Insights into Barrier Island Evolution: Past, Present, and Future

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... [ view full abstract ]

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 variations in barrier island framework geology at Padre Island, Texas influence island formation and evolution, and explores emerging approaches to explore coastal evolution. Wavelet analysis and bicoherence models demonstrate that variations in the framework geology are spatially coincident with variations in beach-dune morphology. Forecast models were adapted to demonstrate that alongshore variations in the framework geology affect beach-dune morphology, and this influence can be directional. 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 acted as sediment sinks during island development by trapping sediment moving south while filling in the channel as an alongshore spit. Understanding the how far alongshore a paleo-channel can influence the modern beach and dune morphology is important for accurately predicting future changes to barrier island geomorphology and protecting coastal communities. Ongoing work evaluating the impact of Hurricane Harvey suggests that anthropogenic influences may represent a significant factor in future island evolution.