【摘要】 青藏高原被称为世界"第三极",又有"亚洲水塔"之称,对其周边地区的水文和气候系统有重要影响.青藏高原是亚洲许多大河的发源地,其冰川与河川径流变化影响到周边数十亿人口.本文介绍了青藏高原河川径流观测现状,回顾了青藏高原河川径流变化研究. 20世纪50年代至21世纪初,黄河源区年径流呈减少趋势、长江源区年径流呈微弱增加趋势,青藏高原其他江河源区的年径流没有显著的变化趋势.黄河上游、澜沧江上游、沱沱河及拉萨河源区的春季径流有增加趋势.未来气候变化情景下,随着降水和冰雪融水增加,青藏高原大部分河流源区径流增加,洪水等极端水文事件发生更加频繁.青藏高原河流源区水文气象观测资料稀缺,是河川径流变化及其影响研究的重大挑战.青藏高原水文研究亟需结合最新观测与模拟技术,提高水循环观测与模拟能力,深入认识青藏高原河川径流复杂性及其变化规律,为径流变化的影响评估及其应对提供科技支撑.更多还原

【Abstract】 The Qinghai-Tibet Plateau(QTP), also often called the Third Pole, is considered the Asian Water Tower because it is the source of many major Asian rivers. The environmental change on the QTP can affect the climate system over the surrounding area, and the changes in glacier and river streamflow on the QTP will lead to cascading impacts in downstream area where billions of people live. This paper reviews the hydrological observations and streamflow changes of the major Asian rivers originating from the QTP. From the 1950 s to the beginning of the 21 st century, streamflow on the QTP overall shows large interannual variations but no significant trends. The monthly mean streamflows during the flooding seasons are the largest in the 1960 s for the outlet stations on the QTP. Annual streamflow in the source region of the Yellow River decreased while that in the source region of the Yangtze River increased slightly. No significant trends of annual streamflow have been reported for the other river source regions. The mean streamflows during peak season are relatively large in the 2000 s at the river source region(upper reaches) of most rivers on the QTP. An increasing trend of streamflow in spring has been found in the upper reaches of the Yellow River, the Lancang River, the Tuotuo River(of the Yangtze River),and the Lhasa River(of the Yarlung Zangbo River). The largest month of streamflow often appears in July for most stations, but in August at the Lhasa and Nuxia stations which are located in the Yarlung Zangbo River. Streamflow changes on the QTP could be mainly attributed to changes in snow and ice, as little influence from direct human activities were found. However, the examination of the streamflow changes largely relies on the hydrological observations. So far, due to data unavailability, we are still unclear about the long-term change in the streamflow on the QTP, especially the changes in recent years. The changes in ice and snow pack on the QTP could have significant impact on the downstream water resources and ecosystem. As more water resources have been generated from ice/snow melting, from a long-term perspective, water resources would be reduced along with shrinking and disappearing glaciers.Hydrological projections under future climate change suggest that streamflow in most river source regions would increase along with precipitation and increases in ice/snow melting, and hydrological extremes such as flooding would occur more frequently. Large uncertainties across Generic Circulation Models(GCMs) and hydrological models have been found in future projections of streamflow on the QTP. Reduction of ice/snow melting would aggravate the water stress conditions for both the ecosystem and human society on the QTP and its downstream areas. Sparse hydrometeorological observations in the past, particularly in the remote region of the QTP, are a major limiting factor to studies on streamflow change and its impacts. Further efforts are urgently needed to combine the advanced observation and modeling technologies to improve the observation and simulation capabilities of the water cycle over the QTP, and to provide scientific and technological support for coping with the accelerated ice/snow melting, increasing hydrological extremes and their impacts over the QTP.更多还原