Model Domain and Gridding

The model domain stretches from Rockway Inlet to the west, eastward some 75km to the Quantuck Canal between Moriches and Shinnecock Bays. While the central portion of Great South Bay is the central focus of the study, the inlets to the east and west have a large effect on the exchange properties of the region which meant that we had to cover the entire area. The figures below, from Goggle maps, show the area. Note that the western end of Great South Bay is very complicated with many mud flats and narrow chanels which dictated the high spatial resolution needed to adeqautely simulate the flow through the area.

Initially, we had intended to extend the grid offshore only onto the continental shelf in small regions surrounding each of the four inlets. After a number of test runs we realized that the tidal phasing between the inlets could have a significant effect on the residual flow within the Bay and was not easily parameterized. As a result, the grid was extended offshore to approximately the edge of the continental shelf and east and west from Sandy Hook almost to Montauk Point. The figure to the right shows the bathymetry over the extent of the model domain.  Tidal boundary conditions along the outer boundary and in the entrance to New York Harbor were determined from a larger-scale run of the barotropic ADCIRC model for the entire New York Bight.

The gridding for the model was based upon the USGS HHW coastline using the SMS gridding routine.  Because of the channelized western end of the Bay, extensive and iterative hand-editing of the grid in that area was required.  In the end, a total of 59531 nodes and 114637 triagular elements were needed to represent the present-day conditions.  Model bathymetry was interpolated onto the grid from a combination of NOS survey data and modern multi-beam data collected by Roger Flood in the central and eastern Great South Bay since 2001 while USGS seamless topography data was used to define the marsh elevations in the western reaches of the domain.

The final model bathymetry for the Great South and Moriches Bays for the current conditions/base-case runs is shown to the left while an annotated bathymetric map to the right shows the locations of  points interest discussed in the text.