Since 2014, a series of China's water resource management policies have been implemented to mitigate groundwater-induced land subsidence in the North China Plain (NCP). While previous studies have demonstrated the benefits of Synthetic Aperture Radar interferometry (InSAR) in providing policy-relevant insights into the spatio-temporal dynamics of subsidence and groundwater recovery, most have focused on localized regions, leaving the long-term impact of these measures across the entire NCP insufficiently evaluated. A key challenge is the variation of long-wavelength errors in each SAR frame, which results in inconsistencies in the subsidence velocity field over large areas. To address this issue, this paper proposes a machine learning-based adjustment approach for routinely wide-area subsidence mapping and then fully evaluating land subsidence and associated groundwater depletion in the NCP from the end of 2014 to 2022. The novelty of this method lies in the adaptive selection of the optimal model for each SAR frame, which minimizes the varying long-wavelength errors, rather than relying on a unified model for all SAR frames as commonly used in state-of-the-art approaches. Additionally, we mitigated the difference of InSAR measurement in the overlap regions between consecutive tracks caused by the varying incidence angles by incorporating GNSS data and a plate motion model. Using synthetic and real Sentinel-1 data, we validated the performance of the proposed method against prevalent approaches through an independent GNSS validation dataset, demonstrating accuracy improvements from 3.8-17.5 mm/yr to 2.0 mm/yr. The results indicated that approximately 56,882 km2 of the NCP area experienced land subsidence greater than 20 mm/yr. The central alluvial and coastal plains were the primary areas of subsidence, with a maximum cumulative subsidence of up to 2 m. The average subsidence velocity peaked in 2018 at 38.5 mm/yr. Subsidence has been alleviated after 2021. Our results revealed the lower bound of groundwater loss from the confined aquifer in the NCP, totaling 24.9 billion m3 between the end of 2014 and 2022. Of this total, 20.2 billion m3 (81 %) was lost from October 2014 to the end of 2020, with the loss decreasing to 4.7 billion m3 (19 %) during the period from January 2021 to December 2022. This study provides new evidence for China's groundwater management practices in addressing land subsidence in the NCP.
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