title: Earth surface deformation in the North China Plain detected by joint analysis of GRACE and GPS data.
abstract: Mass redistribution of the Earth causes variable loading that deforms the solid Earth. While most recent studies using geodetic techniques focus on regions (such as the Amazon basin and the Nepal Himalayas) with large seasonal deformation amplitudes on the order of 1-4 cm due to hydrologic loading, few such studies have been conducted on the regions where the seasonal deformation amplitude is half as large. Here, we use joint GPS and GRACE data to investigate the vertical deformation due to hydrologic loading in the North China Plain, where significant groundwater depletion has been reported. We found that the GPS- and GRACE-derived secular trends and seasonal signals are in good agreement, with an uplift magnitude of 1-2 mm/year and a correlation of 85.0%-98.5%, respectively. This uplift rate is consistent with groundwater depletion rate estimated from GRACE data and in-situ groundwater measurements from earlier report studies; whereas the seasonal hydrologic variation reflects human behavior of groundwater pumping for agriculture irrigation in spring, leading to less water storage in summer than that in the winter season. However, less than 20% of weighted root-mean-squared (WRMS) reductions were detected for all the selected GPS stations when GRACE-derived seasonal deformations were removed from detrended GPS height time series. This discrepancy is probably because the GRACE-derived seasonal signals are large-scale, while the GPS-derived signals are local point measurements.
authors.affiliation: School of Water Resources and Hydropower Engineering, Wuhan University, 8 Donghu South Road, Wuhan 430072, China. lrlwuhan@gmail.com.
authors.forename: Renli
authors.initials: R
authors.lastname: Liu
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China. jcli@sgg.whu.edu.cn.
authors.forename: Jiancheng
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China. xshhuo@sgg.whu.edu.cn.
authors.forename: Hok Sum
authors.initials: HS
authors.lastname: Fok
authors.affiliation: School of Earth Sciences, Ohio State University, 275 Mendenhall Lab., 125 S. Oval Mall, Columbus, OH 43210, USA. ckshum@osu.edu.
authors.forename: C K
authors.initials: CK
authors.lastname: Shum
authors.affiliation: Faculté des Sciences, de la Technologieet de la Communication, University of Luxembourg, L-1359 Luxembourg. zhao.li@uni.lu.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Li
mesh_terms: D057914:Agricultural Irrigation; D002681:China; D018534:Earth, Planet; D004784:Environmental Monitoring; D040362:Geographic Information Systems; D006801:Humans; D062070:Hydrology; D012621:Seasons; D014881:Water Supply