The effect of climate change and human activities on runoff in the middle reaches of the Yangtze River

The impacts of climate change and human activities on runoff in the middle reaches of the Yangtze River were investigated with four approaches:the cumulative anomaly method, Mann-Kendall test, ordered clustering method and multiple linear empirical model. It is found that runoff has slowly decreased linearly for many years with precipitation change. 1968 and 2006 were the runoff abrupt change years.From 1969 through 2005, the human activities in the catchments controlled by Zhicheng, Shashi, Jianli, Chenglingji and Luoshan stations had contributed 85.68%, 50.89%, 84.78%, 89.81% and 68.39%, respectively, to the runoff decrease.From 2006 to 2014, the human activities in the catchments had contributed 88.40%, 59.47%, 82.86%, 80.03% and 63.63%, respectively, to the runoff decrease. The contribution ratio of human activity is higher than that of climate change.