气候变化驱动下雅鲁藏布江冰川冻土植被协同变化及其径流效应

With abundant water resources and great hydro-power capacity, the Yarlung Zangbo River has strategic importance for both China and neighboring countries. The hydrological processes in the basin are highly affected by the changes in cryosphere and land surface conditions. However, due to the data scarcity and the limitations in modeling, our understanding in the covariations among glacier, frozen soil and vegetation (3 factors) under the climate change and their influences on streamflow is still restricted, and the processes are not well quantified. To fill the knowledge gap, this project intends to: (1) establish a comprehensive observation network that includes meteorology, glacier, frozen soil, vegetation, and hydrology observations based on the existing observation stations in and around the Yarlung Zangbo River Basin that belong to the Institute of Tibetan Plateau Research, Chinese Academic Sciences, and build up much-needed basic datasets; 2) investigate the characteristics of the changes in climate, glacier, frozen soil, vegetation, and streamflow, as well as the covariations of the frozen soil-vegetation and glacier-vegetation, to lay a solid foundation for the further study of the impacts of the covariations among the 3 factors on streamflow; 3) validate physically-based, distributed hydrological models that incorporate glacier, frozen soil, and vegetation processes, to quantify the covariations among glacier, frozen soil and vegetation and their influences on streamflow, as well as the uncertainties through dual model simulations and comparisons. This project would improve the overall abilities in observation and modeling, and the understanding of the hydrological processes in the Yarlung Zangbo River Basin. Furthermore, the project could provide theoretical guide and technical support for the integrated water resources management, ecosystem conservation and development in the basin.

雅鲁藏布江水能水资源丰富，对我国及周边国家都具有重要战略意义。其水文过程受冰冻圈和地表环境变化影响显著。然而受观测资料和模型限制，气候变化驱动下雅鲁藏布江流域冰川、冻土和植被协同变化及其径流效应，仍没有得到机理上解释和定量回答。因此，针对科学需求，本项目拟开展:(1)依托中科院综合野外台站，加强和完善气象、冰川、冻土、植被和径流观测，构建流域地面综合观测网络，生成基础资料数据集；(2)基于数据集，分析气候、冰川、冻土、植被和径流各因子的变化，进而解析冻土-植被和冰川-植被的协同变化规律，为冰川-冻土-植被的径流效应研究奠定基础；(3)验证包含冰川冻土植被描述的陆面水文模型，通过模拟对比试验，定量解析冰川冻土植被协同变化的径流效应，并开展不确定性分析。项目的实施将提升雅鲁藏布江流域综合观测和模拟水平，增强对流域水文物理机制的理解，为该流域综合水资源管理、生态环境保护和发展提供科技支撑。

雅鲁藏布江（简称雅江）水能水资源丰富，对我国及周边国家都具有重要战略意义，其水文过程受冰冻圈和地表环境变化影响显著。受限于环境条件和稀缺的实地观测资料，该流域的降水、冰川、冻土、积雪和植被的变化在很大程度上仍然未知，因此无法准确评估气候变化驱动下的冰川-冻土-植被协同变化及其径流效应。. 为填补这一空白，本项目在全流域尺度建立了一个大规模的多圈层水文观测网络（包括水文气象、冰川、冻土和植被等观测），为量化气候—冰冻圈—植被变化下的径流过程提供了观测基础，主要包括：12个带有自动雨雪计和温度探头的气温和降水观测点；9个包含四层观测（10/40/80/120cm）的土壤湿度/温度观测点，覆盖高寒草甸、草原、灌木和森林；34套用于监测海拔4500-5200m之间的冻土温度探头，以及用于监测雪格拉山（5278m）和马攸木拉山（5256m）的冻土水热传输过程观测系统；5套雷达水位计观测，结合断面、河宽等测量补充缺测断面的径流信息；利用差分GPS对纳木那尼进行高精度冰川边界和冰面高程观测。在建立以上观测网的基础上，进一步收集和制作了多套基础数据，包括：气象驱动数据（主要是降水）、冰川数据集、土壤-植被基础数据集等。.在此基础上，进一步探讨了气候-冻土-植被的协同变化效应。利用SHAW模型揭示了流域植被变化对浅层土壤冻融过程的影响，基于LPJ模型揭示了流域尺度冻土退化对植被的影响以及植被变化对流域水循环的影响。进而结合分布式冰冻圈水文模型WEB-DHM和VIC-Glacier，基于融合了多源降水（包括200多个水利部降水观测点）的气象驱动数据，开展了冰川冻土植被协同变化的径流效应解析。研究表明，1981-2016年间，降雨、融雪、冰川融化和地下水补给分别占奴下以上流域总径流的65.9%、21%、9.2%和3.95%。. 随着该项目建立的多圈层水文观测平台的持续运行，将逐步对更多的（非涉密）实测数据进行质量控制和归档，然后在国家青藏高原数据中心发布(http://data.tpdc.ac.cn)。这将有助于科学家和社会更好地了解雅江流域的圈层相互作用（大气圈-生物圈-冰冻圈-水圈）及其对径流的影响。