Modeling elastic and inelastic pumping-induced deformation with incomplete water level records in Parowan Valley, Utah

Groundwater extraction causes significant land subsidence in many parts of the world with compressible sediments. InSAR data have been used to estimate the magnitude of this subsidence, and derive hydrologic and geomechanical properties in these areas. In spite of recent advances in InSAR processing methods, several challenges remain in relating surface deformation to hydrologic systems. The relationship between deformation and groundwater levels is non-linear, and existing groundwater level data are often sparsely sampled, so that it is challenging to relate them to InSAR-derived deformation. In addition, historical InSAR datasets are sparsely sampled in time, leaving many gaps in existing deformation estimates. In this study, we present an approach to improve the temporal density of groundwater level and deformation estimates. The study area for this demonstration is Parowan Valley, Utah, a region dependent on groundwater for agricultural use that has seen significant declines in head over the past 70 years. In our approach, we use Theis curves to interpolate seasonal fluctuations in head, and a subsidence model to extend deformation estimates. We find that with this approach, we are able to closely match long-term and seasonal estimates of deformation, estimate seasonal fluctuations in head, and characterize the elastic and inelastic response to changes in head.

Automated summary

Groundwater extraction leads to significant land subsidence, which can be estimated using InSAR data to derive hydrologic and geomechanical properties. Challenges remain in relating surface deformation to hydrologic systems due to the non-linear relationship between deformation and groundwater levels, as well as sparsely sampled data.