Can the anisotropic hydraulic conductivity of an aquifer be determined using surface displacement data? A case study

Abstract

Due to geological features such as fractures, some aquifers demonstrate strongly anisotropic hydraulic behavior. The goal of this study is to use a poroelastic model to calculate surface displacements given known pumping rates to predict the potential utility of Interferometric Synthetic Aperture Radar (InSAR) data for inferring information about anisotropic hydraulic conductivity (AHC) in aquifer systems. To this end, we develop a three-dimensional anisotropic poroelastic model mimicking the main features of the 1994 Anderson Junction aquifer test in southwestern Utah with a 24 to 1 ratio of hydraulic conductivity along the principal axes, previously estimated in the literature using traditional well observation techniques. Under suitable model assumptions, our results show that anisotropy in the hydraulic problem leads to a distinctive elliptical surface displacement pattern centered around the pumping well that could be detected with InSAR. We interpret these results in the context of InSAR acquisition constraints and provide guidelines for designing future pumping tests so that InSAR data can be used to its full potential for improving the characterization of aquifers with anisotropic hydraulic behavior.