ESTIMATING SEASONAL GROUNDWATER PUMPING RATE USING InSAR DERIVED LAND DEFORMATION

Periodic interferometric synthetic aperture radar (InSAR) measurements can detect sub-cm scale ground displacements over large areas. Hence, it has been widely used in investigating the character and future trends of ground-deforming natural hazards. Over the last decade the technique has yielded valuable information for hydrogeological applications, such as mapping, monitoring and simulating groundwater flow, aquifer-system compaction and land subsidence. In areas with significant groundwater pumping, the InSAR signal records changes in land deformation due to periodic aquifer-system compaction and rebound, caused by seasonal changes in pumping. Therefore, InSAR measurements are a potentially valuable source of information to infer groundwater pumping rates over large areas. Here, we present preliminary results of a study aimed at estimating groundwater pumping rates using space-borne InSAR data. Our approach quantitatively links land deformation, subsurface water pressures, and groundwater pumping using subsurface compaction and groundwater flow models. Inverse methods are then used to infer seasonal groundwater pumping rates using InSAR and hydraulic head measurements. Two case studies from the Netherlands illustrate the potential of the methodology.