title: Have GRACE satellites overestimated groundwater depletion in the Northwest India Aquifer?
abstract: The Northwest India Aquifer (NWIA) has been shown to have the highest groundwater depletion (GWD) rate globally, threatening crop production and sustainability of groundwater resources. Gravity Recovery and Climate Experiment (GRACE) satellites have been emerging as a powerful tool to evaluate GWD with ancillary data. Accurate GWD estimation is, however, challenging because of uncertainties in GRACE data processing. We evaluated GWD rates over the NWIA using a variety of approaches, including newly developed constrained forward modeling resulting in a GWD rate of 3.1 ± 0.1 cm/a (or 14 ± 0.4 km(3)/a) for Jan 2005-Dec 2010, consistent with the GWD rate (2.8 cm/a or 12.3 km(3)/a) from groundwater-level monitoring data. Published studies (e.g., 4 ± 1 cm/a or 18 ± 4.4 km(3)/a) may overestimate GWD over this region. This study highlights uncertainties in GWD estimates and the importance of incorporating a priori information to refine spatial patterns of GRACE signals that could be more useful in groundwater resource management and need to be paid more attention in future studies.
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Di
authors.initials: D
authors.lastname: Long
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78758, United States.
authors.forename: Bridget R
authors.initials: BR
authors.lastname: Scanlon
authors.affiliation: Department of Physical Geography, Utrecht University, Utrecht, Netherlands.|NASA Goddard Institute for Space Studies, New York, NY 10025, United States.|Center for Climate Systems Research, Columbia University, New York, NY, United States.|International Institute for Applied Systems Analysis, Laxenburg, Austria.
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Wada
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.|Department of Civil Engineering and Environmental Science, University of Oklahoma, Norman, OK 73072, United States.
authors.forename: Yang
authors.initials: Y
authors.lastname: Hong
authors.affiliation: Department of Biological &Agricultural Engineering, Texas A&M University, College Station, TX 77843, United States.|Department of Civil &Environmental Engineering, Texas A&M University, College Station, TX 77843, United States.
authors.forename: Vijay P
authors.initials: VP
authors.lastname: Singh
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China.
authors.forename: Yaning
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Cunguang
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Zhongying
authors.initials: Z
authors.lastname: Han
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Wenting
authors.initials: W
authors.lastname: Yang
mesh_terms: D055593:Geological Phenomena; D060587:Groundwater / Q000032:analysis*; D007194:India; D008962:Models, Theoretical; D018531:Spacecraft; D014780:Viruses