Seasonal subsidence and rebound in Las Vegas Valley, Nevada, observed by Synthetic Aperture Radar Interferometry

TLDR

Analyses of spatial variations in subsidence and rebound over stressed aquifer systems, linked to hydraulic‑head fluctuations, can reveal compressibility and storage properties, yet such areal stress‑strain relations are rarely used because spatial deformation data are scarce and point‑source measurements dominate. The study aims to map seasonal, recoverable aquifer deformations in Las Vegas Valley using InSAR. InSAR techniques map ground displacements at tens‑of‑meters resolution over 100‑km swaths, enabling the authors to measure small seasonal deformations in the Las Vegas Valley aquifer system. The InSAR data reveal small seasonal deformations, allow estimation of the elastic storage coefficient at multiple sites, and demonstrate the method’s potential for detailed aquifer mechanics and monitoring.

Abstract

Analyses of areal variations in the subsidence and rebound occurring over stressed aquifer systems, in conjunction with measurements of the hydraulic head fluctuations causing these displacements, can yield valuable information about the compressibility and storage properties of the aquifer system. Historically, stress‐strain relationships have been derived from paired extensometer/piezometer installations, which provide only point source data. Because of the general unavailability of spatially detailed deformation data, areal stress‐strain relations and their variability are not commonly considered in constraining conceptual and numerical models of aquifer systems. Interferometric synthetic aperture radar (InSAR) techniques can map ground displacements at a spatial scale of tens of meters over 100 km wide swaths. InSAR has been used previously to characterize larger magnitude, generally permanent aquifer system compaction and land subsidence at yearly and longer timescales, caused by sustained drawdown of groundwater levels that produces intergranular stresses consistently greater than the maximum historical stress. We present InSAR measurements of the typically small‐magnitude, generally recoverable deformations of the Las Vegas Valley aquifer system occurring at seasonal timescales. From these we derive estimates of the elastic storage coefficient for the aquifer system at several locations in Las Vegas Valley. These high‐resolution measurements offer great potential for future investigations into the mechanics of aquifer systems and the spatial heterogeneity of aquifer system structure and material properties as well as for monitoring ongoing aquifer system compaction and land subsidence.