Simulation of surface water–groundwater interaction in coal mining subsidence areas: A case study of the Kuye River Basin in China

Abstract

Coal mining subsidence (CMS) alters surface water–groundwater interactions, increasing the complexity and uncertainty of the water cycle. Here, we propose an integrated model for simulating the water system in coal mining subsidence areas (CMSAs).Using the major coal-rich sub-basins in the Yellow River Basin of China as the study area, we identified the CMSAs, established a water system model based on historical hydrological data (2005 ∼ 2020), and predicted the future evolution of the water system under the combined influences of climate, land use, and coal mining activities (2021 ∼ 2060). The results show that, by 2060, compared with the scenario without CMS, the annual surface runoff will decrease by 0.29 m³/s, while the groundwater levels in the unconfined and the confined aquifer will decline by 10.28 m and 11.64 m, respectively. These alterations derive from three synergistic mechanisms: (1) the natural hydrological cycle is disrupted through CMSAs, leading to a sustained reduction in surface runoff and seasonal river discontinuities; (2) the surface water–groundwater connectivity is enhanced via coal mining goaf and induced fractures, accelerating the groundwater loss through mine drainage; (3) the regional groundwater funnels form in CMSAs due to clustered coal extraction, leading to a significant decline in groundwater levels. This study demonstrates that CMS exerts a negative influence on surface runoff and groundwater levels, large-scale clustered mining operations serve as the primary driver of surface water–groundwater exchange in coal-rich river basins. We propose that in the context of global efforts to address climate change, the necessary efforts should be made to manage and utilize CMSAs, mitigate hydrological degradation, and ensure water security.