Hydrodynamic Groundwater Modeling and Hydrochemical Conceptualization of the Closure Mining Area of the WuMa River Watershed of China

Lei Yang; Lang Liu; Yuan Liu; Guangping Chen; Liying Liang

doi:10.1021/acsomega.3c05631

Hydrodynamic Groundwater Modeling and Hydrochemical Conceptualization of the Closure Mining Area of the WuMa River Watershed of China

ACS Omega. 2023 Dec 27;9(1):520-537. doi: 10.1021/acsomega.3c05631. eCollection 2024 Jan 9.

Authors

Lei Yang¹, Lang Liu^{2

3}, Yuan Liu⁴, Guangping Chen⁵, Liying Liang^{2

6

3}

Affiliations

¹ School of Geosciences and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China.
² School of Materials and Environment, Guangxi Minzu university, No. 188, University East Road, Nanning 530000, China.
³ Guangxi Colleges and Universities Key Laboratory of Environmental-friendly Materials and New Technology for Carbon Neutralization, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, School of Materials and Environment, Guangxi Minzu University, Nanning 530105, China.
⁴ Guizhou Environment and Engineering Appraisal Center, Guiyang 550002, Guizhou, China.
⁵ Guizhou ZhongGui Environmental Technology Co., Ltd., Guiyang 550008, China.
⁶ Guangxi Chemical Research Institute Limited Company, Nanning 530000, China.

Abstract

The WuMa River (WMR) watershed is located in Renhuai City, Guizhou Province of China, which is a first-class tributary of the Chishui River. The geochemical investigation mainly included the determination of groundwater pH, total hardness, total dissolution solid, major cationic and anionic, and the geochemical groundwater modeling. The principal component analysis (PCA) and Gibbs model were used to analyze the pollution type and geochemical composition. The geochemical investigation results show that the cations of groundwater are dominated by Ca²⁺ and the anions are dominated by HCO₃^-; therefore, two main hydrochemical types in the study area are identified as Ca²⁺-Mg²⁺-HCO₃^- and Ca²⁺-Mg²⁺-SO₄^2-. The chemical composition of groundwater in this area is mainly controlled by weathering of the carbonate rocks. The ion concentration of groundwater in the study area exhibited significant spatial variability between dry and wet seasons, while temporal changes of cationic and anionic concentrations exhibited irregularities. In PCA and FA analysis, PC1, PC2, and PC3 were extracted, which could explain 51.92, 26.98, and 12.61% of the total information, respectively. F1 explained 67.44% of the total variance, among which Ca²⁺, Mg²⁺, K⁺, SO₄^2-, and Cl^- contributed the most among the factors and were the main factors controlling the chemical composition of groundwater. The relative error between the measured water level and the simulated water level is less than 2%, which meets the requirements of simulation accuracy. During the simulation period of the model, a total recharge of 339.05 × 10⁴ m³ was observed in the simulated area, primarily attributed to infiltration from rainfall. The total excretion amounted to 330.78 × 10⁴ m³, primarily through evaporation, with a minor amount of lateral outflow. The migration pathway of pollutants in groundwater primarily follows the direction of groundwater flow while diffusing vertically. The migration range of the pollutant is in accordance with the direction of groundwater flow and extends along the larger hydraulic gradient, demonstrating consistency. The findings of this study serve as a reminder that the closure of coal mines can constitute a significant source of water pollution. Simultaneously, they offer empirical data and theoretical references for the simulation and prediction of groundwater contamination in enclosed coal mines.