We will develop a process-driven spatial coastal wetland morphology model based on the spatial version of the soil cohort model for relative elevation change from Kairis and Rybzcyk (2010) and the habitat switch protocol of Couvillion and Beck (2013). The model will be driven by salinity, water level, nutrient, and sediment loading from the hydrodynamic, water quality, and sediment transport models, and by vegetation primary productivity and organic matter decomposition data from the field investigations. We will use data on plant productivity, soil organic matter decomposition, hydrology, soil properties, sediment accretion, and elevation change in Terrebonne, Barataria, and Breton Sound basins in the Mississippi River Delta Plain (MRDP) from past and ongoing field studies to calibrate and validate the wetland morphology model. Then, the spatial morphology model will be used to examine the impacts of Mississippi River freshwater and sediment diversions and sea-level rise on wetland surface elevation and habitats.
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 in providing these ecosystem services. The contributing factors to wetland loss include natural disturbances (e.g., hurricanes, sea-level rise and climate change) and anthropogenic interferences (such as land use change and reduced sediment supply due to constructions 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 surface elevation to keep pace with sea-level rise and change in 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.
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. The primary productivity sub-model will simulate emergent vegetation productivity as a function of vegetation type and limiting factors (i.e., salinity, inundation, and nutrients). The relative elevation sub-model will quantify vertical accretion from mineral sediment and organic matter, eustatic sea-level rise, and subsidence. The habitat switch sub-model will track