent Link Mississippi River Sediment, Nutrient & Freshwater Redistribution Study
summary icon html icon Permanent Link Scientific assessment of coastal wetland loss, restoration and management in Louisiana. Journal of Coastal Research, Special Issue No. 20.