English

SEDIMENT DYNAMICS OF BEACH BREACHING

Beach breaching is a rapid morphological change to a littoral system where rapid sediment transport creates a new tidal or riverine channel, altering the hydrodynamic response of the region. The dynamics of breaching are difficult to quantify in the field due to uncertainty of environmental forcing parameters. Therefore, this study was done in a controlled laboratory using a small-scale beach model and image processing. The hypothesis tested was that water inflow rates, equivalent to river discharge in the field, control breach behavior. By altering the flow rates during lab simulations, three dynamics of breaching were observed. Fast flow rates led to overtopping. Intermediate flow rates caused slumping within the slope that is followed by overtopping. Last, very slow flow rates produced steady state seepage, and the lab beach did not breach. This research has led to the determination that breaching is not only impacted by just the increase in water on river or ocean side, but that the rate of filling is crucial in determining breaching characteristics.

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