Estimation of annual groundwater changes from InSAR-derived land subsidence

Understanding the extent and quantity of groundwater drawdown is critical for developing a mitigation strategy for water management. This study illustrates that the data-driven model can be used for the spatial estimation of groundwater drawdown using interferometric synthetic aperture radar (InSAR)-based deformation data. Here, InSAR derived from Sentinel-1 imagery is used to estimate surface deformations in the Choshui river alluvial fan, Taiwan, between 2016 and 2018. Spatial regression (SR) is applied to estimate the annual groundwater drawdown with a calculated R-square of 0.96, which is shown to be superior to a nonspatial model. This study demonstrates the potential of the satellite-based groundwater drawdown map prediction using InSAR-derived land deformation. In predication, the SR model can reliably catch the patterns of annual predicted drawdown without requiring detailed groundwater observations.