Runoff Composition Of The Yarlung Zangbo River And Its Response To Cliamte Change

The Tibetan Plateau known as the Asian Water Tower provides a large amount of water to more than 2 billion of the world's population,and The Yarlung Zangbo River originates from the Jiemayangzong glacier at the northern foot of the Himalayas in the south of the Qinghai Tibet Plateau.It is an important international river and the highest River in the world.Due to the complex terrain and harsh climate of the Tibetan Plateau,the measured data are relatively scarce,which makes the research more difficult.Although previous studies have been made on climate change and runoff variation pattern within the Yarlung Zangbo River basin,the relative contribution of rainfall,snow melt,glacier melt and base flow to the runoff has not been studied in detail.In this study,a distributed hydrological model was used and corrected through the measured daily runoff of Nuxia hydrological station,and then a relative reliable Spatial Processes in Hydrology(SPHY)model that can reflect the current situation of the Yarlung Zangbo River basin was constructed.Based on the good performance of that model,the spatial and temporal distribution characteristics of hydrologic cycle in the Yarlung Zangbo River basin was analyzed,and the contribution of the four water sources to runoff in the Yarlung Zangbo River is quantitatively calculated.The results show that the component of rainfall plays an important role in the whole basin and become the controlling component of the runoff change in most areas.The snow melt water is particularly important for the runoff change in the Lhasa river basin.Glacial melt-water,distributing in the downstream with many glaciers,such as the Nu Xia station and De Xin station,becomes a runoff control component of that region.The base flow in the whole basin contributes about 10% to the runoff,relatively small but guarantees the basic flow of the Yarlung Zangbo River basin.By the middle of this century,the runoff in the Yarlung Zangbo River Basin is expected to increase by about 15% under warm and wet conditions,of which the rainfall runoff growth is about 19% and the glacier melt water growth is about 11%.In many climate scenarios,the runoff components show significant growth characteristics.