Research on the Features and Driving Factors of Shallow Groundwater Quality in Arid Areas, Northwest China

Given the increasing threat of groundwater pollution, comprehending the trends and influencing factors of groundwater quality variation is essential for effective mitigation strategies. This study addresses groundwater quality variations in the Beichuan River, a critical area in China’s arid region. Using hydrochemical analysis and multivariate statistics, we identified key factors influencing groundwater quality. Groundwater is mildly alkaline, with HCO3−-Ca as the dominant hydrochemical type. The concentrations of major ions increase during the high-flow period due to rainfall effects. The dissolution of rock salt primarily contributes to the presence of Na+ and Cl− ions. Meanwhile, the weathering of silicate and carbonate rocks is the main origin of Ca2+, Mg2+, and HCO3− ions. Additionally, the dissolution of evaporite rocks is identified as the principal source of SO42−. Human activities, particularly sewage discharge and fertilization, significantly contribute to nitrate contamination. Principal component analysis revealed that the weathering of rocks and industrial activities are the main controlling factors during the high-flow season, while the hydrochemistry of groundwater during the low-flow season is mainly influenced by the weathering of silicate rocks, evaporite rocks, and rock salt. Our findings provide a scientific basis for preventing groundwater quality deterioration and ecological environmental protection in arid regions.