The sediment load dramatically decreased at Zhangshui River watershed, the upper Ganjiang River of China. Quantitatively analyzing the contributions of anthropogenic and climatic factors on the reduction would be helpful of better understanding the dynamic of hydrological processes. Based on the longterm hydrological and meteorological series, this study was aimed to analyze the trends and change points of annual precipitation and sediment loads from 1956 to 2015 at Bashang gauging station of Zhangshui River watershed. It was realized by the help of the trend test, Pettitt test,and comparision of changes in the slope of cumulative annual measured data vs years between the two connected periods.Consequently,a significant decreasing trend was revealed in annual sediment loads, whereas insignificant decreasing trends were detected for annual precipitation and annual runoff, respectively. Meanwhile, there was a change point of annual sediment in 1994. By the benefit of the double accumulative curve(DMC) method between the accumulative annual rainfall to sediment, the relative change point was recognized to be 1995. According to this relative change point, the whole period was divided into two connected parts of 1956-1994 and 1995-2015.The contribution rate of remarkable decline of sediment load in the upper region of Ganjiang River watershed in 1995-2015 was also obtained when the rainfall was taken for the indicator of natural factor. As a result, the contribution rate of the human intervention to sediment load was 99.4% in 1995-2015, when the period of 1956-1994 was taken as a fundamental baseline. Integrating all these results, this paper could prove clearly that human intervention has a significant impress on rainfallsediment relationship of Zhangshui River watershed. Also it has an useful meaning as a method to evaluate the benefit of soil and water conservation measures. The study provides scientific foundation for understanding the causes of water resources decrease and significant information for water resources management under the influence of climate change and human activities.

Key words：rainfallsendiment relationship; ZhangRiver watershed; contribution rate of human intervention; rainfall erosivity；double cumulative curve