西北内陆河山区流域水文内循环过程及机理研究

The mountainous area is the water source formation and supply area of the whole inland river basin in northwest China, and is also the main source water for the continuous operation of the oasis economic system and ecosystem. There is not much concern about the water circulation process and mechanism of different hydrological units in mountainous areas such as snow and ice, cold desert, forest and grassland, and the water vapor exchange between different hydrological units in the basin and that between basin and the outside. We will select the Aksu River and Shule River Basin, which have better observation basis, as study area. Through the enhancing runoff zone experiment on different land cover, improving the algorithms of remote sensing inversion and ground verification on land surface evapotranspiration on different land cover, we can obtain the relationship between each component of water balance. Based on the study, we will analyze the mechanism of water vapor transfer and exchange of different land cover in the watershed by isotope tracing on the water vapor flux of vegetation water, soil moisture and atmospheric moisture, and analyzing the water vapor flux from reanalysis data. Based on coupling model of regional climate model and land surface process model, the internal mechanism of moisture transfer and exchange process of different land cover and atmosphere and the internal mechanism of water cycle in the basin are studies , and the effect of different land cover in mountain hydrological process is systematically analyzed and the potential impact of land cover change on runoff is projected.

山区是西北内陆河流域的水源形成和供给区,也是维系整个流域绿洲经济系统和生态系统持续运转的主要水源和水量中枢。目前针对山区冰雪、寒漠、森林、草地等不同水文单元的水分来源、水分在不同水文单元间以及流域内与外部的相互交换过程等水循环过程和机理还关注不多。本项目拟选择具有较好观测基础的阿克苏河和疏勒河山区流域，通过对不同下垫面的径流小区观测试验，不同下垫面蒸散发的遥感反演和地面验证，确定不同下垫面水量平衡各要素的定量关系；在此基础上，通过植被水分、土壤水分和大气水分的同位素示踪与解析，结合再分析资料的水汽通量数据，分析流域不同下垫面水分传输和交换的关联机制；以区域气候模式与陆面过程模式的耦合模型为手段，研究不同下垫面与大气的水分传输和交换过程及流域内水分循环的内在机理，从而系统分析不同下垫面在山区水文过程的作用及其变化对出山径流的影响。

围绕项目任务书中的研究目标，在降水和蒸散发等水循环要素遥感反演模型改进、水文模型优化与改进、基于同位素和再分析资料的水汽来源分析等方面均取得一定进展,初步确定了祁连山-河西走廊间水汽内循环的重要作用，识别了水汽水平方向交换的2个重要通道，完成了项目预定目标。项目主要进展包括：（1）观测和遥感数据结合，对内陆河流域降水和蒸发等关键水循环要素进行了定量估算，揭示了其海拔效应、局地和区域差异；通过观测试验，获取了高寒区气象水文及活动层等水热参数,揭示了降水-土壤水-活动层地下水-河道径流转化机制。（2）综合应用数字模拟法、同位素水化学示踪法及水文模型，对疏勒河流域上游不同河段径流组成进行了定量分割，为流域水文过程模拟提供了主要参数；利用同位素方法系统分析了内陆河流域水汽内循环特征，发现在上游生长季降水有近一半来源于当地植物蒸腾作用产生的水汽，在中游人工绿洲和荒漠绿洲过渡带的降水有近一半是由内循环水汽贡献，在下游地区只有不到四分之一的降水是由内循环水汽供给。（3）基于再分析资料系统分析了祁连山-河西走廊区水汽来源及变化特征，识别了2个从河西地区向祁连山区的水汽输送通道，初步验证了我们对内循环过程的猜想。（4）对内陆河流域冰冻圈这一特殊水文要素的变化及其水文影响进行了多尺度研究，对冰冻圈稳定性、未来水文影响进行了系统影响；通过对内陆河流域水文内循环机制及内循环在流域水文作用的研究，在系统总结国内外已有科学认识的基础上，在国际上率先构建了“冰冻圈水文学”。