Nonlinear modelling of shoreface-connected ridges; Impact of grain sorting and interventions

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• 作者：H.E. de Swart ; M. Walgreen ; D. Calvete ; N.C. Vis-Star
• 关键词：Sand ridges ; Inner shelf ; Morphodynamics ; Spectral method ; Sediment transport
• 刊名：Coastal Engineering
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：55
• 期：7-8
• 页码：642-656
• 全文大小：1933 K

文摘

The evolution of shoreface-connected sand ridges on micro-tidal inner shelves and the variations in the mean grain size over these ridges are investigated with process-based models. A review of previous studies is presented, as well as new results that concern the influence of grain sorting on the finite-amplitude behaviour of the ridges, the application of the model to La Barrosa beach and the role of wave-topography feedbacks. The ridges initially form due to morphodynamic self-organisation, in which the presence of waves and a storm-driven current are crucial. Predicted growth time scales, migration speeds, topography and spatial pattern of the mean grain size agree with field data collected on micro-tidal shelves in the case that both bedload and suspended load sediment transport are accounted for, together with spatially non-uniform wave orbital motion. The model can not successfully explain the presence of large-scale ridges observed on La Barrosa inner shelf, because strong and complex behaving tidal currents occur in that area.