Accelerated coastal subsidence variability across the yellow river delta due to anthropogenic land use and land cover changes over the last two decades

The Yellow River Delta (YRD), one of the world’s significant river deltas, undergoes substantial surface transformations driven by a variety of factors. This study integrates optical and Synthetic Aperture Radar imagery, geophysical models, and hydrogeological data to analyze the spatiotemporal patterns, evolutionary characteristics, and mechanisms of surface change in the YRD’s coastal zones. Using Small Baseline Subset Interferometric Synthetic Aperture Radar techniques and Random Forest algorithms, the study examines surface deformation and land use/land cover transformations over the past 20 years. Areas with significant subsidence, especially in coastal regions, show annual rates of up to 20 cm. Anthropogenic landscapes in the YRD have expanded from inland to coastal areas, with notable growth in land cover types such as wetlands, forests, halophytes, aquaculture ponds, and salt fields. Quantitative spatiotemporal analysis shows that human activities, particularly brine extraction in salt fields, are major drivers of surface subsidence. The study’s optimized contraction source model, with a maximum vertical contraction of 18 cm/yr, provides a quantitative evaluation of subsidence mechanisms and brine aquifer changes. In conclusion, this research offers novel insights into the spatiotemporal dynamics and evolution of surface changes in major river deltas, presenting new perspectives and empirical evidence on the mechanisms driving subsidence in coastal zones.