Effect on Sand Supply to Foreshore by Beach Nourishment on the Miyazaki Coast

摘要

As a countermeasure for coastal erosion, beach nourishment has been enforced on the Miyazaki Coast, Japan. However, there is no information for the effect of beach nourishment on the coast. In this study, the effect on sand supply to foreshore by beach nourishment was examined using mineral analysis of sand. The sand samples were collected from beach nourishment area, coastal beach (water's edge and high water line) in front of the nourishment area, and beach cliff, immediately after construction of the nourishment. In addition, after 6 months the beach nourishment collapsed with big waves, we also investigated the sands at the same points. The characteristics of the sands were investigated using X-ray fluorescence and X-ray diffraction (XRD) analyses in order to trace sand movement. Cluster analysis was applied to the peak intensity ratios of XRD. The sands collected form the nourishment area and coastal beach were clearly distinguished just after construction of the beach nourishment. In contrast, a strong similarity was demonstrated between the sand collected form the nourishment area and coastal beach after 6 months. As these results, it is suggested the beach nourishment has an effect on sand supply to foreshore.