Abstract
The percolation effect of the foreshore composed of the combined layers of gravel and sand was investigated by a movable bed experiment using a wave tank. The grain size was selected to be d = 0.3, 1 and 3 mm. Under the condition that the grain size of upper layer is kept constant as d = 1 mm and the grain size of the lower layer is d = 0.3, 1 and 3 mm, berm height decreased with the coarser grain size, resulting in the reduction in wave run-up height due to the percolation effect. This implies that the formation of gravel layer of grain size larger than the ordinary gravel nourishment is effective.
