Analysis of Sediment Changes and Its Reasons of the Wuding River

According to the annual precipitation,runoff and sediment discharge data of Baijiachuan and Zhaoshiyao hydrological stations in Wuding River basin from 1956 to 2005,the paper analyzed the changes of the precipitation,runoff and sediment discharge with linear regression analysis,runs test,Kendall rank correlation test,Spearman rank correlation test and orderly cluster method. The results show that:a)The annual sediment discharge of the Baijiachuan and Zhaoshiyao hydrological stations is decreased significantly and there are trend component and jump components in the sequence;b)The annual runoff and sediment discharge changes are synchronized in Baijiachuan and Zhaoshiyao hydrological stations;c)The cumulative amount of sediment yield in the Baijiachuan and Zhaoshiyao hydrological stations are significantly lower than that of the trend of the cumulative amount of runoff,and the the annual sediment yield and the annual runoff has a strong correlation,and shows that runoff has a great impact on sediment discharge;d)Human activities is the main factor of the sediment's change in Wuding River basin.