The Fengfeng mining area is in the transition zone between the North China Plain and the Taihang Mountains, and groundwater is the main source of water supply in the district. Under the combined influence of human activities and natural geological conditions, the quality of different types of groundwater varies greatly, posing a potential threat to the safety of drinking water. In this study, hydrogeochemical processes in different types of groundwater were analyzed using multivariate statistical analysis methods with ion–ratio relationships, and a groundwater quality and health risk assessment model was developed. The research findings show that the main chemical components and TDS in the groundwater have obvious spatial distribution characteristics, i.e., the content of deep karst water (DKW) in the west is significantly lower than that of shallow pore water (SPW) in the east, and the hydrochemical type has changed from HCO₃–Ca to SO₄–Ca. The chemical components of SPW and DKW are mainly derived from silicates and carbonates, accompanied by weathering dissolution of sulphidic minerals, especially SPW. The chemical components of the groundwater was also influenced by the cation exchange reaction and human activities. The quality of the SPW was significantly worse than that of the DKW, and the nitrates in SPW carry a high non-carcinogenic risk, especially to children. The shallow pore water is not suitable for drinking water. This study can provide guidance on the safety of drinking water in the Fengfeng coal mining area and other areas with intensive industrial, mining, and agricultural activities.

The serious shortages and destruction of groundwater resources caused by coal mining, especially group mining, is a major hurdle for the sustainable development of the mining economy, resource management, and preserving the environment that urgently needs to be addressed. Large efforts have been made to protect the groundwater resources affected by coal mining but they have had little effect. The difficulty and uncertainty in investigating the structural changes in roof strata and the relationship between the roof rock fissure formation rate and hydraulic conductivity are the main obstacles hindering the investigation, assessment and management of groundwater resources in roof strata. In this study, we tackled this problem by performing water injection tests in ground surface boreholes and underground boreholes in the roof strata, and pumping tests in wells over the goaf. Clear differences in hydraulic conductivity changes in the collapsed roof strata were observed. These observations provide valuable information on changes in groundwater flow and the distribution of collapsed and fissured zones. The pumping tests also revealed an increase in hydraulic conductivity in the subsidence basin of Quaternary deposits over the goaf. This increased hydraulic conductivity is useful for the assessment of groundwater resources and the prediction of single-well water yields.