Precipitation

daily temperature and evaporation data from 28 meteorological stations and 4 evaporation stations

and daily streamflow data from 4 hydrological stations during 1959-2000 are analyzed by using the elastic coefficient method and the W-ANN model. Besides

construction of water reservoirs and land use changes are also considered in the analysis to investigate fractional contributions of climate changes and human activities as driving factors to streamflow variations. The results indicate that: ① the change point of the streamflow of the East River Basin occurred in 1972

the streamflow was larger after 1972 than before 1972; ② The increased precipitation and decreased evaporation resulted in the increase of streamflow. The fractional contribution of climate change to the increase of the streamflow is 0.27~0.77; ③ Human activities led to the increase of the streamflow via changes of land use. Meanwhile

the construction of water reservoirs or hydraulic facilities tends to modify the annual distribution of the streamflow significantly. The fractional contribution of human activities to the increase of the streamflow is 0.23~0.73 and the fractional contribution decreases from the upper to the lower East River basin. This research has theoretical and practical contribution to human knowledge of the driving factors behind streamflow variations and also to the scientific water resources management of the East River basin.