Permanent scatterer InSAR reveals seasonal and long-term aquifer-system response to groundwater pumping and artificial recharge

[1] Permanent scatterer InSAR (PSInSARk) provides a new high-resolution methodology for detecting and precisely measuring long-term and seasonal aquifer-system response to pumping and recharge. In contrast to conventional InSAR, the permanent scatterer methodology utilizes coherent radar phase data from thousands of individual radar reflectors on the ground to develop displacement time series and to produce velocity field maps that depict aquifer-system response with a high degree of spatial detail. In this study, we present the first results of a prototype study in Las Vegas Valley, Nevada, that demonstrate how this methodology can be utilized in heavily pumped groundwater basins to analyze aquifer-system response to long-term and seasonal pumping. We have developed a series of velocity field maps of the valley for the 1992–1996, 1996– 2000, and 2003–2005 time periods that show that despite rising water levels associated with an artificial recharge program, long-term, residual, inelastic aquifer-system compaction (subsidence) is continuing in several parts of the valley. In other areas, however, long-term subsidence has been arrested and locally reversed. The seasonal, elastic responses to alternating pumping and recharge cycles were segregated from the long-term trends and analyzed for spatial and temporal patterns. The results show oscillations in which the maximum seasonal responses are associated with the late stages of the annual artificial recharge cycles, and that similar seasonal subsidence signals are related to summer pumping cycles. The differentiation of the seasonal response through the use of time series data further allows the estimation of elastic and inelastic skeletal storage coefficients, providing a basis for future work that could characterize the storage properties of an aquifer system with a high degree of spatial resolution.