Storm Surge Modeling

Storm surge modeling simulates the abnormal rise of coastal water driven by a storm — principally the wind stress and low atmospheric pressure of a hurricane or extratropical cyclone — by solving the depth-integrated shallow-water equations of coastal hydrodynamics. The surge is the difference between the storm-driven water level and the normal astronomical tide, and it is the deadliest hazard of most landfalling hurricanes, capable of flooding low-lying coasts kilometers inland. The operational tradition began with Jelesnianski and colleagues' SLOSH model, documented in the 1992 NOAA technical report, which the National Weather Service still uses for real-time forecasting and evacuation planning. High-resolution research and design work increasingly uses the unstructured-grid ADCIRC model, whose application to southern Louisiana by Westerink, Luettich, and colleagues in 2008 set the standard for basin-to-channel-scale surge simulation. The defining challenges are representing the hurricane wind field accurately and resolving the complex coastal geometry — channels, marshes, and levees — that steers the water. The output is a time-evolving map of water level and overland inundation.