Impact of climate change and human activity on the runoff of Wei River basin to the Yellow River

Based on the data of temperature,precipitation,recorded runoff,water consumption and area of water and soil conservation,the impact of climate change and human activities on the runoff of Wei River basin to the Yellow River was studied according to the use of the regression method.The method of Kendall's rank correlation was applied to test the trend of climate factors.Precipitation was selected as the factor of climate change,and water and soil conservation,surface water consumption,groundwater exploitation around bank side of Wei River which intensify the replenishment of the river water to groundwater,and rainwater collection were selected as the factors of human activity.The results show that the changes of precipitation from different areas of runoff generating have different impacts on the runoff to the Yellow River.Compared with average annual runoff in many years,the average annual runoff in 1990's decreased 29.04×108 m3.The average annual precipitation decreased 10.4%,which resulted in the runoff decreased of 68.2% of total decreased runoff.And the decreased runoff amounts resulting from the human activity,factors of water and soil conservation,surface water consumption,groundwater exploitation and rainwater collection were 11.8%,10.1,9.8% and 0.2% of total runoff deceased respectively.