Suspended and Bedload Transport in the Surf Zone: Implications for Sand Transport Models

Abstract

This paper presents results obtained during a large-scale wave flume experiment focused at measuring hydrodynamics and sediment transport processes in the wave breaking region. The experiment involved monochromatic plunging breaking waves over a mobile bed barred profile consisting of D 50 = 0.24 mm sand. Vertical profiles of velocity, turbulence, sand concentration and sand fluxes were measured at 12 cross-shore locations, covering the shoaling region up to the inner surf zone. Particularly high-resolution profiles were obtained near the bed within the wave bottom boundary layer, using an acoustic sediment concentration and velocity profiler (ACVP). Sheet flow concentration and particle velocities were measured at two locations near the bar crest using two conductivity-based concentration measurement tanks (CCM+). Total transport rates, obtained from the evolving bed profile measurements, were decomposed into suspended and bedload transport contributions across the bar. The present paper presents a summary of the key findings of the experiment, which are used to discuss existing approaches for modeling suspended and bed load transport in the surf zone.

Benthic Species Distribution Linked to Morphological Features of a Barred Coast

“…Strong tidal currents and wave action reach the bottom and stir up fine particles of sediment and organic matter. Morphological features, such as bars and troughs, interact with the waves and tidal flows, causing wave breaking and more stirring up of the sediment [28,32]. The coarser particles end up at the beach and the finer particles are brought to slightly deeper and calmer water just outside the breaker-zone.…”

“…Then the water retreats and accelerates in offshore direction (rundown or backwash). The process of wave shoaling and wave breaking creates mean water level gradients that induce wave-driven currents, both cross-shore (undertow), longshore, and in cell circulations (rip currents) transporting suspended sediment, organic matter, other materials, and small organisms [25,28,29]. The position of nearshore bars and troughs varies alongshore and over time.…”