The Evolution Trend and Motivating Factors of Runoff in Yang River Basin

Based on long-term hydrological and meteorological observation data,the runoff change was analyzed on different time-scales monthly,annual and inter-decadal,and in representative dry-and wet-years in Yang River Basin with numerical analysis method.And also,Regression analysis was used to establish the correlation between runoff and precipitation at different time-scales.More importantly,however,precipitationrunoff mode was adopted to quantify the impact of human activity and climate change on runoff,and the respective impact of human activity and climate change on runoff isolated.Results showed that runoff was experiencing a great decrease especially after the 1980s,besides the impact of climate change,human activities such as industrial and agriculture water use,the increase of domestic water taken for rapid population growth,soil and water conservation measures as reservoir water storage were the main reasons of runoff decrease.And on average,83.2% of total runoff decrease was driven by human activities.