Predictive Models

The Predictive Models developed for the Master Plan perform two different functions. First, the models assess how the coast will change in 50 years if no further action is taken to restore Louisiana’s coastal ecosystem and reduce flooding risks. Second, the models look at detailed project information and assess how the coast will change in 50 years if certain protection and restoration projects are constructed.

The model results help us learn more about the way the coast works, and they make it easier to identify projects that deliver the most value. Most of the models can be run on a desktop computer. Others, especially the storm surge model, run more efficiently on computer clusters or on super computers.

The 2012 Coastal Master Plan must integrate both restoration and protection. This mandate defined the models we selected and how they work.

  • To reflect restoration outcomes, the models looked at how land changes throughout the coast—where land is building and where it’s disappearing. The models also evaluated ecosystem services, the benefits provided to people by Louisiana’s coast.  These range from providing the right conditions for oysters and shrimp, to ecotourism and storm surge attenuation.
  • To reflect risk reduction outcomes, we used models that evaluated storm surge and economic damage from flooding.

The Predictive Models used in the master plan are organized into seven groups, or modules. Each module represents a different aspect of how the coastal landscape changes over time.  Some of these modules include many individual models.  For example, there were 15 separate species habitat models within the Ecosystem Services group. The characteristics of each module are discussed below.

The Seven Modules

1. Eco-Hydrology
Predicts changes in water characteristics within estuaries. This group of models predicts water levels, salinity patterns, sediment delivery, and some aspects of water quality. They use output from the Wetland Morphology group to determine the shape and size of open water bodies. Output from the Eco-hydrology model group is used by the Wetland and Barrier Shoreline Morphology, Vegetation, and Ecosystem Services model groups.

2. Wetland Morphology
Predicts changes in wetland areas, taking into account the loss of existing wetlands, the creation of wetlands by both natural and mechanical processes, and the fate of those newly created wetlands. This model has been improved over past efforts to consider more factors as predictors of land change. This group of models uses salinity and water level data from the Eco-hydrology group, as well as data from the Vegetation group, and provides information on land configuration to the Storm Surge/Waves, Vegetation, and Ecosystem Services model groups. It also produces outputs that reflect the potential for carbon sequestration in coastal wetlands.
3. Barrier Shoreline Morphology
Predicts changes in the shape, location, and elevation of barrier islands and the size of tidal inlets over time, including land gains resulting from restoration activities, as well as land loss from wave erosion, sea level rise, and subsidence. It is based on understanding gained from the Barrier Island Comprehensive Monitoring (BICM) program as well as years of other research. It uses inputs from the Wetland Morphology and Ecohydrology groups to predict the volume of tidal waters moving through inlets. Data on how these inlets change in size is then fed to the Ecohydrology group. Data on land configuration is fed to the Storm Surge/ Waves model group. This is a new model created to support the Coastal Protection and Restoration Authority and the 2012 Coastal Master Plan.
4. Vegetation
Predicts the location and type of vegetation that will be found throughout the coast, including submerged aquatic vegetation. It provides information about the conditions influencing plant growth, based on newly available data from the Coastwide Reference Monitoring System- Wetlands (CRMS-Wetlands). This model receives input on landscape and water quality characteristics from the Wetland Morphology, Barrier Shoreline Morphology, and Eco-hydrology groups, respectively. The output is used by the Storm Surge/Waves and Ecosystem Services model groups. This is a new model created to support the Coastal Protection and Restoration Authority and the 2012 Coastal Master Plan.
5. Ecosystem Services
Predicts how well Louisiana’s future coast will provide habitat for commercially and recreationally important coastal species and habitats for other key services. This group of models uses inputs from all other model groups. It includes habitat suitability indices for American alligator, muskrat, river otter, spotted sea trout, brown shrimp, white shrimp, largemouth bass, gadwall, green-winged teal, mottled duck, neotropical migrants, roseate spoonbill, wild-caught crawfish, and eastern oyster. These species were selected for one or more of the following reasons: they are thriving in coastal Louisiana, they are of commercial or recreational importance, and/or their habitat would likely be either increased or decreased by restoration and protection projects. In addition to habitat models, many of which were based on existing models, new models were developed to reflect potential for storm surge/wave attenuation, nature based tourism, freshwater availability and support for agriculture/ aquaculture.
6. Storm Surge/Waves
Predicts the effects of structural protection (i.e. levees and floodgates) projects on storm surge depth and wave height from hurricanes with a range of size and intensities. This model group uses output from the Wetland and Barrier Shoreline Morphology and Vegetation groups to determine landscape characteristics and provides information on flood depths for use by the Risk Assessment group. This group also evaluates changes in flood depths. This output was used to evaluate nonstructural options and potential support for agriculture.
7. Risk Assessment
Predicts asset damage that would be caused by storm surge flooding and waves. It estimates the flooding that would result from levee overtopping and/or inundation in areas without structural protection. For enclosed structural protection systems (polders) it also factors in the possible failure of flood protection structures. This model receives input from the Storm Surge/Waves model, and its output is used to estimate the reduction in asset damages that could occur in given locations if a given structural or nonstructural project is implemented. This is a new model created to support the Coastal Protection and Restoration Authority and the 2012 Coastal Master Plan.