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Woods Hole Coastal and Marine Science Center

Woods Hole Coastal and Marine Science Center > Coastal Model Applications and Field Measurements > Research Activities > Hydrodynamic and sediment transport modeling

Coastal Model Applications and Field Measurements

Hydrodynamic and sediment transport modeling of Barnegat Bay, New Jersey

Estuarine flushing and residence time are primary physical controls on eutrophication and water quality. Barnegat Bay-Little Egg Harbor (BB-LEH), New Jersey, is a 280 km2 lagoonal back-barrier estuary connected to the ocean via 3 inlets that is subject to anthropogenic pressures including nutrient loading, eutrophication, and subsequent declines in water quality. A combination of hydrodynamic and particle tracking modeling was used to identify the mechanisms controlling flushing, residence time, and spatial variability of particle retention. The models demonstrated a pronounced northward subtidal flow from Little Egg Inlet in the south to Pt. Pleasant Canal in the north due to frictional effects in the inlets, leading to better flushing of the southern half of the estuary and increased particle retention in the northern half of the estuary. Mean residence time for BB-LEH was 13 days (d) but spatial variability was between ~0 to 30 days depending on initial particle location. Mean residence time with tidal forcing alone was 24 days (spatial variability between ~0 – 50 d); the tides were relatively inefficient in flushing the northern end of the Bay. Scenarios with successive exclusion of physical processes from the models revealed that meteorological and remote offshore forcing were stronger drivers of exchange than riverine inflow. This work demonstrates that investigations of water quality and eutrophication should take into account spatial variability in hydrodynamics and residence time in order to better quantify the roles of nutrient loading, production, and flushing.

Map of Barnegat Bay with flow arrows

Map of Barnegat Bay showing modeled residual circulation patterns in that partially explain the long residence time and poorer water quality in the northern portion of the Bay.

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