Abstract:

As an important component and existing form of water resources,surface runoff is an important link to the water cycle and an essential element of water balance.It is also the most important source of water for socio-economic development.Through studying the characteristics of runoff variability in the basin,a scientific basis was provided for comprehensive management of regional water resources,rational development,and protection of ecological environment.As the third largest inland river basin in the Hexi Corridor,Gansu Province in northwestern China,the Shule River Basin is an important ecological security barrier for China.Due to the excessive development and utilization of water resources in river basins,ecological and environmental problems such as vegetation degradation and reduction of wetlands in river basins are becoming more prominent.At the same time,with the continuous development of population,economy,and society,the demand for water resources continuously increases,seriously affecting and restricting the coordinated and sustainable development of regional eco-environment and socio-economics.Therefore,the purpose of this study was to analyze the characteristics of runoff fluctuation in the mainstream of the Shule River Basin and to grasp the dynamic changes of water resources in the river basin.The measured monthly and yearly runoff data of Changmabao,Panjiazhuang,and Shuangtaobao hydrological stations in the mainstream of the Shule River Basin were selected as the basic data.The characteristics of annual,interannual,and seasonal variations,and runoff mutation in the mainstream of the Shule River Basin were analyzed using linear tendency,cumulative anomaly,moving average,and the Mann-Kendall mutation test in the period 1956-2016.The annual runoff of the mainstream of the Shule River showed an overall increasing trend,and the annual runoff rates were ranked as follows: Changmabao Station (1.075 × 10⁸ m³·(10 a)^-1)> Shuangtabao Reservoir Station (0.253 × 10⁸ m³·(10 a)^-1) > Panjiazhuang Station (0.126 × 10⁸ m³·(10 a)^-1) from 1956 to 2016.The distribution of annual runoff was extremely uneven,mainly concentrated from May to September,accounting for over 50% of the total annual runoff.The interannual change in runoff in the 1970s to 1990s was lower than the multi-year average runoff,was higher than the multi-year average runoff of the 21st century.The seasonal variations in runoff showed different characteristics at each station,and the increase in summer runoff at each station greatly contributed to the annual runoff.At the same time,the average anomaly of runoff in different seasons and different ages showed different characteristics.The average annual runoff mutation showed different mutation characteristics and different mutation times,and the mutation points of Changmabao Station,Panjiazhuang Station,and Shuangtaobao Reservoir Station were 1998,2012,and 2006,respectively.The results of the study showed certain reference functions to facilitate smooth implementation of key management program in the Dunhuang water resources for reasonable utilization and ecological protection.The results also provided important practical references for promoting regional integrated water resources management,scientific allocation,guiding regional long-term integrated water resources planning,and socio-economic development.The follow-up study must further discover the characteristics and prediction of regional runoff changes under changing environment (climate change and human activities).The extent of impacts of human activities and climate change on runoff should be quantitatively described to provide references for scientific regulation of regional water resources.

Key words: runoff')">

runoff, variation characteristics, mainstream of Shule River