2019 CSDMS meeting-093


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Impact of Submerged Aquatic Vegetation on Water Quality in Cache Slough Complex, Sacramento-San Joaquin Delta: A Numerical Modeling Study

Nicole Cai, Virginia Institute of Marine Science Gloucester Point Virginia, United States. ncai@vims.edu

A new submerged aquatic vegetation (SAV) model is developed and incorporated into the fully coupled hydrodynamic-water quality framework of SCHISM-ICM in order to account for the impacts of SAV to the aquatic system. This multidisciplinary study incorporates biogeochemistry, hydrodynamics, numerical computing and field survey data. The interactions between SAV, hydrodynamics and biogeochemistry contain several complex nonlinear feedback loops, which had not previously been explored. My research uses a fully coupled hydrodynamic-biogeochemistry-SAV model to quantitatively explore the relative contributions of each process associated with SAV (from purely physical processes such as dragging, to purely biological processes such as growth) to its total impact on the system. Through applications, we find that SAV generally encourages phytoplankton accumulation by increasing the residence time, while suppressing local primary production of the phytoplankton through competition for light and nutrients. The dynamic feedback of SAV to hydrodynamics is significant, accounting for up to 80% of the changes of the water quality variables. Our results highlight the importance of incorporating the nonlinear feedback loops in a model in order to correctly account for complex hydrodynamic and biogeochemical processes. This new SAV model has immediate applications in the monitoring and guidance of SAV removal (e.g. San Francisco Bay and Delta) or recovery (e.g. Chesapeake Bay) in different systems over the world.