Sediment mixing-depths on a low-energy reflective beach

A field experiment was conducted on a sandy, micro-tidal, estuarine beach at Fire Island, New York, USA to determine the maximum depth of sediment mixing by waves and currents on a low-energy, reflective beach. Mixing depth was measured during three experiments using fluorescent-tracer sands injected across the upper foreshore at high water. The average mixing depth for this environment during these experiments was about 22% of significant wave height. Wave-based models for high-energy beaches underestimate the average, maximum mixing-depth by as much as 400%. The cross-shore distribution of mixing depth shows a maximum at the breakpoint associated with breaker-generated turbulence in the swash. -from Authors