Integrated Modeling of Coastal Processes and Linkages to Management Applications

Science Center Objects

Coastal wetlands provide valuable ecosystem services such as wave attenuation, surge reduction, carbon sequestration, wastewater treatment, and critical habitats for endangered fish and wildlife species. However, wetland loss threatens the capacity of coastal wetlands to provide these ecosystem services.

Figure 1. Structure of the integrated spatial landscape-vegetation-elevation modeling system

Figure 1. Structure of the integrated spatial landscape-vegetation-elevation modeling system

Science Issue and Relevance: Coastal wetlands provide valuable ecosystem services such as wave attenuation, surge reduction, carbon sequestration, wastewater treatment, and critical habitats for endangered fish and wildlife species. However, wetland loss threatens the capacity of coastal wetlands to provide these ecosystem services. The contributing factors to wetland loss include natural disturbances (e.g., hurricanes, sea-level rise [SLR] and climate change) and anthropogenic influences (e.g., land-use change and reduced sediment supply due to construction of levees and dams). Coastal ecosystem restoration and protection efforts strive to maintain or enhance the ecosystem services provided by coastal wetlands. The fundamental work in restoration and protection is to maintain wetland area and sediment surface elevation to keep pace with SLR and changing hydrological conditions. As such, a wetland morphology model is needed for resource managers to assess and project wetland area and elevation change under natural and anthropogenic impacts.

Figure 2. Current and proposed MR diversions in Louisiana deltaic wetlands. (Source: LaCPRA)

Figure 2. Current and proposed MR diversions in Louisiana deltaic wetlands. (Source: LaCPRA)

Methodology for Addressing the Issue: USGS scientists and collaborators will develop a spatial coastal wetland morphology model (Figure 1). We will use data on plant productivity and soil organic matter decomposition across coastal Louisiana from past and ongoing field studies. The soil cohort-based morphology model will incorporate non-linear feedback relationships that govern wetland elevation and landscape dynamics. The wetland morphology model will consist of primary productivity, relative elevation, habitat switch, and sediment/soil sub-models. Once calibrated and validated against field observations, the spatial morphology model will be used to examine the impacts of MR freshwater and sediment diversions (Figure 2) and sea-level rise (SLR) on wetland surface elevation and habitats types.

Future Steps: The process-based spatial wetland morphology model will be coupled with wetland soil biogeochemistry data to examine wetland carbon budgets and greenhouse gas (GHG) emissions in support of a national wetland carbon assessment.

Location of Study: 29°42’27.30’’N, 90°24’41.27’’W