Santa Fe, NM
January 3, 2020
The American Geophysical Union published a recent paper co-authored by Bureau Senior Geophysicist and Field Geologist Dr. Shari Kelley. The paper “Decadal-Scale Aquifer Dynamics and Structural Complexities at a Municipal Wellfield Revealed by 25 Years of InSAR and Recent Groundwater Temperature Observations” is also co-authored by New Mexico Tech (NMT) Earth and Environmental Science Professor Dr. Mark Person, former NMT student Matthew Folsom, and by University of Alaska Fairbanks Associate Professor Dr. Ronni Grapenthin. The paper examines historical surface subsidence in the Buckman wellfield induced by groundwater extraction.
The study reconstructed surface subsidence using the European Remote Sensing Satellite, Advanced Land Observing Satellite, and Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR). The history of surface deformation in the wellfield is complex; some areas experienced subsidence while some areas simultaneously experienced uplift. Repeat well water temperature measurements collected by students participating in the Summer of Applied Geophysical Experience (SAGE) field program combined with modeling helped reinforce the idea that the confined aquifer tapped by the wellfield is compartmentalized, likely due to complex subsurface stratigraphy in which the sand lenses that hold ground water are not horizontally continuous. The temperature measurements were collected from 2013-2018 when water levels recovered due to increased utilization of surface water and reduced pumping. These measurements can indicate water flow paths within the aquifer. The results of the measurments suggest that a mapped fault through the wellfield is either highly vertically permeable, allowing groundwater to migrate down through the aquifer, or dies out in the southern part of the field. The study demonstrates the importance of incorporating detailed stratigraphy and subsurface structure when modeling near-surface deformation.