在淡水资源短缺的苦咸水地区查明地表水与地下水转换关系，对于揭示区域水文循环机制，促进苦咸水资源的合理利用具有重要意义。以宁夏苦水河流域为研究对象，采用氢氧稳定同位素技术，结合野外调查、统计分析与水化学分析法，分析了地表水和地下水的水化学与氢氧稳定同位素时空分布特征，系统揭示了流域内地表水与地下水转化关系的时空变化规律。结果表明：（1） 苦水河流域地表水与上游、中游地下水的水化学类型均以SO₄·Cl-Na·Mg为主，地表水的水化学形成作用为蒸发浓缩。下游地下水的水化学类型转变为混合型，水化学形成作用转变为受岩石风化控制。（2） 大气降水对丰水期地表水与地下水的补给作用显著，对枯水期补给作用有限。流域上游、中游受气候、地形、水文地质条件控制，地表水与地下水转关系在不同时期不同河段表现出显著的差异性与复杂性。下游区域受引黄灌溉的影响作用明显。（3） 枯水期地表水与地下水水力联系密切的区域分布于中游、下游，水循环模式均为地下水补给地表水，补给比例分别为51.8%、57.8%。丰水期干流地表水与上、中游地下水水力联系微弱，下游地表水补给地下水，补给比例为38.8%，同时下游渠水对地表水有一定的补给作用，补给比例为29.8%。

Brackish water is widely distributed in the arid and semiarid areas of northwest China. Understanding the relationship between surface water and groundwater transformation in brackish water areas is significant for promoting the rational development of brackish water resources. Taking the Kushui River Basin in Ningxia, China as the research object, this study analyzes the spatial and temporal distribution characteristics of hydrochemistry and hydrogen-oxygen stable isotopes of surface water and groundwater using hydrogen-oxygen stable isotope technology combined with field investigation, statistical analysis, and hydrochemical analysis. The spatial and temporal variations in the conversion relationship between surface water and groundwater in the basin were systematically revealed. The following results were observed: (1) SO₄·Cl-Na·Mg is the main hydrochemical type of surface water and upstream and midstream groundwater in the Kushui River Basin. The hydrochemical formation of surface water was evaporation concentration, and the hydrochemical type of downstream groundwater was transformed into a mixed type, which was controlled by rock weathering. (2) Atmospheric precipitation has a significant recharge effect on surface water and groundwater in the wet season and has a limited recharge effect in the dry season. Climate, topography, and hydrogeological conditions controlled the upper and middle reaches of the river basin, and the relationship between surface water and groundwater showed significant differences and complexity in different river reaches and periods. The irrigation of the Yellow River obviously affected the downstream. (3) In the dry season, the areas with close hydraulic connection between surface water and groundwater are distributed in the middle and lower reaches. The water cycle mode was referred to as groundwater recharge surface water, with recharge ratios of 51.8% and 57.8%, respectively. In the wet season, the hydraulic connection between the surface water of the mainstream and the groundwater in the upper and middle reaches is weak. The downstream surface water supplied the groundwater, with a recharge ratio of 38.8%. At the same time, the downstream canal water supplied the surface water to a certain extent, with a recharge ratio of 29.8%.