Publication Date:
2019-09-28
Description:
Relating Gravity Recovery and Climate Experiment (GRACE)derived terrestrial water storage anomaly (aTWS) variations to in situ groundwater data is important to understanding GRACE data utility. Here GRACEderived annual changes in aTWS (TWS) from National Aeronautics and Space Administration's Jet Propulsion Laboratory and Goddard Space Flight Center are compared to annual changes in saturated groundwater volumes (GW) in the High Plains aquifer (HPA) and overlying alluvial aquifers in Kansas. Regression analysis suggests that trends in TWS are strongly related to trends in GWalluvial and weakly related to trends in GWHPA, although the magnitude of TWS is much larger than GWalluvial and is similar to GWHPA. Unlike alluvial aquifers, a thick vadose zone overlies the HPA. Estimates of changes in vadose zone water content (VZ) using GRACE products are similar in magnitude to annual variations in North American Land Data Assimilation soil moisture data, suggesting an unexpected dominance of VZ in TWS despite significant groundwater depletion. Results demonstrate that water storage changes in shallow alluvial aquifers, the root zone, the deep vadose zone, and the HPA itself are all significant in the HPA region of Kansas. Consequently, GRACE observations cannot, alone, be taken to reflect variations in saturated zone groundwater storage in the HPA, or other large, heavily used aquifers subject to substantial groundwater depletion, when deep unsaturated zones exist. GRACE can best provide guidance on regional aquifer storage changes where water storage changes in the vadose zone and perched or adjacent aquifers are well constrained.
Keywords:
Earth Resources and Remote Sensing
Type:
GSFC-E-DAA-TN60582
,
Water Resources Research (ISSN 0043-1397) (e-ISSN 1944-7973); 54; 10; 8034-8044
Format:
application/pdf
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