Aquifer restoration in the Lubei Plain, China: Insights from InSAR and groundwater head monitoring

Although groundwater levels (GWL) have gradually stabilized and even increased in some regions under human intervention, persistent land subsidence remains a concern. This situation underscores the urgent need to investigate the restoration mechanisms of the aquifer system, particularly focusing on the interconnected processes of groundwater dynamics and strata deformation. This study specifically concentrates on the Lubei Plain in the southeast of the North China Plain—a chief recipient area of the East Route of the South-to-North Water Diversion Project—to delve into these scientific inquiries. In this study, we utilize a limited amount of GNSS data to address InSAR atmospheric errors and employ a weighted least squares time series inversion method to enhance the robustness of the deformation time series. Furthermore, a blind source separation technique named Independent Component Analysis (ICA) is applied to separate mixed signals of InSAR, successfully isolating deformation signals from both the sand and clay layers within the aquifer system, as well as those induced by environmental loadings. These approaches significantly facilitate the exploration of the interactive processes between groundwater dynamics and strata deformation. The result reveals a complex relationship between GWL and surface deformation during the aquifer system’s recovery stage due to the distinct responses of the sand and clay layers to groundwater dynamics. We find that during the restoration phase of aquifer system (when recharge exceeds discharge), the sand layers undergo recovery and rebound firstly, while weakly permeable clay layers continue to consolidate.