Combining InSAR and Hydraulic Head Measurements to Estimate Aquifer Parameters and Storage Variations of Confined Aquifer System in Cangzhou, North China Plain

Abstract

AbstractGroundwater storage (GWS) depletion and land subsidence caused by groundwater overexploitation threaten water supply and infrastructure security in the North China Plain. However, the aquifer system responses to groundwater changes are poorly understood in this region, although it is extremely important for groundwater management and land subsidence control. In this study, aquifer parameters and GWS variations of the confined aquifer system in central Cangzhou are quantified by using Interferometric Synthetic Aperture Radar (InSAR) and hydraulic head measurements. We apply the multitemporal InSAR method to detect land deformation time series with Envisat Advanced Synthetic Aperture Radar (ASAR) data from 2003 to 2010. Seasonal signals in land deformation and head data are isolated by multichannel singular spectrum analysis to derive the elastic skeletal storativity (Ske). The results reveal a spatially heterogeneous Ske pattern with values ranging from 1.7 × 10−4 to 4.4 × 10−3 that agree well with those derived from pumping tests. An abnormal Skezone is found in the land uplift zone, and a gradual increase of Ske is revealed in the eastern coastal plain, which are likely attributed to the hydrological properties in the aquifer systems. Additionally, we characterize spatiotemporal variations in the total GWS, recoverable GWS, and irreversible GWS. The annual depletion rates of recoverable GWS and irreversible GWS are −0.52 ± 1.27 × 107 and −7.68 ± 2.68 × 107 m3/year, accounting for 6.4% and 93.6% of annual total GWS depletion, respectively, suggesting that previous groundwater pumping practices are unsustainable in this region. Finally, we find a 1‐year lag of the IGWS depletion variations behind the head changes due to low vertical hydraulic conductivities in aquitards.