The West Pearl River Delta (WPRD) region is experiencing land subsidence due to the combined effect of natural and anthropogenic factors. This study investigates the concern of land subsidence in the region, attributed to rapid urbanization and tremendous population growth over the past few decades. A comprehensive subsidence analysis of sixty-seven Sentinel-1 images, acquired between 2016 and 2021, using the persistent scatterer interferometry technique (PSI), has been conducted to monitor and reveal the ground subsidence characteristics in the WPRD.

The findings indicate a range of overall vertical deformation velocities in the WPRD, varying between -70 mm/year and 10 mm/year. Notably, three distinct subsidence bowls have been identified in the study area, including Gaolan Island in Zhuhai, the junction area of Zhuhai and Zhongshan, and the junction area of Zhongshan and Jiangmen. Spatial-temporal subsidence patterns have been analyzed, revealing that ground subsidence is predominantly observed in Quaternary deposits and closely related to sediment thickness. This association underscores the significant contribution of soft soil consolidation to land subsidence in the region.

Furthermore, land use maps for 2016 and 2021 were generated utilizing Landsat-8 images to examine the relationship between land subsidence and land use. The analysis reveals that rapid subsidence occurs primarily in aquaculture, urban, and agricultural areas, with higher rates observed in regions undergoing substantial land use conversions driven by human activities. To predict subsidence rates, a Random Forest Regression (RFR) model incorporating influential factors such as soft soil thickness, groundwater exploitation, land use, elevation, and strata lithology was employed. The RFR model demonstrated favorable predictive performance (R² = 0.631, RMSE = 2.7 mm/year). Importance assessment of these influencing factors based on the RFR algorithm revealed that soft soil thickness, elevation, groundwater exploitation, strata lithology, and landcover type are the most significant factors affecting subsidence.

Moreover, the applicability of geological data and land-use history for land subsidence prediction was demonstrated through the utilization of the RFR algorithm. Finally, a comprehensive land subsidence risk assessment was conducted by combining information on land subsidence hazard and vulnerability. The results identified high-risk regions and sub-high-risk regions of subsidence, covering an area of 17.93 km² and 123.52 km², respectively, which account for 0.4% and 2.77% of the total evaluated region. These regions are primarily concentrated in Zhuhai City, Zhongshan City, and Jiangmen City.

This study provides crucial insights and serves as a valuable reference for the prevention and management of land subsidence in the West Pearl River Delta region.

Prof. Ng is a Professor in Guangdong University of Technology. He completed his Bachelor's and Master's degree in Electrical Engineering in University of New South Wales, Australia, and continued his doctoral study in Department of Surveying and Spatial Information System. In June 2011, he obtained his doctoral degree. From November 2010 to December 2016, he worked in University of New South Wales in the Department of Surveying and Spatial Information System and Department of Civil and Environmental Engineering as a research associate and was mainly engaged in satellite remote sensing image analysis method and its application, InSAR algorithm and software development, ground subsidence monitoring and modeling, image classification. In 2017, he joined Guangdong University of Technology and has since been working there.

Prof. Ng has published more than 80 articles in international journals and conferences. In addition, he has presided over and participated in a number of national and provincial research projects. His research papers have received more than 900 citations according to the Web of Science database, resulting in an h-index of 18. Prof. Ng has been actively engaged in various research projects. He has led or participated in research projects supported by the National Natural Science Foundation of China, the Discovery Fund of the Australian Research Council, the Natural Science Foundation of Guangdong Province, etc. In addition to his research and teaching achievements, Prof. Ng serves as Associate Editor for the SCI journal "Frontiers in Earth Science" and as an editorial board member for the journal "Remote Sensing."