Analysis of the trend in surface runoff discharge from the Gannan Plateau
[Objective]The Gannan Plateau is an important runoff production area in the upper reaches of the Bailong River in the Yellow River and Yangtze River basins.The development trend of the regional production surface runoff is analyzed to provide a basis for optimizing the sustainable development and use of water resources.[Method]This article takes the Gannan Plateau as the research area and is based on 66 years of measured runoff data from 16 control hydrological stations,including Maqu,Shuangcheng,Minxian and Zhouqu.Propose the concept of using measured runoff to evaluate the external output of surface runoff within an area.The development trend of measured runoff and output surface runoff of the mainstream of the Yellow River,Taohe River,Daxia River and Bailong River in the region is analyzed using multiple trend mutation test methods,ARIMA model and other methods.[Result]The measured runoff at the representa-tive station of Gannan Plateau only at Maqu Station shows an increasing trend,while that at the other sta-tions in Minxian County of Taohe River,Shuangcheng of Daxia River and Zhouqu of Bailong River shows a decreasing trend,and the measured runoff mutation points at each station are significant.The surface runoff output from the Gannan Plateau to the outside world is 8.07 billion m3,showing an insignificant decreasing trend,with a reduction rate of 136 million m3/10 a,and the year of the mutation point is 1989.The contribu-tion rate of surface runoff output from the Yellow River Basin to the measured runoff at the downstream Lanzhou Hydrological Station is 21.1%on average over the years,showing a decreasing trend,with a re-duction rate of 18 million m3/10 a.The annual average contribution rate of the Bailong River in the Yangtze River Basin to the downstream Wudu Hydrological Station is 37.3%,showing an increasing trend,with an increase rate of 14 million m3/10 a.The predicted surface runoff output in 2023 and 2024 is 7.879 billion m3 and 7.783 billion m3,respectively.[Conclusion]Due to the effects of climate change and human activities,surface runoff from the Gannan Plateau has been decreasing for more than 30 years since 1990.This conclu-sion is of great significance for the development and utilization of water resources and economic and social development in the lower reaches of the Gannan Plateau and deserves high attention.