EBTAG Annual Workshop and Field Trip
October 12-13, 2017

¹Earth and Environmental Science Department, New Mexico Institute of Mining and Technology, Socorro, NM, 87801, shari.kelley@nmt.edu

²New Mexico Bureau of Geology and Mineral Resources, New Mexico Tech, Socorro, NM, 87801

The Buckman well field has provided municipal water to Santa Fe for 35 years, and has a history of substantial (> 100 m) drawdowns and inelastic subsidence. Recent changes to the design and operation of the well field have resulted in significant water level recovery. Here we examine both InSAR observations of surface deformation that can be linked to changes in hydraulic head, and increases in groundwater temperatures during this period of rapid water level recovery. A non-linear inversion of the surface deformation signal for parameters of a combination of pressure point source models suggests that about 1/36 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 is associated with lateral changes in water chemistry and vertical thermal gradients (46 to 79°C/km over a distance of 300 m). Repeat measurements of thermal profiles in monitoring wells showed little to no change between 2013 and 2014. However, in 2015, two of the wells began flowing and temperatures at the bottom (<100 m) rose by 0.33–0.37 °C (±0.01 °C) between 2014 and 2017, with the most dramatic change occurring from 2014 to 2016. Simple, one-dimensional hydrothermal models support the hypothesis that groundwater development resulted in convective cooling 1997–2003, followed by conductive warming 2003–2017. These increased temperatures are co-located with the areas of observed surface uplift. High correlation between surface deformation and water levels in production wells when not in use allows a first-order approximation of elastic storage parameters between 0.0004–0.0021, which suggests that the surface deformation 2007–2010 was primarily elastic and some storage capacity may have been lost during prior periods of production.

Temperature-depth plots for deep (SF4a) and shallow (SF4b) monitoring piezometers in the Buckman well field measured between 2013 and 2017 by Summer of Applied Geophysical Experience (SAGE) students.