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.
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.
What processes are at work
Subsidence, 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.
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.
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.
For more information on Needs in Louisiana, view these publications:Land Area Change in Coastal Louisiana: A Multidecadal Perspective (from 1956 - 2006)
Land Area Change in Coastal Louisiana: A Multidecadal Perspective (from 1956 - 2006)
Integrated Ecosystem Restoration & Hurricane Protection: Louisiana's Comprehensive Master Plan for a Sustainable Coast
Envisioning the Future of the Gulf Coast
A New Framework for Planning the Future of Coastal Louisiana after the Hurricanes of 2005
Louisiana Coastal Area (LCA) Ecosystem Restoration Study
Mississippi River Sediment, Nutrient & Freshwater Redistribution Study
Scientific assessment of coastal wetland loss, restoration and management in Louisiana. Journal of Coastal Research, Special Issue No. 20.