Sediment transport on dissipative, intermediate and reflective beaches

In this paper, we review and synthesize field measurements of suspended sediment transport on the shoreface of dissipative, intermediate and reflective beach states. The morphodynamic beach state continuum was originally established in the 1970s but at the time, only hydrodynamic processes and morphologies in these various states were described. Since the early 1980s when sensors capable of resolving suspended sediment concentration at intra-wave time scale became available, many studies have examined suspended sediment transport by waves and currents on the shoreface. The synthesis of this work shows that the two end states in the morphodynamic continuum, which are the dissipative and reflective states, exhibit relatively small rates of cross-shore sediment transport and weak gradients in that transport which both ensure that the nearshore morphology is relatively stable. The intervening intermediate beach states typically exhibit prominent bar topographies and in these states, strong morphodynamic feedbacks between hydrodynamic processes and morphology create locally large transport rates and sharp transport gradients which is the reason for the dynamic nature of these beach states. Transport processes driving sediment onshore and offshore within beach states are discussed as well as the transport processes responsible for state transitions.