Ground subsidence and disaster risk induced by groundwater overexploitation: A comprehensive assessment from arid oasis regions

Water resources in arid regions are limited, with socio-economic development largely dependent on groundwater extraction, particularly in irrigated oases. Excessive groundwater use can lead to aquifer depletion and land subsidence, yet the mechanisms linking subsidence to groundwater changes across different hydrological units remain inadequately understood. This study investigates the spatiotemporal deformation characteristics in the Sangong River Watershed, China, using InSAR data from 2004 to 2021. The results indicate that subsidence primarily occurs in the upper alluvial plain oases, exhibiting cyclic patterns that correspond with agricultural activities. Subsidence has intensified in recent years, with more severe impacts observed between 2014 and 2021 compared to 2004 to 2010. Regression coefficients between groundwater levels and subsidence vary significantly, influenced by the transition from a single-layered phreatic aquifer to a multilayered phreatic-confined aquifer system. Field investigations at Liuyuhu Farm and Binghu Reservoir highlighted severe infrastructure damage caused by seasonal and differential subsidence. Overexploitation of groundwater before 2006 initiated subsidence, which worsened as cropland expanded by 32.6 % and groundwater extraction increased by 353 % from 2006 to 2014. Although government interventions from 2015 to 2021 reduced extraction rates, drought conditions from 2019 to 2021 exacerbated subsidence, resulting in a cumulative deformation volume of 5.1 x 107 m3 by 2021. The findings underscore the inadequacy of current water resources to meet agricultural demands, leading to continued extraction from static groundwater reserves, which intensifies surface subsidence. This situation necessitates urgent and more effective groundwater management strategies to mitigate further ground subsidence.