Hydrochemical Characteristics and Driving Factors of Surface Water in Nenensangcuo, Eastern Margin of Qinghai–Tibet Plateau, China

Nenensangcuo is a typical karst travertine scenic spot in the eastern margin of Qinghai−Tibet Plateau. Studying its hydrochemical evolution characteristics and driving factors is of great significance to local economic and social development and scientific management of water resources. The characteristics of hydrochemistry are analyzed by mathematical statistics, and the types of hydrochemistry are analyzed by Piper’s three-line diagram. The sources of main ions in surface water and their influencing factors are discussed by Gibbs diagram and ion correlation analysis. The pH value of water body varies from 6.6–8.2, and the TDS value varies from 210–747 mg/L. The main sources are Ca²⁺, \({\text{HCO}}_{3}^{ - }\), Mg²⁺, Cl^– and \({\text{SO}}_{4}^{{2 - }}\). The dominant cation is Ca²⁺, the dominant anion is \({\text{HCO}}_{3}^{ - }\), and the hydrochemical type is HCO₃–Ca. The hydrochemical composition is comprehensively influenced by weathering, mineral dissolution and precipitation of rocks, in which Ca²⁺ and \({\text{HCO}}_{3}^{ - }\) mainly come from weathering and dissolution of carbonate rocks.