Characteristics Of Water And Sediment In Zhouqu,Wudu And Bikou Hydrological Stations Of The Bailong River

The change of natural conditions and human activities will change the original natural water-sediment relationship of the river,which will have a great impact on the ecological environment of the whole river basin.This paper is based on the data series of precipitation,runoff and sediment transport at Zhouqu,Wudu and Bikou hydrological stations in the Bailong River from 1967 to 2016.These data are used to study the temporal variation of runoff and sediment flux and their correlation.The reasons causing the changes in runoff and sediment transport are also analyzed,except for the rule of relation between runoff and sediment in the Bailong River.It is of great scientific significance and practical application to understand the rule of river movement and the influence of human activities on the change of runoff and sediment.The following main results are obtained:(1)The maximum annual runoff of the three stations of Bailong River occurred in 1967,while the maximum sediment discharge occurred in 1984.The annual extreme-value ratio of runoff is less than that of sediment flux at three hydrological stations.(2)The interannual variation of sediment flux is obviously larger than that of runoff at Zhouqu,Wudu and Bikou hydrological stations of Bailong river basin.In terms of intraannual variation of runoff in the region,the annual non-uniform coefficient of runoff of each station showed a descend trend,manifesting that the annual distribution of runoff was becoming uniform.However,the distribution of sediment flux is irregular at all stations,with a decreased pattern at Wudu station and an increased pattern at the other two stations.(3)According to the obtained with the mutagenesis analysis and the periodicity analysis,the abrupt change points of annual runoff at all stations of Bailong River are relatively concentrated with a similar periodic rule.However,the abrupt changepoints of sediment flux are irregular and dispersed with an irregular periodic rule.The main reason is that river sediment transport is easily affected by natural environment change and human activities,thus,the mutability and periodicity of sediment flux are also more irregular and complex.(4)The fluctuations of runoff and sediment change in Bailong river basin are both affected by climate change and human activities.On the one hand,the excessive consumption of natural resources by human beings in the 1970 s and 1980 s has made much negative effect on the ecological environment of the Bailong River,resulting in serious soil erosion in the basin.On the other hand,the human activity,such as the Tianbao engineering,Program to Return Farmland to Forests and grassland,the water conservancy project,have played a positive effective role in water conservation and sand reduction.(5)The study found that river sediment transport is more susceptible to changes of natural conditions and human activities than runoff.The variations of runoff and sediment at Zhouqu station are less affected by natural conditions and human activities,indicated by a small fluctuation.However,the characteristics of runoff and sediment transport at Wudu station are obviously affected by the variations of natural environment and human activities.On the one hand,this region is characterized by loose geological conditions and heavy rain,thus flood often carry a large amount of sediment.On the other hand,the anural sediment content of the river decreases obviously,due to the gradual improvement of the ecological environment in Bailong River.For example,a low content of the sediment in recent years is found at the Bikou station,which are mainly affected by human activities,resulting in a significant reduction in sediment transport.