Spatial Patterns of Sandy Beaches in China and Risk Analysis of Human Infrastructure Squeeze Based on Multi-Source Data and Ensemble Learning

Abstract. Sandy beaches provide essential ecological and economic services, but their functions are increasingly threatened by human activities. Analyzing the spatial distribution of China's sandy beaches and the impacts of human activities offers valuable insights for coastal resource management and ecological protection. However, remote sensing technologies face challenges such as limited data sources and tidal influences, which affect recognition accuracy. Therefore, integrating multi-source remote sensing data and reducing the impact of tidal fluctuations to improve recognition accuracy remains a key challenge. This study proposes an innovative approach utilizing multi-source data and an ensemble learning model to identify sandy beaches in China (2016–2023). By integrating Sentinel-1/2 satellite data, terrain data, and nighttime light data, along with spectral, terrain, texture, and polarization features, sandy beaches were identified across multiple years, and the results were consolidated into a single-year dataset to analyze spatial patterns and risks from human infrastructure squeeze. (1) High-precision classification identified 2984 sandy beaches in China, covering a total area of 260.70 km². Guangdong had the largest number, area, and perimeter, while Shanghai had the widest sandy beaches. (2) In Fujian, Guangdong, and Taiwan, the identified sandy beaches covered 149.68 km², with perimeters of 5155.91 km and widths of 49.50 m, 32.83 m, and 50.70 m, respectively. These results were significantly better than those from reference datasets. (3) From 1990 to 2023, the area at risk from human infrastructure squeeze increased from 109.95 km² to 245.58 km², a rise of 135.63 km², with the most significant increase occurring between 1990 and 2000. Guangdong and Fujian showed growth rates of 1.05 km²/year and 0.73 km²/year, respectively. This study provides an up-to-date dataset on China's sandy beaches. It assesses their spatial patterns and human impact risks, contributing to research and policy for the sustainable development of coastal zones (https://doi.org/10.5281/zenodo.15307240, Meng et al., 2025).