Large-scale high-resolution coastal subsidence mapping in eastern China with Sentinel-1 and Sentinel-2: Heterogeneous patterns and primary drivers

• We reveal coastal subsidence pattern in eastern China with Sentinel-1 TS-InSAR. • We develop a novel method for coastal multi-frame interferogram mosaicking. • Several heterogeneous subsidence funnels are detected. • Human activities are the primary driver of coastal subsidence. • Subsidence funnels are mainly controlled by single-factor. A majorty of the low-lying coastal areas worldwide, where the population is densely concentrated, are confronted with high to extremetly high risks of land subsidence. However, a comprehensive detection and quantification of large-scale coastal subsidence patterns and their primary drivers in eastern China remain lacking. In this study, we employed Time Series Interferometric Synthetic Aperture Radar (TS-InSAR) technique and Sentinel-1 data to derive the vertical deformation pattern at a resolution of 90 m from 2017 to 2024. We developed a novel multi-frame mosaicking method, achieving spatially consistent InSAR observations over the land-sea transition areas. Our findings uncover extensive coastal subsidence in northeastern Shandong and eastern Jiangsu, highlighting several rapid-subsidence funnels with rates exceeding 50 mm/yr for the first time. By integrating Sentinel-2 multispectral imagery, subsidence time series, groundwater level measurements, and principal component analysis (PCA), we further analyzed the spatiotemporal distribution patterns and underlying drivers of these heterogeneous subsidence funnels. Our analysis demonstrates that anthropogenic factors are the dominant drivers of coastal subsidence. Four representative case studies reveal distinct subsidence mechanisms: (1) brine extraction for salt production and aquaculture, (2) excessive freshwater withdrawal for agricultural irrigation and industrial use, (3) groundwater depletion for intensive greenhouse aquaculture, and (4) land reclamation for industrial infrastructure development. In each region, subsidence patterns are predominantly controlled by a single dominant factor. This study is expected to provide valuable insights for monitoring and managing coastal subsidence, enhance our understanding of associated risks, and offer critical guidance for protecting communities in vulnerable coastal areas.