A QUANTITATIVE METHOD FOR RANKING THE GEOMORPHIC CONTROLS ON STORM SURGE PENETRATION ALONG THE MISSISSIPPI COAST DURING HURRICANE KATRINA

Coastal hazard mapping has historically been based primarily on simple models of storm inundation (SLOSH model), erosion rates, or estimated setbacks from a control line. There is still only a rudimentary understanding of how the numerous geomorphic attributes of a particular stretch of shoreline control cross-shore storm energy. An analysis of the impacts of Hurricane Katrina along the Mississippi coast provides an important addition to that understanding—a ranking of the geomorphic controls on storm surge penetration (and thus property damage). These data augment the science of coastal storm processes while providing critically important guidance for future coastal management. Previous studies of geomorphic controls on storm damage in Florida and South Carolina indicate that along those coasts, site elevation provided the best protection against property damage, followed by dune height (in front of the site) and beach width. Each site is different and different factors may exert more control along the Mississippi coast. Ultimately, the new information can be used to produce a series of coastal hazard maps that can be easily accessed via the internet by both public and private entities interested in learning about and managing their coastal hazards.

A regression analysis was used to determine which pre-storm coastal attributes influenced the observed post-storm storm-surge penetration and damage. Hurricane Katrina impacted a great length of the Gulf of Mexico Shoreline, and her effects were felt far inland. Preliminary results from Katrina have produced the following ranking: site elevation provided the best protection followed by dune height (in front of the site) and beach width. An on-going study of the impact of Hurricane Georges (1998) in Puerto Rico is exploring how consistent the results will be for a completely different geological setting. Having a quantitative understanding of coastal hazard risk is critical for producing accurate risk maps, as well as, for prioritizing spending on mitigation.