雅鲁藏布江流域气候和下垫面变化对径流的影响研究

典型高原寒区雅鲁藏布江流域径流变化是反映该区域气候和下垫面变化的重要指标。在全球升温背景下，由于观测资料稀缺，导致缺乏针对整个流域的气候和下垫面变化对径流影响的研究。因此，本研究基于1986—2010年的气象数据和奴下水文站月尺度、动态土地利用数据等，利用改进的水文模型并结合不同的模拟策略厘清了流域1991—2010年不同时段间气候和下垫面变化对径流的影响。结果表明：在1991—2010年期间，不同时段间气候和下垫面变化对径流变化的贡献率差异较大，气候变化对径流变化的贡献率高于下垫面变化，且使径流量增加。从空间上看，气候变化对流域产流的贡献率在上游和中游都较大，在下游东北部的贡献率较小，而在该区域下垫面变化的贡献率较大。雪冰融水径流呈增加的趋势，对年径流的平均贡献率在21.1%~48.6%范围内，多年平均贡献率为33.6%；雪冰融水径流一般从4月开始增大，8月达到最大，10月达到消融末期。本研究的开展和发现既是雅鲁藏布江流域水文、水资源基础性研究的需要，具有重要的理论研究意义，同时也可为该流域的水资源保护、规划与管理提供科学理论和决策依据，具有重要的现实意义。

Study on the influence of climate and underlying surface change on runoff in the Yarlung Zangbo River basin

Runoff variation is an important indicator reflecting the regional climate and underlying surface changes in the typical plateau region， Yarlung Zangbo River basin. Facing the global warming， there is still a lack of study on the influence of climate and underlying surface changes on the runoff of the Yarlung Zangbo River Basin because of its scarce observation data. Therefore， based on the daily meteorological data and the monthly hydrological data of Nuxia station during 1986—2010， as well as dynamic land use data， this study comprehensively investigated the influence of climate and underlying surface changes on runoff at different period from 1991 to 2010 in the Yarlung Zangbo River basin， with the final goal of clarifying the discharge variation mechanism of the high-altitude watershed by means of the improved distributed hydrological model in association with different simulation strategies. The results suggested that： （1） During 1991—2010， the contribution rate of climate change and underlying surface change to runoff variation varied greatly in different periods， and the contribution rate of climate change to runoff variation was higher than that of underlying surface change， which increased runoff during the period. （2） In spatial perspective， the contribution of climate change to runoff was larger in the upper and middle reaches， but smaller in the northeast of the lower reaches where the underlying surface changes contributed relatively large. （3） Runoff from snow and ice ablations tended to increase with climate warming， their average contribution to the annual total runoff of the basin was in the range of 21.1% to 48.6% approximately， and the average long-term contribution was about 33.6%. The snow-ice melting runoff started to increase from April of a year， reached to the maximum in August of the year， and approached to the end of ablation in October in general. The implementation and findings of this study is not only the need of basic research on hydrology and water resources in the Yarlung Zangbo River basin， but also has important theoretical significance. At the same time， it can also provide scientific theory and decision-making basis for the protection， planning and management of water resources in the basin， which has important practical significance.