Assessment of Mining-Induced Disturbance to Overlying Thermal Aquifers Based on Fuzzy Variable Set Theory: A Case Study of Tongzhe Coalfield in China

While traditional mine hydrogeology focuses on preventing water inrush to protect underground workings, this study establishes a novel evaluation framework aimed at protecting valuable, high-temperature geothermal water resources during deep coal extraction in coal–water dual-resource mines. We selected seven key indicator factors to quantify the disturbance intensity of mining to the overlying geothermal reservoir aquifer, and applied fuzzy variable set theory to evaluate the disturbance level and delineate disturbance zones to investigate the Tongzhe Coalfield area in the eastern Henan Plain of China. The results show that zones of stronger disturbance associated with the extraction of the main coal seam are concentrated in the northern, northeastern, and southwestern parts of the study area. Area statistics indicate that high disturbance zones account for 5.0% of the study area, relatively high disturbance zones for 30.6%, moderate disturbance zones for 32.6%, relatively low disturbance zones for 22.1%, and low disturbance zones for 9.7%. In total, zones at moderate disturbance or above represent 68.2%, suggesting that appropriate mining methods are required during extraction of the main coal seam to mitigate mining induced disturbance to the roof geothermal aquifer. These results provide a scientific basis for selecting mining practices that protect water resources in coal–water dual-resource mining areas.