title: Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing.
abstract: The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined.
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. jmguo@sgg.whu.edu.cn.|Key Laboratory of Precise Engineering and Industry Surveying of National Administration of Surveying, Mapping and Geoinformation, Wuhan University, Wuhan 430079, China. jmguo@sgg.whu.edu.cn.|Guangxi Key Laboratory of Spatial Information and Geomatics, Guilin University of Technology, Guilin 541004, China. jmguo@sgg.whu.edu.cn.
authors.forename: Jiming
authors.initials: J
authors.lastname: Guo
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. zhoulv_whu@163.com.|Key Laboratory of Precise Engineering and Industry Surveying of National Administration of Surveying, Mapping and Geoinformation, Wuhan University, Wuhan 430079, China. zhoulv_whu@163.com.|Guangxi Key Laboratory of Spatial Information and Geomatics, Guilin University of Technology, Guilin 541004, China. zhoulv_whu@163.com.
authors.forename: Lv
authors.initials: L
authors.lastname: Zhou
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. clyao@whu.edu.cn.|Guangxi Key Laboratory of Spatial Information and Geomatics, Guilin University of Technology, Guilin 541004, China. clyao@whu.edu.cn.
authors.forename: Chaolong
authors.initials: C
authors.lastname: Yao
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China. plgk@whu.edu.cn.
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Hu
keywords: Beijing; GRACE; groundwater; multi-temporal InSAR; surface subsidence