Study On Runoff Generation And Concentration Characteristics In Xiaolihe Basin Under Condition Changing

Climate changes and human activities have great impact on hydrology and water resources, which is a hot issue in hydrology. Under the effect of climate and human activities, the characteristic of generation and concentration has changed, it is show that the runoff is decreased under the same rainfall condition. This paper takes Xiaolihe basin which is the typical basin in the middle of Yellow River as study area; studies the change on the characteristics of generation and concentration with distributed hydrological model and statistical method.Analyze the change on Xiaolihe basin's characteristic of runoff generation and concentration and the reason, through analyzing the change of annual rainfall,annual runoff,rainfall and runoff coefficient,rainfall and runoff relationship.In this paper, watershed characteristics are extracted with hydrology module in ArcView GIS, and the distributed hydrological model is built based on the digital elevation model data and hydrology technology. The model is used to analyze the impact of the rainfall characteristics and human activities on the rule of generation and concentration.The result shows that rainfall characteristics have changed in recent decades: rainfall has decreased; spatial distribution of rainfall has changed. The characteristics of rainfall play an important role in generation and concentration under the natural environment. With the increase of human activities, the runoff yield and peak discharge under the human activity are less than that under the natural environment; compared to the natural condition, watershed shows more sensitive than natural environment under the same rainfall intensity and antecedent soil water content, the under laying surface shows weaker storage properties; runoff yield and flood peak are larger when the rain center at the outlet of watershed under the natural environment, but it is not necessarily under the human activities environment.The change of rainfall and human activities result in the decrease of runoff, but human activity is the main factor.