SEDIMENT REDISTRIBUTION PATTERNS AND SUBAERIAL VOLUME CHANGES INDUCED BY HURRICANE IVAN: GULF ISLANDS NATIONAL SEASHORE, FLORIDA
Inundation and overwash regime impacts at GINS yielded an average reduction in foredune elevations on the order of 1.6 m. At Ft. Pickens, along the west end of GINS, few features with pre-storm elevations above 1.5 m (NAVD) remained. The interior platform was reduced to a uniform elevation of about 1-m (NAVD), and locally, cross-shore transport resulted in 50 to 120 m of landward migration of the back-bay shoreline. However, post-storm sediment volumes indicate an overall net loss, indicating some offshore transported occurred, likely during the early building phases of the storm. Further east, higher initial foredune elevations in conjunction with greater cross-shore and long-shore continuity factors yielded a more heterogeneous morphologic response, and reduced overall net sediment losses. Barrier response to this severe storm was largely controlled by the magnitude of storm forcing, in conjunction with antecedent morphological factors. These insights can aid park managers in assessing existing resource vulnerabilities, and mitigating future storm impacts.