Predictive models form scientific backbone of Louisiana Coastal Master Plan
By Alisha A. Renfro, Ph.D., National Wildlife Federation
Louisiana’s Draft 2012 Coastal Master Plan is a bold, ecosystem-scale restoration strategy that outlines a 50-year plan to combat the land loss epidemic in the Mississippi River Delta. The plan puts forth solutions to addressing the destructive impacts of sea-level rise, subsidence, increased storm intensity, marsh collapse and other factors on Louisiana’s disappearing coastline. The plan is a science-based approach that, at its core, uses a suite of linked models to predict the future of Louisiana’s coastal landscape and the potential damage to communities over the next 50 years, both with and without implementation of the plan’s restoration and risk reduction projects.
The Louisiana Coastal Protection and Restoration Authority is hosting a series of seminars at universities throughout the state to give residents an overview of the plan’s predictive modeling efforts. These seminars go hand-in-hand with the master plan public meetings held in January. At each seminar, one or two of the individual models is explained by a leading researcher in his/her related fields. A full list of seminars is available online.
This pioneering modeling effort began 18 months ago, when a group of scientists and engineers were gathered to carry out and serve as a technical advisory team for the effort. The challenge was to use existing models, or create new models if none existed, to better replicate complex coastal processes and allow for the analysis of various future environmental condition scenarios as well as over 400 different restoration and protection projects.
Seven calibrated and interconnected models — each developed and refined by a team of scientists — were used to characterize different aspects and functions of the coastal Louisiana landscape:
- Eco-Hydrology: Predicts changes in the flow of water, salinity, water level, sediment, nutrients and other aspects of water quality within the estuaries.
- Wetland Morphology: Predicts losses and changes to wetlands by analyzing factors that affect wetland elevation (e.g., subsidence, sea-level rise) and factors that affect the configuration of the landscape (e.g., storms/hurricanes, saltwater intrusion, sediment transport).
- Barrier Shoreline Morphology: Predicts changes in the barrier island shorelines and inlets due to processes such as relative sea-level rise, subsidence, erosion, storms and loss of interior wetlands.
- Vegetation: Predicts changes in the types and location of vegetation based on changes in wetland area and the movement and characteristics of water in the estuaries.
- Ecosystem Services: A group of models that predicts changes in habitat for commercially and recreationally important species as well as other key services. The individual species models included those for brown shrimp, white shrimp, American alligator, green-winged teal, eastern oyster, rosette spoonbill and others.
- Storm/Surge Waves: Predicts the storm surge and waves that result from various hurricane-level wind speeds and directions. This model is important for understanding the effect that structural protection such as levees and floodgates could have on reducing the effects of storms and waves on coastal communities, infrastructure and ecosystems.
- Risk Assessment: Predicts the damage to assets in the coastal area caused by waves and storm surge by estimating the flooding that would result from levees being overtopped and flooding in areas without structural protection.
The purpose of the 2012 Coastal Master Plan is to identify restoration and protection projects that will create a more resilient and sustainable Louisiana coastline. The suite of predictive models developed for the plan was used to predict the future of Louisiana landscape without any action, as well as the future of the coast with individual restoration and protection projects under different environmental scenarios. The glimpse into our possible future if no large-scale restoration projects are implemented is bleak, with a potential loss of 800 to 1800 square miles of land. To avoid this future, large-scale coastal restoration projects, like diversions, are required to maximize natural land-building processes and build a more sustainable future in the face of uncertain environmental conditions.