A laboratory experiment was conducted in a wave flume to observe and measure sand suspension events under shoaling waves on a rippled bed and under breaking waves and bores on an equilibrium terraced beach consisting of fine sand. The same irregular waves were generated for 37 tests to measure the three-dimensional velocities and concentrations at several elevations above the local bed at five cross-shore locations. The measured alongshore velocity is shown to be about 20% of the cross-shore velocity and an effective proxy for detecting three-dimensional vortices and turbulence near the rippled bed and inside the surf zone. The spectra of the alongshore velocities inside the surf zone were dominated by low frequency components associated with intermittent irregular wave breaking. The measured sand concentrations were dominated by intermittent suspension events accompanied by large fluctuating alongshore velocities. Intermittent suspension events occurred under the steep fronts of breaking waves with large fluid accelerations. Strong plunging breakers occurring intermittently caused very intense suspension events lasting at least several seconds. Moderate suspension events were also observed under uprushing bores. The time-averaged sand fluxes on the equilibrium beach calculated from the measured time series were relatively small and not accurate enough to explain the equilibrium profile.
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