Morphodynamics of High Energy Beaches and Surf Zones: A Brief Synthesis.

Abstract : A short, simplified synthesis of some results obtained over the period 1979-1982 from a study of beach and surf zone dynamics is presented. The report deals with the different natural beach states, the process signatures associated with these states, state dependent modes of beach erosion, the status of predicting wave and surf-induced sediment suspension, environmental controls on modal beach state, and the temporal variability of beach state and beach profiles. Hydrodynamic processes and the relative contributions of different mechanisms to sediment transport and morphologic change differ dramatically as functions of beach state, that is depending on whether the surf zone and beach are reflective, dissipative or in one of the several intermediate states. Depending on beach state, near bottom currents show variations in the relative dominance of motions due to: incident waves, subharmonic oscillations, infragravity oscillations, and mean longshore and rip currents. (Author)