Tri-decadal evolution of land subsidence in the Beijing Plain revealed by multi-epoch satellite InSAR observations

The persistent land subsidence in the Beijing Plain induced by the massive exploitation of groundwater caused significant decreases in ground elevation and damages to buildings and civil infrastructures. Although various satellite SAR datasets have been analyzed to monitor subsidence in the Beijing Plain, no multi-decadal scale deformation measurement has been derived from multi-sensor InSAR results, and the recent deceleration of land subsidence or even uplift remains unclear. This study retrieved land subsidence measurements over the past three decades (1992–2022) by integrating multi-sensor C-band InSAR measurements into a logistic model. The cumulative subsidence presented three major subsidence funnels surrounding downtown in the North, Northeast, and East, with the maximum vertical displacement as high as 1.98 m in the Chaoyang District. The land subsidence positively responded to the changes in groundwater depth, showing a clear deceleration since 2016. After five and half years, it became almost stagnated within the context of continuous groundwater recovery, which implied the delayed compaction of lowly draining aquitards. Only slight residual subsidence persisted in Chaoyang, Shunyi, and Daxing Districts. Meanwhile, land uplift happened in Shunyi, Huairou, and Pinggu Districts. Remarkably, a portion of the land subsidence in the Chaobai Plain reversed to uplift due to multiple artificial recharges using diverted water. Although groundwater storage could recover significantly in the next decade, most severely sunken lands and inelastically compacted aquitards are irrecoverable, leading to a permanent loss of storage capacity in the Beijing Plain. This study provides scientific data support for the local government decision-maker to better manage groundwater resources and mitigate land subsidence, which presents a typical example of monitoring long-term land subsidence in similar global megacities.