Coupled Circulation, Wave, and Morphology-Change Modeling, Shinnecock Inlet, New York

Analysis of five high-resolution bathymetric data sets collected at Shinnecock Inlet, NY indicates the evolution of ebb shoal morphology between 1994 and 2000 was primarily controlled by migration of the main navigation channel. Increased wave activity during the 1997 El Nino accelerated the rate at which the channel was deflected toward the west. These bathymetric data are applied in this study for assessment of morphology change calculation conducted within the Inlet Modeling System developed by the U.S. Army Corps of Engineers Coastal Inlets Research Program. Circulation, sediment transport, and morphology change were calculated by the two-dimensional finite-difference model M2D, which was coupled with STWave for computation of wave-driven currents. A simulation was conducted for August to November 1997 in which waves from NDBC Station 44025 were input as forcing for STWave. Tidal forcing for M2D was prescribed with water levels extracted from a regional ADCIRC model. Major observed changes in inlet morphology were reproduced by the modeling system. These changes are: scour and westward migration of the navigation channel, accretion along the eastern flank of the ebb shoal, and accretion of the seaward extent of the ebb shoal.