PERFORMANCE OF PERCHED BEACH NOURISHMENTS

[摘要] Perched beach nourishments are popular measures to contrast beach erosion in the presence of steep beaches. Inspired by a real case-study, in the present work the performance of two configurations of the submerged barrier used to protect the toe of the beach are experimentally investigated. Measurements have been gathered concerning wave reflection and transmission, stability and scours around the submerged sill, and beach profile evolution. Both accretive and erosive wave conditions have been considered here. A comparative analysis on the evolution of the two configurations of the sill, shows that the armoring of the filter behind the rubble mound structure is a very effective measure to increase the level of beach protection (e.g. the shoreline retreat under erosive wave attack is reduced to a third). The comparison of the experimental results with an analytical model to predict the equilibrium profile of perched beaches shows that the key phenomena controlling the process are related not only to wave reflection but also to wave dissipation mechanisms at the sill. Moreover, the comparison of the experimental results with field data proves that notwithstanding the several simplifying assumptions considered in the physical modeling, several phenomena are reasonably predicted by the model (e.g. beach evolution, stability and scours).

[学科分类] 建筑学

[关键词] equilibrium profile;submerged breakwater;accretive waves;erosive waves