Présentations Colloques

    Oral Presentation
    8.11
    Session 8.11: Hydrogeodesy: new surface tools to characterize and monitor active and managed groundwater systems
    Feng Wei
    Groundwater storage variations in the North China Plain from GRACE and ground observations
    Extensive anthropogenic activities in the North China Plain (NCP), such as agricultural irrigation and urbanization, are consuming the unrecoverable groundwater resource in the region. Since its launch in 2002, the Gravity Recovery and Climate Experiment (GRACE) satellites provide a powerful tool to monitor regional groundwater storage (GWS) variations. In this study, we provide a detailed assessment of spatiotemporal variations of groundwater storage in the NCP from two independent methods, i.e., GRACE satellite measurements and ground well observations. Based on GWS estimates from GRACE and ground observations, seasonal groundwater variations in the NCP respond to the additive effect of anthropogenic irrigation (discharge of groundwater aquifers from spring to summer) and natural precipitation (recharge of groundwater aquifers from summer to winter). On inter-annual timescales, groundwater changes from GRACE and ground observations agree well with year-over-year precipitation anomalies. However, for the whole period of 2002-2014, the spatial pattern of GRACE-based long-term groundwater depletion rates indicates significant mass loss in the piedmont and central plain regions of NCP, while ground well observations only indicate the groundwater level decrease of shallow unconfined aquifers in the piedmont region, i.e., the western part of NCP. The difference in groundwater depletion rate estimates from GRACE and from ground observations indicates the significant contribution from deep aquifers in the central plain of NCP, which was underestimated until now. Furthermore, the GNSS network in the NCP observes the significant ground subsidence in the central plain of NCP, which results from the groundwater depletion in confined aquifers. Although GRACE cannot distinguish the different GWS variation behavior between the shallow and deep aquifers in the NCP, we still successfully isolate these two contributions to the long-term GWS depletion by combing GRACE, ground well observations and GNSS measurements.
    China

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