WAVE OVERWASH OF SUBAERIAL DUNES

Yukiko Tega, Nobuhisa Kobayashi

Abstract


Small-scale experimental results consisting of 72 runs for minor to major dune overwash are analyzed to improve existing dune erosion models that do not account for wave overwash processes explicitly. The measured cross-shore sediment transport rate is found to vary approximately linearly from the measured rate somewhat below the still water level, which is affected by the overwash intensity, to the overwash rate over the dune crest. The measured overwash sand concentration for the sand with its median diameter of 0.38 mm used in this experiment was in the range of 0.02 to 0.06. The time-dependent one-dimensional numerical model for the overtopping flow combined with two sediment transport formulas indicates that the overwash sand concentraion may be on the order of 0.04 except for very fine or coarse sands.

Keywords


dune; subaerial dune; overwash

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