Development and validation of a coastal surge and inundation prediction system

The development and validation of a coastal storm surge and inundation prediction system for operational use by the United States Navy is detailed. The system consists of the Delft3D-FLOW hydrodynamic model coupled with the Delft3D-WAVE wave model and a graphical user interface, the Delft Dashboard. The coupled system is used to model storm surge and inundation produced by Hurricane Ike along the Gulf of Mexico coast in September 2008. The hydrodynamic model is run in 2D depth averaged mode to develop a “best” simulation. The best simulation is developed after hundreds of test runs and it consists of a blended elevation dataset for use as the model bathymetry and topography, a spatially varying Manning´s N coefficient, multiple nests, atmospheric forcing from re-analysis wind and pressure fields with directional land masking, an initial water level of 0.11 m, an updated air - sea drag coefficient, and dynamically coupled flow and wave fields. The simulation results compare very favorably with observed water level. To assess the system in an operational forecast environment, the system´s sensitivity to the elevation dataset, bottom roughness, domain resolution, atmospheric forcing, drag coefficient, initial water level, and wave coupling was investigated and found to vary widely depending on the component.