EFFECT OF DEM ACCURACY ON HURRICANE SURGE MODELING

Hurricane storm surge models are an essential tool in pre-disaster hurricane mitigation for determining the potential impact of a storm prior to landfall. They are the first step in creating mitigation strategies for limiting losses to property and life in the affected region. Surge models range from simple bathtub models to the more complex NOAA Slosh Model. Standard models in use, including SLOSH, SURGE, and HazusMH, all use readily available USGS DEMs as the basis for topographic calculations in determining the flood extent of the storm surge. This study investigates the changes in the predicted flood extents and footprints given by the models when using DEMs of increasing accuracy. SLOSH model runs have been made for Charleston, SC, using four different resolution DEMs as controls. The first is a standard 1:24,000 USGS DEM (10-meter grid based on 30-meter sampling). The second is an enhanced USGS true 1:24,000 DEM developed for the region by the USGS (true 10-meter DEM). The final two are enhanced versions of the second USGS data set augmented by LIDAR data. The LIDAR-enhanced DEMs are built using a 5-meter grid cell. The first is simply a ground elevation model while the second includes the building footprints, story, and height information to determine the impact of the storm surge on and around existing buildings. This study will help emergency managers to understand the types of data that they need to collect and the true sensitivities and limitations of the models they use to make decisions.