title: Assessing Groundwater Depletion and Dynamics Using GRACE and InSAR: Potential and Limitations.
abstract: In the last decade, remote sensing of the temporal variation of ground level and gravity has improved our understanding of groundwater dynamics and storage. Mass changes are measured by GRACE (Gravity Recovery and Climate Experiment) satellites, whereas ground deformation is measured by processing synthetic aperture radar satellites data using the InSAR (Interferometry of Synthetic Aperture Radar) techniques. Both methods are complementary and offer different sensitivities to aquifer system processes. GRACE is sensitive to mass changes over large spatial scales (more than 100,000 km2). As such, it fails in providing groundwater storage change estimates at local or regional scales relevant to most aquifer systems, and at which most groundwater management schemes are applied. However, InSAR measures ground displacement due to aquifer response to fluid-pressure changes. InSAR applications to groundwater depletion assessments are limited to aquifer systems susceptible to measurable deformation. Furthermore, the inversion of InSAR-derived displacement maps into volume of depleted groundwater storage (both reversible and largely irreversible) is confounded by vertical and horizontal variability of sediment compressibility. During the last decade, both techniques have shown increasing interest in the scientific community to complement available in situ observations where they are insufficient. In this review, we present the theoretical and conceptual bases of each method, and present idealized scenarios to highlight the potential benefits and challenges of combining these techniques to remotely assess groundwater storage changes and other aspects of the dynamics of aquifer systems.
authors: Pascal
authors: P
authors: Castellazzi
authors: Institut national de la recherche scientifique, Centre Eau, Terre et Environnement, Université du Québec, 490 rue de la Couronne, Québec, QC, Canada G1K 9A9.
authors: Richard
authors: R
authors: Martel
authors: United States Geological Survey, Water Science Field Team - West, 5957 Lakeside Boulevard, Indianapolis, IN 46278-0000.
authors: Devin L
authors: DL
authors: Galloway
authors: Géosciences Rennes, UMR CNRS 6118. Université Rennes 1, Campus Beaulieu. 35042 Rennes Cedex, France.
authors: Laurent
authors: L
authors: Longuevergne
authors: Geological Survey of Canada, Natural Resources Canada, 490, rue de la Couronne, Quebec, QC, Canada G1K 9A9.
authors: Alfonso
authors: A
authors: Rivera
mesh_terms: D002980:Climate; D006112:Gravitation; D060587:Groundwater