Variation of Runoff and Sediment Discharge and Its Driving Factors in Xiangxi River Watershed in Three Gorges Reservior Area

[Objective]The objective of this study is to analyze the influences of precipitation and human activities on runoff and sediment load in order to provide basis for the benefits evaluation in soil and water conservation.[Methods]The variations of precipitation,runoff and sediment load during 1974—2010were analyzed in Xiangxi river watershed,by using Mann—Kendall test,linear regression,hydrological frequency curve and double mass curves.Factors that drive the variation of runoff and sediment discharge were quantified.[Results]There was a slightly declining trend in annual precipitation and annual runoff,while there was a significant decreasing trend(α=0.05)in sediment load.Mutation point analyses revealed that abrupt reduction in annual sediment discharge occurred in 1994,while the rapid reduction in annual runoff happened in1991.[Conclusion]Human activity is the main factor that drives the changes of runoff and sediment loads.