Interaction of nearshore, beach and dune systems: implications for barrier island morphology (Invited)

Improvements and advances in technology permit the measurement of sediment transport and fluid dynamics at increasingly smaller temporal and spatial scales. While these studies provide greater insight about small-scale processes, it remains unclear how to transfer this improved understanding of these processes to the convergences and divergences of transport that are ultimately responsible for the evolution of nearshore, beach and dune environments. A series of field experiments are used to examine how small-scale processes and the exchange of sediment amongst the nearshore, beach and dune is dependent on the antecedent morphology. Specifically, the transport of sediment from beach to dune is shown to depend on the synchronization of sediment supply and transport potential that vary as the beach and backshore evolve. The evolution of the beach and backshore in turn depends on the transformation of the incident wave field over the nearshore profile, which is dependent on the bathymetry of the inner-shelf. In this respect, the interaction of nearshore, beach and dune systems is self-reinforcing and evidence is presented to show this interaction is responsible for the alongshore variation in barrier island morphology. It is argued that the dependency of process on morphology creates new opportunities for research in which changes in process vary with changes morphology in both space and time.