Characterizing Aquifer Properties and Groundwater Storage at North China Plain Using Geodetic and Hydrological Measurements

Climatic and anthropogenic changes are reshaping global water resources, with the North China Plain (NCP) experiencing significant surface subsidence due to severe groundwater overexploitation over the past half-century. In this study, we integrate data from Interferometric Synthetic Aperture Radar, Global Navigation Satellite System, and hydraulic head measurements observed in 2015-2019 to investigate aquifers' physical properties and corresponding changes in groundwater storage in NCP. Geodetic measurements indicate seasonal and long-term deformation patterns. The amplitude of seasonal variation of deformation is up to 25 mm with phase lag behind the seasonal variation of water head. The integration of geodetic and hydrological data indicates that local aquifer storativity and clay lens thickness are 0.67x10-3-14.38x10-3 $0.67\times {10}<^>{-3}-14.38\times {10}<^>{-3}$ and 0.15-1.98 $0.15-1.98$ m, respectively. The average long-term subsidence due to sustained water storage loss is about 29 mm/yr, with a peak rate of similar to 120 mm/yr. Even though all regions show a long-term ongoing subsidence, the subsidence trend has slowed in about half of the NCP, which can be attributed to the impact of the South-to-North Water Diversion (SNWD) Project, especially in areas near the SNWD aqueducts. Moreover, we find a disparity in subsidence rates between Hebei and Shandong Provinces, reflecting the impact of different groundwater exploitation management in mitigating the subsidence. This research underscores the effectiveness of combining geodetic and hydrological data for assessing groundwater circulation and optimizing groundwater management.