DEPTH OF SAND ACTIVATION ON PROTECTED AND NON-PROTECTED NOURISHED BEACHES: A LABORATORY STUDY IN A LARGE-SCALE WAVE FLUME

摘要

The depth of sand activation on a beach under the action of waves is a key parameter for many scientific and applied projects in coastal engineering. Although there is a good literature on field studies, the work presented here represents the first laboratory study of its kind. Two nourished beaches from the Venice barrier-island system (Pellestrina and Cavallino) were reconstructed in a large wave flume and sediment activation was studies using trenches filled with colored sand. The results confirm the control by Significative Wave Height (Hs) and Peak Wave Period (Ts). The spatially averaged Sediment Mixing Depth (Zm) resulted to be respectively 20% of Hs and 8% of Tp. In the case of the beach protected by a breakwater (Pellestrina) wave steepness resulted to be an additional indicator, possibly because of variable transmission rates over the structure.