Numerical Simulation on Sand Accumulation behind Artificial Reefs and Enhancement of Windblown Sand to Hinterland

Abstract

Salients were formed in the lee of two artificial reefs (submerged breakwaters) constructed on Kimigahama Beach in Chiba Prefecture, Japan, owing to the wave-sheltering effect of the reefs, and then, a significant amount of fine sand was transported inland from the salients by wind action. In this study, not only shoreline changes after the installation of the two artificial reefs but also beach changes caused by windblown sand were predicted using a model, in which the BG model (a model for predicting three-dimensional beach changes due to waves based on Bagnold’s concept) is combined with a cellular automaton method. Reproduction calculation was carried out on the basis of field data. Beach changes after the artificial reefs were removed were also predicted and the effect of beach nourishment was investigated. It was concluded that landward sand transport by wind is accelerated when wave-sheltering structures such as an artificial reef are constructed on a coast composed of fine sand, and such an effect can be successfully predicted by using the present model.

Prediction of Topographic Changes on Enshu-Nada Coast Considering Effect of Both Waves and Windblown Sand

“…The calculation of beach changes and sand dune formation on the backshore was carried out using a model developed by Yokota et al (2022) for predicting three-dimensional (3-D) beach changes under combined actions of waves and wind. In this model, the beach changes due to waves occurring in the depth zone between the depth of closure (hc) and the berm height (hR) are predicted using the BG model (a model for predicting three-dimensional beach changes based on Bagnold's concept) (Uda et al, 2018), whereas topographic changes due to windblown sand in the area landward of a berm top are predicted by a cellular automaton method.…”

“…In the prediction of beach changes of this coast, the combined effect of waves and windblown sand must be considered. In this study, the topography of coastal sand dunes on coasts facing the Enshu-nada Sea was measured and topographic changes were calculated using a model for predicting the effect of both waves and windblown sand; the model was developed by Yokota et al (2022), with which they predicted the topographic changes due to the effect of both waves and windblown sand.…”