Morphologic and sedimentological signatures resulting from Hurricane Ian, southwest Florida, USA: Insight into intra-storm bidirectional sediment transport processes

The extreme conditions associated with Hurricane Ian, a large Category 4 hurricane, led to unprecedented damage to the barrier islands of southwest Florida. This study investigates the morphologic changes and sedimentological signatures of deposits resulting from Hurricane Ian along both developed and undeveloped barrier islands through a combination of sediment cores and pre- and post-storm digital elevation models. Laterally extensive washover deposits, measured up to 74 cm thick, were formed during the intensification phase of the storm surge and were primarily controlled by the degree of development and vegetation density along barrier-island interiors. Storm deposit sedimentology was influenced by the degree of development and position relative to the dune crest, with a large inclusion of anthropogenic debris along developed barrier-island interiors. During the subsiding phase of the storm surge, short, straight channels and longer, dendritic ebb-scour channels, measuring up to 2.4 m in depth, were cut into newly formed storm deposits and antecedent washover deposits from previous storms, reflecting time-dependent bidirectional sediment transport processes during Hurricane Ian. The results of this study demonstrate how bidirectional processes throughout a single large storm event have significant implications for the preservation potential of new and existing washover deposits, presenting a potential setback for long-term barrier-island migration.