BEACH, DUNE AND OFFSHORE PROFILE RESPONSE TO A SEVERE STORM

Abstract: Extensive field survey data collected prior to and following the impact of Hurricane Opal in 1995 on the Panhandle Coast of Florida provides a very comprehensive database, possibly the most comprehensive ever collected, by which to document and analyze sand transport response to a severe storm event. Profile surveys obtained prior to the hurricane were compared with post-storm surveys to document beach and dune erosion and related offshore sand transport along the Florida Panhandle Coast. The most severe dune erosion occurred near and to the right-hand side of the location of the hurricane landfall. High erosion was documented across the entire Panhandle Coast for a distance of over 150 miles (241 km.). Erosion trends across an analyzed portion of the Panhandle Coast show clear correlation to beach slope and to the scale parameter, A, which corresponds to profile shape. Upland lake outlet features appear to increase storm-induced beach erosion in the vicinity of the outlets. Offshore deposition of eroded sand extended to water depths of 40 feet (12 m.) below 0.0 (NGVD). Periodic follow-up surveys over a 2 to 3 year period after Opal have shown some beach and nearshore bar recovery, but little natural dune recovery or landward redistribution of deeper-water sand accumulations deposited by Hurricane Opal