Forecasting Storm Surge, Inundation, and 3D Circulation along the Florida Coast

An integrated storm surge modeling system, CH3D-SSMS, based on the CH3D (Curvilinear-grid Hydrodynamics in 3D), has been further enhanced to enable simulation of storm surge, wave, inundation, and 3D circulation along Florida coasts during recent tropical cyclones. Until recently, CH3D was coupled to a barotropic basin-scale model to simulate 2D/3D barotropic response of coastal and estuarine waters to tropical cyclones. In this study, CH3D is coupled to a 3D baroclinic circulation model HYCOM which covers the North Atlantic and Gulf of Mexico to enable simulation of salinity, temperature, and currents in addition to water level in coastal waters. Tidal open boundary condition is obtained from ADCIRC. The CH3D is also coupled to a coastal wave model SWAN which receives open boundary condition from the basin-scale WAVEWATCH-III model. The 3D baroclinic CH3D-SSMS is used to simulate the surge, inundation, and salinity in the NE Florida coast, including St. Johns River and Guana-Tolomato-Matanzas National Estuarine Research Reserve (GTM-NERR) near St. Augustine, during Tropical Storm Fay in 2008. The slow moving storm with heavy precipitation caused significant inundation in St. Johns River while lowering salinity inside the GTM-NERR. While the water level during Fay was accurately simulated, accurate salinity simulation required the use of precipitation forecasts from HYCOM and river flow forecasts from NWS' AHPS. Inadequate river flow forecast results in salinity simulation errors.