| In South China where headland-bay beaches are commonly developed along the coast and many beaches are currently facing erosion problems, the study of the erosion and accretion evolution characteristics and mechanisms of headland bay beaches has important practical significance. This study took Qianjiang Bay in the south of Nan’ao Island, an important tourist island in Guangdong Province, as the research area. On the basis of beach surveys, remote sensing image data, historical charts and measured water depth data, this study conducted research on the beach erosion and accretion characteristics from 1970 to 2022. This study also explored the impact of human activities on the beach evolution from the aspects of the hydrodynamics, the longshore sediment transport, and the equilibrium embayment planform. The results showed that, the beach evolution of Qianjiang Bay showed different spatial characteristics before and after the construction of the pier breakwaters along the southeast coast. The tangent bank section was eroded in the early stage and the erosion was intensified in the later stage, the arc bank section was silted in the early stage and eroded in the later stage. The change in the position of the headland and the obstruction of the longshore sediment transport caused by the human coastal projects were the main mechanisms affecting the beach evolution, causing the unstable planform of the headland-bay beach coastline. The loss of regional sediments also aggravated the coastal imbalance. The longshore sediment transport from east to west controlled the spatial characteristics of the coastline evolution. |
