BEACH CHANGES OF NOURISHMENT MOUND FORMED BY SAND BACK PASS ON AJIGAURA BEACH

Abstract

 Deformation of sand mound formed by beach nourishment associated with a sand back pass was investigated at Ajigaura Beach. The erosion process of the sand mound and the deposition of the material owing to waves were investigated. UAV images were taken on 16 July 2021 immediately after the nourishment and 15 October 2021, and three-dimensional beach topographies were measured together with the field observations on the conditions of the beach. Nourishment sand was quickly transported again in a short period while losing the effect, and entire nourishment sand was transported away from the nourishment site after three months, implying the inefficiency of the present method. After the improvement, by which nourishment sand is stably maintained at the nourished beaches, beach nourishment should be carried out.