Characteristics of Spatial and Temporal Evolution of Sandy Coastline in Shuidong Bay based on Remote Sensing Images

In this study, 77 periods of Landsat TM/OLI remote sensing image data of Shuidong Bay from 1987 to 2021 were used to extract the sandy shoreline of Shuidong Bay. A visual interpretation method was employed to analyze the sandy shoreline of this beach over the past 30 years. This involved examining the shoreline erosion or siltation, the linear or non-linear process of the beach, and the main patterns of beach evolution. A spatio-temporal evolution characterization study was conducted. The results demonstrated that: (1) The shoreline change of Shuidong Bay in the past 30 years is mainly stable (49.3%), with erosion or siltation occurring primarily in the middle and east side of the beach. The maximum siltation rate was 2.65 m/a, while the maximum erosion rate was -2.50 m/a. (2) There are three main evolutionary trends in Shuidong Bay. The evolution of Shuidong Bay can be divided into three main categories: linear, non-linear, and non-linear with a linear component. The linear process is primarily observed on the west side of the beach, while the non-linear process is concentrated on the south side. On the east side of the beach, the non-linear process is the dominant force shaping the shoreline. The linear process accounts for 61.2% of the total area. The first mode spatial coefficients of Suidong Bay are highly similar to the graphs of the LRR values, which further verify the main spatial pattern of the shoreline of Suidong Bay. This pattern can be described as a temporal reversal of the trend of siltation along the shoreline before 2003, followed by erosion along the shoreline after 2003. This paper presents an analysis of the evolution of the sandy coastline in Shuidong Bay. The results provide a valuable foundation for the development, utilization, management, and protection of coastal zone resources in Shuidong Bay.