关键词:
Subsidence
InSAR
Low permeability media
Groundwater modeling
USA
摘要:
As groundwater depletion threatens future water availability in many regions of the world, improved monitoring is crucial. Interferometric synthetic aperture radar (InSAR) provides valuable deformation data that can be related to changes in groundwater storage, but interpreting these deformation data is challenging due to the delayed response of deformation to changes in the aquifer. Many studies have considered the delayed deformation induced by long-term depletion of groundwater, and found that permanent deformation can continue for decades after depletion has stopped. However, there have been relatively few studies that consider the delay in deformation in response to elastic, seasonal changes in aquifer groundwater levels, and an absence of studies that performed a formal modeling analysis to quantify the relative significance of various drivers of this delay. Recent studies leveraging seasonal InSAR-derived deformation data to estimate aquifer recharge pathways have highlighted the need to understand how quickly deformation responds to groundwater storage changes at the seasonal time scale. In this study, this analysis is conducted, and the findings demonstrate that under elastic conditions, seasonal delays can range from 0 to 60 days depending on the vertical hydraulic conductivity, fine-grained layer thickness, and fraction of the aquifer that is composed of coarse-grained material. Seasonal delays from field data are also explored in two regions of the western United States: the San Luis Valley, Colorado, and Central Valley, California. The seasonal delays in each of these areas were found to fall within the bounds determined in the modeling approach.