地下水是拉萨河流域重要的饮用水源，人类活动和全球变化对区内地下水存在一定影响。为研究拉萨河流域地下水水质状况，在区内采集65组地下水样品，分析测试31项指标。运用数理统计、相关性分析、水文地球化学图示等方法，系统解析地下水化学特征及控制因素，并采用单指标最高类别法、内梅罗指数、模糊数学法和熵权水质指数（entropy weight water quality index, EWQI）进行水质综合评价。结果表明：研究区地下水呈弱碱性淡水特征，以Ca²⁺、Mg²⁺和、为优势离子，水化学类型以HCO₃-Ca和HCO₃·SO₄-Ca型为主；岩石风化作用为主导控制因素，硅酸盐岩和碳酸盐岩矿物风化溶解是区内地下水水化学成分的主要来源；EWQI和模糊数学法评价得出区内地下水质以Ⅰ类为主、水质整体偏好，单指标最高类别法判别出地下水超标组分主要为硝酸盐、氨氮、铁锰和砷，硝酸盐和氨氮主要受人类农业活动影响，局部铁锰和砷异常与原生水岩作用密切相关；对比4种典型的水质评价方法，单指标法侧重安全阈值控制，EWQI与模糊数学法更适用于多指标综合评价，方法选择需结合评价指标特征及服务功能需求。研究成果可为青藏高原典型流域地下水污染防治及饮用水安全保障提供科学依据。

Groundwater is an important drinking water source in the Lhasa River Basin, and human activities and global changes have a certain impact on groundwater in the region. To study the groundwater quality status in the Lhasa River Basin, 65 sets of groundwater samples were collected in the study area, and 31 indicators were analyzed and tested. The hydro-chemical characteristics and controlling factors of groundwater in the study area were analyzed by using methods such as mathematical statistics, correlation analysis, hydrogeochemical diagram. A comprehensive evaluation of water quality in the study area was conducted using four methods: single index highest category method, Nemerow index, fuzzy mathematics method, and entropy weight water quality index(EWQI). The results show that the overall water quality in the study area is weakly alkaline freshwater as a whole. Ca²⁺, Mg²⁺, , are the dominant ions, and the hydrochemical types are mainly HCO₃-Ca and HCO₃·SO₄ -Ca. Rock weathering, particularly the dissolution of silicate and carbonate minerals, serves as the dominant mechanism controlling hydrochemical composition. The water quality evaluation results indicate an overall preference for groundwater in the area. EWQI and fuzzy mathematics methods have evaluated that the groundwater quality in the area is mainly Class Ⅰ. The single index highest category method identifies that the main components of groundwater exceeding the standard include nitrate, ammonia nitrogen, iron manganese, and arsenic. Nitrate and ammonia nitrogen pollution likely originates from agricultural non-point sources, whereas localized Fe, Mn, and As anomalies are attributed to natural geogenic processes. Methodological comparisons demonstrate that single-factor assessment prioritizes safety thresholds, whereas EWQI and fuzzy mathematics methods better accommodate multi-indicator evaluations. Method selection should align with specific water quality parameters and functional requirements. The research results provide critical insights for groundwater pollution control and drinking water safety management in typical Tibetan Plateau watersheds.