Use of GRACE Satellites to Assess Trends in Groundwater Storage Globally
Résumé
GRACE satellite data have proved invaluable in providing data on spatiotemporal variability in water storage at a global scale. While estimates of total water storage are relatively straightforward in large scale basins, disaggregating the groundwater storage component is complicated because of uncertainties in other components of the water budget. In this presentation we will discuss results of GRACE analysis on groundwater storage in different systems, ranging from simple unconfined aquifers with little surface water interactions (e.g. High Plains aquifer) to more complicated unconfined/confined aquifers with combined surface water and groundwater based irrigation (U.S. Central Valley and N India) systems. We will discuss different approaches for estimating changes in groundwater storage, uncertainties in these approaches, and comparisons of storage estimates from GRACE with those based on regional water level monitoring data and regional groundwater models. This analysis should advance applications of GRACE data in assessing changes in groundwater storage and highlight important factors to constrain uncertainties in storage estimates.