Land Surface Rebound and Groundwater Temperature Fluctuations During AquiferRecovery at The Buckman Municipal Wellfield, Santa Fe New Mexico (USA)

The Buckman well field near Santa Fe, New Mexico, experienced drawdowns in excess of 180 m and inelastic subsidence over the past 35 years. Recent, increased reliance on surface water diversions has reduced pumping and resulted in water level recovery. Here, we examine both InSAR time series observations of surface deformation that can be linked to changes in hydraulic head from 1997-2018 on the ERS, ALOS and Sentinel-1 platforms, and fluctuations in groundwater temperatures during this period of rapid water level recovery. A nonlinear inversion of the surface deformation signal for a combination of pressure point source models suggests that about 1/34 of the volume lost between 1997 - 2003 was recovered between 2007 - 2010. However, the deformation signal is complex, with patterns of uplift and subsidence revealing buried structure and compartmentalization of the aquifer system. A discontinuity in the InSAR observations can be associated with lateral changes in vertical thermal gradients and water chemistry. Repeat measurements of vertical thermal gradients in monitoring wells show increased groundwater temperatures ( 0.5 °C) during the water level recovery. The increased temperatures are observed at shallower depths, and are co-located with areas of surface uplift. High correlation between surface deformation and water levels in production wells when not in use allows a first-order approximation of specific storage between 0.0004 - 0.0021 m^-1, which suggests that recent deformation is primarily elastic. Simple, one dimensional hydrothermal models of pumping, enhanced recharge and convective cooling followed by conductive recovery are qualitatively consistent with observed changes in well field temperature through time.