Seasonal subsidence and rebound in Las Vegas Valley, Nevada, observed by synthetic aperture radar interferometry

Analyses of areal variations in the subsidence and rebound occurring over s tressed aquifer systems, in conjunction with measurements of the hydraulic head fluctuations causing these displacements, can yield valuable informati on about the compressibility and storage properties of the aquifer system. Historically, stress-strain relationships have been derived from paired ext ensometer/piezometer installations, which provide only point source data. B ecause of the general unavailability of spatially detailed deformation data , areal stress-strain relations and their variability are not commonly cons idered in constraining conceptual and numerical models of aquifer systems. Interferometric synthetic aperture radar (InSAR) techniques can map ground displacements at a spatial scale of tens of meters over 100 km wide swaths. InSAR has been used previously to characterize larger magnitude, generally permanent aquifer system compaction and land subsidence at yearly and long er timescales, caused by sustained drawdown of groundwater levels that prod uces intergranular stresses consistently greater than the maximum historica l stress. We present InSAR measurements of the typically small-magnitude, g enerally recoverable deformations of the Las Vegas Valley aquifer system oc curring at seasonal timescales. From these we derive estimates of the elast ic storage coefficient for the aquifer system at several locations in Las V egas Valley. These high-resolution measurements offer great potential for f uture investigations into the mechanics of aquifer systems and the spatial heterogeneity of aquifer system structure and material properties as well a s for monitoring ongoing aquifer system compaction and land subsidence.