FLUID-SEDIMENT DYNAMICS IN THE NEARSHORE

The long-range goals of this program are to improve our understanding of the processes and physical mechanisms responsible for beach morphology changes and patterns of erosion and deposition in the nearshore zone. OBJECTIVES At present, three aspects of nearshore sediment transport are being investigated: 1) small-scale sediment transport, with emphasis on the initiation and vertical distribution of suspended sediment by turbulence and characterization of bottom boundary layer flows; 2) the linkage between small-scale sediment resuspension and large-scale flows (edge waves, shear waves and mean currents) which presumably lead to changes in nearshore morphology; and 3) large-scale morphology, with emphasis on the nearshore bathymetry of high energy, dissipative beaches in the Pacific Northwest. APPROACH The overall approach is to determine the fundamental relationships between fluid forcing and sediment response by conducting detailed field studies using instrumentation deployed within the surf zone. These measurements are used for direct sediment transport calculations, in addition to guiding development and evaluation of bottom boundary layer, fluid-sediment interaction models