SAND SORTING AND TOPOGRAPHY CHANGE OF BEACH COMPOSED OF BI-MODALLY-DISTRIBUTED SAND

Characteristics of topography change of the beach consisted of bi-modally distributed bed materials and sorting process of bed material were investigated through experiments in the field and in the laboratory. It is found that the value of median grain size d₅₀ did not become a parameter to classify the type of topography change from field and laboratory experiments. The authors examined the applicability of a so-called multi-fraction approach for evaluating cross-shore sediment transport rate measured in the laboratory and found that it did not perform well without the information of the thickness of mixing in the bottom.