Coastal Physical Oceanography @ Stony Brook

Observations:  Seven moorings were deployed across the channel in the region of the ETM zone from April to August 2011. Timeseries of along-channel sediment transport reveal a consistent pattern of sediment export across the entire estuary during periods of high river discharge, followed by a transition to import within the channel and export on the flanks during low river flow. Along-channel transport is driven primarily by mean advection, with tidal pumping contributing to about 30% of total transport. Tidal pumping, linked to tidal asymmetries in stratification and sediment resuspension, was shown to drive both ebb-driven export and flood-driven import depending on the tidal variability of stratification.  Across-estuary sediment is driven by the mean circulation and can rework sediment from the flanks into the channel.

Modeling: A 3-dimensional Regional Ocean Modeling System (ROMS) coupled hydrodynamic and sediment model is used to look at the spatiotemporal variability of the ETM structure.  We model 3 noncohesive sediment types: silt, fine sand, and medium sand.  The model provides  insight about the spatial variablity of the mean cross-estuary circulation, which has important impacts on lateral sediment transport  and the trapping efficiency of the ETM.