InSAR Time-Series Analysis of Progressive Land Subsidence Caused by Groundwater Pumping in Parowan, Utah

Abstract:

Parowan Valley, Utah is an agricultural area that is experiencing significant subsidence due to extensive groundwater extraction from aquifers with compressible (clay-rich) sediments. Using a time-series Interferometric Synthetic Aperture Radar (InSAR) analysis of 140 Sentinel C-band scenes, we found that Parowan Valley experienced over 30 centimeters of ground subsidence from 2014 to 2020. Because of the high temporal sampling rate of the Sentinel-1 satellite (12-day cycle), it is possible to determine the seasonal changes of ground deformation and relate it to groundwater extraction. To better understand the relation between ground deformation and groundwater extraction in Parowan, we analyzed hydraulic head data from 20 USGS monitoring wells and built a geologic model indicating the interbedding of fine- and coarse- grained deposits in the subsurface based on 300 well logs provided by Utah Division of Water Rights. Our investigation of hydraulic head, geology, and InSAR-derived ground displacement data indicate that the most subsidence is present where there is co-occurrence of high groundwater demand and clay-rich sediments. Due to the combination of sustained depletion, strong seasonal oscillations in head, and year-to-year variability in water availability, the subsidence patterns are complex and likely have some combination of inelastic, or permanent, subsidence and elastic, or recoverable, subsidence.