基于水化学及径流组成的中国西北内陆河流域水资源风险评估

Assessing water resource risks in inland river basins of Northwest China from water chemistry and runoff

水资源作为西北内陆区重要的战略性资源,关系着区域经济社会可持续发展。内陆河作为区域重要的水资源组成部分对全球气候变化响应显著。本文选取祁连山、天山、昆仑山地区典型的内陆河流域,基于长期径流监测,以及降水、融水、河水、地下水等多水体水化学、同位素分析数据,分析了区域径流组成特征及其与主要环境要素的相互关系,评估了其水资源风险。结果表明:(1)除石羊河外,20世纪70年代以来研究区大部分河流的年径流量呈现上升趋势;(2)研究区各水体大部分为碱性,各水体主导阴阳离子为HCO3-和Ca^(2+)和Na^(+),水化学类型多为HCO_(3)--Ca^(2+)型,且受岩石风化控制影响大;河水TDS呈现相似的季节变化趋势(夏秋低冬春高),而各离子的季节差异显著;(3)除呼图壁河外,区域河水的δ^(18)O呈现出夏秋低冬春高的季节变化特征;(4)研究区地下水、降水和冰川/雪融水对区域径流的年平均贡献分别为42.6%、34.4%和23.0%,区域径流组成存在空间异质性;(5)气温变化会增加阿克苏河、和田河和石羊河发生径流变化的风险,而降水波动可能对提孜那甫河流域和疏勒河流域的径流过程构成潜在的风险,和田河存在潜在水质风险。本文研究结果对于区域水资源可持续利用具有重要意义。

As an important strategic resource in the arid inland region of Northwest China,water resources are related to the sustainable development of the regional economy and society.As important regional water resources,inland river basins are highly sensitive to global climate change.In this study,we studied the typical inland river basins in the Qilian Mountains,Tianshan Mountains,and Kunlun Mountains.The regional runoff composition and its relationships with the main environmental factors were analyzed based on long-term runoff monitoring and water chemical isotope analysis data of precipitation,meltwater,river water,groundwater,and other water bodies.The results showed that:(1)Except for the Shiyang River,the annual runoff of most rivers in the study area showed an upward trend in recent decades;(2)Most of the water bodies in the study area were alkaline,and the dominant anion and cation of each water body were HCO_(3)^(-),and Ca^(2+)and Na^(+),respectively.The hydrochemical type was mostly HCO_(3)--Ca^(2+),which is strongly affected by rock weathering.The TDS of river water showed a similar seasonal trend,being low in summer and autumn,but high in winter and spring.Meanwhile,the seasonal differences of each ion are relatively prominent.(3)Except for the Hutubi River,the variation trend for δ^(18)O was relatively consistent,showing the seasonal variation of low in summer and autumn while high in winter and spring throughout the year.(4)The average annual contributions of groundwater,precipitation,and glacier/snow meltwater to regional streamflow in the study area were 42.6%,34.4%,and 23.0%,respectively,with spatial heterogeneity in regional runoff composition.(5)In the context of climate change,regional temperature variability will increase the risk of runoff changes in the Aksu,Hotan,and Shiyang rivers,whereas fluctuations in precipitation may pose potential risks to runoff processes in the Tizinafu and Shule river basins,and there are potential water quality risks in the Hotan River.The results of this study have strong implications for the sustainable use of regional water resources.