Change in Longitudinal Profile Using Sand of Mixed Grain Size in Large Wave Tank and its Numerical Simulation

A contour-line-change model considering the sorting effect of grain size was applied to the prediction of the changes in longitudinal profile of a model beach composed of sand of mixed grain size. The results were compared with the experimental results using a large wave tank. The experimental results that sand of mixed grain size is sorted into fine and coarse sand, and that coarse sand is transported shoreward, forming a berm, whereas fine sand sinks into a zone deeper than the depth of closure h_c were accurately reproduced by the numerical simulation. Furthermore, the result that the formation of the berm is rapid, whereas seabed changes in the offshore zone are slow, was also reproduced by the numerical model. The results of the calculation of changes in the content rate indicated that an increase in the volume of coarse sand contributes to the shoreline advance as a result of berm formation, whereas an increase in the volume of fine sand accelerates the outflow of fine sand into a zone deeper than h_c.