Hindcast of Hurricane Sally impacts on barrier islands in the Gulf of Mexico

We performed XBeach and ADIRC+SWAN model simulations of Hurricane Sally over Dauphin and Petit Bois Islands off the Alabama-Mississippi coast to evaluate the morphologic response. Simulated water levels compared well with NOAA tide gauge observations to the east of Dauphin Island with a high model skill of 0.9. In addition, the XBeach model results of water levels, mean current speeds and significant wave heights agreed with ADCIRC+SWAN simulations near the offshore boundary and in the channel. Qualitative comparisons between the XBeach simulations and post-storm lidar observations confirmed model predictions of overwash. However, XBeach predicted minor breaches in Dauphin Island, which were not observed. This effort is part of a larger project in which several hydrodynamic and morphodynamic models will be coupled to produce hindcasts over a 15-year period for a larger region along the coast. These evaluations will provide local managers with strategic tools to make decisions about various coastal restoration alternatives.