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Modeling hydrodynamics, water quality, and benthic processes to predict ecological effects in Narragansett Bay
Citation:
Abdelrhman, M. Modeling hydrodynamics, water quality, and benthic processes to predict ecological effects in Narragansett Bay. Coastal and Estuarine Research Federation (CERF) 23rd Biennial Conference, Portland, OR, November 08 - 12, 2015.
Impact/Purpose:
The presented three dimensional model for Narragansett Bay is calibrated and can be used to predict hydrodynamics and water quality as well as benthic sediment processes and hypoxia in the Bay. The model can be used as a tool to guide decisions related to the anticipated future changes in nutrient and contaminant loads as well as some effects related to climate change.
Description:
The environmental fluid dynamics code (EFDC) was used to study the three dimensional (3D) circulation, water quality, and ecology in Narragansett Bay, RI. Predictions of the Bay hydrodynamics included the behavior of the water surface elevation, currents, salinity, and temperature in 3D during the full year of 2009. Water quality predictions covered 21 state variables in the water column and 27 state variables in the benthic sediment. The water quality in the water column and in the benthic sediment were fully coupled with the depositional flux of particulate organic matter from the water column to the sediment and the upward flux of the remineralized nutrients from the sediment back to the water column. All benthic fluxes were calibrated to existing regressions of observations from the Bay. Model performance for hydrodynamics and transport was evaluated with a matrix of nine skill parameters to compare predictions to observations at twelve buoy stations. Seasonal hypoxia in the water column was studied by modeling dissolved oxygen concentration together with three species of phytoplankton (cyanobacteria, green algae, and diatoms). Periods of low oxygen concentrations in bottom waters were identified for acute and chronic levels that can affect pelagic and benthic biota. Scenarios for various mitigation measures were examined including reduction of nutrient loads from waste water treatment plants.