Fig. 7

Time series of vertical displacement derived by StaMPS-SBAS method and groundwater level changes at six wells during the period January 2018 and December 2022 in Zhengzhou city: (1) Huiji_1, (2) Huiji_2, (3) Zhongmu, (4) Erqi, (5) Xinzheng_1, and (6) Xinzheng_2 corresponding to the location (1)–(6) in Fig. 1. The grey bar indicates the daily rainfall schematic diagram, whose length corresponds to the daily precipitation, with a longer bar indicating heavier rain on that day. The red vertical bar represents the moment of the extreme rainstorm event in July 2021. All groundwater level changes in the graph are observed in well data.