中文摘要：

被誉为“中华水塔”的三江源区具有丰富的贮水量，且与周边低海拔的巨大高差形成强大的水势差．自上世纪80年代以来，由于气候变化和人类活动共同作用下，水储量呈现下降趋势，径流过程减少和水塔功能减弱趋势明显．有关该区放牧干扰对草地植被群落改变及对生态水文过程的影响已引起学术界的普遍关注．本研究围绕三江源区水塔功能，草地生态系统环境特征，退化高寒草甸植被冠层对降雨、径流和蒸发的影响及退化草地对土壤水源涵养能力的影响，探讨了高寒草甸生态系统退化对黄河水塔的影响及作用机制和过程，简述了相关研究进展，提出了黄河流域水文过程研究存在的问题和未来重点发展的方向，对高寒草甸生态系统水循环的研究工作进行展望．

英文摘要：

The three- headwater- river- source region, known as ＂Water- tower of China＂, is not only the largest ecological zone functioning as water conservation in the country, but also holds huge difference of water potential to ambient lands at lower altitudes. Since 1980＇ s,land deterioration in alpine meadow region has been on due to climate change and activities of human beings, which reduces water runoff and weakens the water tower function. The issue is greatly concerned by both the academic circle and the public. This paper reviews current research on water tower function of the three - headwater - river - source re- gion, environment feature of alpine meadow ecosystem, and impact on water conservation capacity and effect on rainfall, runoff, and evaporation of vegetation degeneration, and discusses the mechanism and process of the Yellow river water - tower in re- sponse to grassland degeneration. Meanwhile this paper points out the existing problems in research on grassland ecosystem wa- ter cycling, and suggests possible further research.