Presenter: Tarandeep Kalra (Akima Systems Engineering Contracted to the USGS Woods Hole)

Description:
The presence of vegetation results in slower flow velocity, dampened wave energy, and trapping of particulate matter in marsh and estuarine environments, thus providing a habitat for several species and acting as a natural barrier during coastal storms. Recent advances in the open source COAWST modelling framework enable the dynamic evolution of both submerged aquatic vegetation and emergent marsh vegetation by including two different modes of growth. The change in submerged aquatic vegetation (SAV) is modeled based on temperature, nutrients, and light climate in the water column. The emergent marsh vegetation is modeled through a change in biomass production resulting in organic accretion, which is determined by the hydroperiod parameters and the elevation of the marsh cells in the computational model. Both modes of vegetation growth cause an evolution of SAV and marsh vegetation properties (e.g., density, height) that influences currents and waves and in turn affects the modeled sediment transport. We present three different application examples: 1) application of SAV growth model to West Falmouth Harbor, where the controls of bathymetry and excess nutrient loading impact the coverage of modeled SAV; 2) application of marsh vegetation model to two creek systems with different tidal ranges within the Barnegat Bay estuary to show how accretion due to organic sediment affects 90% of the marsh complex area; and 3) application of both modes of vegetation growth in the region of Chesapeake Bay that covers a part of Eastern Neck National Wildlife refuge. We study both shorter time scale evolution (on the order of months) to evaluate the dynamics of SAV growth and longer time scales focused on marsh vegetation to predict if the marsh complexes in the area can keep up with relative sea level rise (RSLR).