oa Satellite-Based INSAR Measurements: A New Approach to Groundwater Monitoring

Throughout the western U.S., and in numerous other regions around the world, there is a growing need to monitor and regulate groundwater levels. Remotely sensed data offer spatially and temporally dense measurements over very large areas. of particular relevance to the characterization of groundwater systems is interferometric Synthetic Aperture Radar (inSAR), a remote sensing method that maps relative ground surface deformation. We present a methodology, using an advanced inSAR processing technique known as Small Baseline Subset Analysis (SBAS), that allows us to observe seasonal deformation and relate it to changes in the thickness of the confined aquifer due to recharge and withdrawal of groundwater.<br>We have applied our methodology in the San Luis Valley (SLV), an 8000 km2 region in southern Colorado that is home to a thriving agricultural economy. the state has developed a hydrogeologic database and a groundwater flow model in order to quantitatively study possible management schemes for water resources in the SLV. Because well-sampled hydrographs, accurate lithologic logs and high quality aquifer tests are scarce, the model has not yet been able to characterize the spatially heterogeneous, time-varying behavior of the groundwater system. the more complete coverage offered by inSAR allows us to augment these sparse measurements. We infer hydraulic head change in the confined aquifer system by combining inSAR measurements with aquifer test data and lithologic logs. Conversely, where well-sampled hydrographs exist we use inSAR data in conjunction with the thickness of the producing zone to estimate the specific storage of the producing sediments. We propose a framework to combine all existing data together with the inSAR deformation estimates in order to improve the groundwater flow model. Ultimately all data types can be incorporated within this mathematical framework to better inform the decision-making process for groundwater management.