After mine closure, large-scale polluted groundwater bodies develop in the goafs, posing severe threats to regional karst aquifers. This study systematically analyzed contamination mechanisms in closed goaf, and proposed prioritizing the determination of mining-induced roof or floor rock stratum failure zone heights during risk assessment, as these fractures serve as primary contaminant migration pathways. By integrating pollution pathways and aquifer properties, a comprehensive risk assessment indicator system was established. This indicator system, designated as HDCFKTPG, comprised eight indices that incorporated the unique geological features of the karst region. The random forest algorithm was applied to objectively weight evaluation indicators, enabling the development of a multifactorial model. This model demonstrated that karst groundwater contamination in closed goaf was governed by interconnected factors with highly complex genetic mechanisms. Based on this framework, an integrated GIS and database system for karst groundwater contamination risk assessment was developed, embedding mathematical models and five functional modules: file management, indicator quantification, weight calculation, risk evaluation, and spatial visualization. The software system enables precise and efficient assessment of groundwater contamination risk, and it has been successfully applied and validated in five closed goafs across Southwest China, demonstrating high accuracy and practical utility.
Li et al. (Mon,) studied this question.