DEVELOPING A MULTIDISCIPLINARY UNDERSTANDING OF BARRIER ISLAND EVOLUTION

Rising sea levels and storms pose a significant threat to coastal communities worldwide and are likely to alter barrier island morphology substantially. Current models of barrier island geomorphology account for variations in storm run-up, vegetation, and pre-existing beach and dune morphology, but do not include a quantitative understanding of how variations in framework geology influence barrier island evolution. This paper presents new information about how alongshore variations in barrier island framework geology asymmetrically influence island evolution. Economic forecast models were adapted for geomorphic analysis of alongshore variations in barrier island framework geology and beach and dune morphology. Results demonstrate that alongshore variations in the barrier island framework geology exert a directional dependence on beach and dune morphology, which persist through time. Beach and dune morphology is less developed immediately south of a channel and geomorphic development increases to the south, consistent with the dominant paleo-current direction. A series of incised channels in the framework geology at Padre Island National Seashore, Texas likely acted as sediment sinks during island development by trapping sediment moving south while filling in the channel as an alongshore spit. Spit development would have continued until the channel was completely filled in. Understanding the how far alongshore a pre-existing channel can influence the modern beach and dune morphology is important for accurately predicting future changes to barrier island geomorphology and protecting coastal communities.