锡林河上游雨季降水、河水和地下水转化关系

Relationship Between Precipitation,River Water,and Groundwater Conversion in the Upper Reaches of Xilin River During the Rainy Season

为深入理解草原内陆河流域的水文循环过程及不同水体转化机制,以锡林河流域大气降水、河水和地下水为研究对象,对其氢氧稳定同位素进行了测试及多尺度时空特征分析,探究流域不同水体间的定量转化关系.结果表明:(1)锡林河流域具有明显的内陆性半干旱气候特征,大气降水是流域河水和地下水的主要补给源,地下水和河水同时经历了不同程度的非平衡蒸发;(2)河水同位素组成在季节上表现出春秋贫化、夏季富集的特征,在空间上表现为自上游到下游逐渐升高的趋势;浅层和深层地下水δ^(18)O在生长季的波动变化基本一致,二者的主要差异发生在生长季末期,即前者趋于稳定而后者呈上升趋势,反映出深层地下水对大气降水和地表水入渗补给具有滞后响应,在空间上二者均由东南向西北逐渐贫化;(3)基于端元混合模型的估算结果可知,夏季大气降水和浅层地下水对河水的平均补给比例分别为52.69%和47.31%,说明对于内陆河流域,即使在多雨季节,浅层地下水也是河水的重要补给来源,研究旨在为半干旱典型草原内陆河流域的水资源调控和生态环境保护提供理论指导.

To deeply understand the hydrological cycle process and the transformation mechanism of different water bodies in the grassland inland river basin,the atmospheric precipitation,river water,and groundwater in the Xilin River Basin were taken as the research objects,the hydrogen and oxygen stable isotopes were analyzed,and the multi-scale spatio-temporal characteristics were analyzed to explore the quantitative transformation relationship between different water bodies in the basin.The results showed that:①the Xilin River Basin had an obvious inland semi-arid climate,the atmospheric precipitation was the main source of recharge for the river water and groundwater,and the groundwater and river water experienced different degrees of non-equilibrium evaporation at the same time.②The isotopic composition of the river water showed the characteristics of depletion in spring and autumn and enrichment in summer and showed a trend of increasing from upstream to downstream in space.The variation in δ^(18)O in shallow and deep groundwater during the growing season was basically the same,and the main difference between the two occurred at the end of the growing season,that is,the former tended to be stable,whereas the latter showed an upward trend,which reflected that the deep groundwater had a lagged response to the infiltration and recharge of atmospheric precipitation and surface water,and both of them were depleted gradually from southeast to northwest in space.③Based on the estimation results of the endmember mixing model,the average recharge ratio of atmospheric precipitation and shallow groundwater to river water in summer was 52.69% and 47.31%,respectively,indicating that shallow groundwater was an important recharge source of river water in the inland river basin even during the rainy season.The results of this study provide theoretical guidance for water resource regulation and ecological environment protection in a typical semi-arid grassland inland river basin.