Multivariate Analysis of Water Quality of the Chenqi Basin, Inner Mongolia, China

Numerous water samples are necessary to predict and assess water quality. However, if the geographical conditions surrounding mines are harsh mountainous areas, continuous or uniform sampling can be challenging, resulting in difficult sampling or data loss. In this study, statistical analysis of normalized data collected in the Chenqi Basin, including factor analysis and principal component analysis, revealed the water quality’s macro-distribution. Analytic solutions of partial differential equations of regional phreatic water quality were used to evaluate the mining and recharge–discharge of the regional phreatic aquifer. This method compensates for the disadvantage of evaluating discrete samples. Hydrogeological monitoring, pumping tests, and water quality analysis of phreatic water were carried out in the west of the Dongming open pit mine. Eight hydrogeochemical water quality variables (WQV) were selected as analysis targets. With hydrogeological generalization, regression equations of the diffusion of WQV and the seepage field were developed by a cumulative index that samples data from different orientations. One-dimensional diffusion partial differential equations of WQV, which are related to the distance and time of the seepage flow, were derived. Current and future predictions and evaluations of the phreatic water quality in the basin were made by ArcGIS based on regression and cumulative evaluation index methods. Findings revealed that the influence area of the mine would significantly expand in 10 years if current conditions continue. In addition, the diffusion speed was found to be higher in the southwestern part of the mine than in the west and northwestern parts, which is consistent with the recharge and discharge conditions of the Chenqi Basin.