2024 Volume 80 Issue 17 Article ID: 24-17114
In the previous study, a two-dimensional movable bed experiment was carried out under the condition that bed rocks were buried under the gravel beach, while changing the location of the bed rocks and the thickness of the gravel layer. The critical thickness of the gravel layer in determining whether gravel is deposited on the foreshore or not was determined together with the classification of the types of the deposition on the foreshore. In this study, the mechanism that an equilibrium slope of the beach corresponding to the thickness of the sand layer becomes gentle when a rocky bed is buried under the beach was included in the BG model (a model for predicting 3-D beach changes based on Bagnold’s concept), and a model for predicting longitudinal profile of the beach was proposed, referring the results of the previous experimental study. In the reproduction calculation, when the thickness of the gravel layer is small, it was confirmed that offshore movement of gravel is intensified because the seepage flow is weak and the return flow over the rocky bed is accelerated.
