Abstract: Land subsidence is a prominent geological hazard in the Beijing area, posing a serious threat to the sustainable development of the economy, environment and society. This paper takes the Chaoyang-Tongzhou area, which is a severely subsiding region of the Beijing Plain, as the research object. Based on Sentinel-1 A/B satellite track data and using PS-InSAR (persistent scatters InSAR） technology, the characteristics of land subsidence in the study area from 2019 to 2021 was obtained. The dynamic time warping (DTW) algorithm was used to quantitatively analyze the response relationship between land subsidence and groundwater levels at different depths, and then the contribution rate of groundwater at different depths to subsidence was quantified. The results show as follows: 1) From 2019 to 2021, land subsidence in the Chaoyang-Tongzhou area developed continuously. The most severe subsidence areas with an annual subsidence rate exceeding 50 mm/a were mainly distributed in the east of Chaoyang and the north of Tongzhou, and the maximum subsidence rate of 91 mm/a. 2) The difference in regional distribution of compressible layer thickness in the Chaoyang-Tongzhou area provids favorable geological conditions for the occurrence and development of land subsidence. On the whole, the thickness of the compressible layer is positively proportional to the land subsidence rate. The thickness of compressible layer at the location of PS points with a land subsidence rate greater than 80 mm/a in the study area was greater than 180 m, mainly in areas with a compressible layer thickness of 200-220 m. 3) Land subsidence responds differently to groundwater level time series at different depths. The water level in the confined aquifer with a burial depth of 50-180 m has a relatively high response degree to land subsidence, with the groundwater level at depths of 92.00 m and 121.42 m showing the highest response degree to land subsidence time series, reflecting that the groundwater level changes at this depth are the main inducing factors for subsidence.

Key words: land subsidence, PS-InSAR, DTW, Chaoyang-Tongzhou area, groundwater level, influence factors；Beijing