Forecasting Storm Surge and Inundation: Model Validation

Coastal regions are increasingly vulnerable to damage from storm surge and inundation. Delft3D is used by the Naval Oceanographic Office to model the ocean dynamics in the near shore. In this study, the performance of Delft3D in predicting the surge and inundation during Hurricane Ike, which impacted the northern Gulf of Mexico in September 2008, is examined. Wave height, water level, and high-water mark comparisons with a number of observations confirm that the model does well in predicting the surge and inundation during extreme events. The impact of using forecast winds based on the best-track data as opposed to hindcast winds is also investigated, and it is found that the extent of inundation is represented reasonably well with the forecast winds. In Delft3D, waves can be coupled to the hydrodynamic component using the radiation stress gradient method or the dissipation method. Comparing the results of using the two shows that for low-resolution grids such as that needed for a forecast model the dissipation method works better at reproducing the water levels and inundation.