Multi-Timescale Analysis of the Evolution of Sandy Coastline: A Case Study in South China

The coastal zone is essential to economic and social development. However, coastline evolution is a complex research topic, owing to the intersection and coupling of different fields such as wind, wave, and current. Research is further complicated by variations in these fields’ temporal and spatial scales. This study acquired and preprocessed multi-phase Landsat remote sensing satellite images of the eastern coast, from Wailuo to Zhuzi, from 1987 to 2021. Then, the decoded and extracted instantaneous coastline images were corrected, and quantitative analysis was carried out through the Digital Coastline Analysis System (DSAS). The results showed that trends of coastline evolution in the study area in the medium–long term were overall balanced. All the transects manifested temporal and spatial differences, and erosional hot spots were mainly concentrated on the coastal cape and its vicinity. To investigate storm-induced beach erosion in the short term, the 400 m coastline of Baimao in the area was selected as a field site, and the field survey was conducted during two storms. The distribution of the dynamic parameters of sediment deposition was also investigated. The results showed that the beach in the field site had an excellent ability to resist storm erosion and that the topographic change was greatly affected by geological conditions in the area, such as reef masking and a typical headland beach. The grain size parameters of the beach sediments were sensitive to storms, reflecting the adjustment of the beach surface during typhoons. This study shows how a multi-timescale analysis could represent an efficient approach to understanding the dynamic evolution of the coastline. It showed a detailed description of the historical coastline evolution of the eastern coast of the Leizhou Peninsula after 1987. Additionally, the coastline evolution and sediment distribution for the sedimentation dynamic environment of Baimao tourist area in the short term were also investigated. In conclusion, this study can contribute to the rational utilization of coastal resources, to coastal disaster prevention, and the mitigation of local coastal areas.