Separation of the impacts of climate change and human activity on runoff variations

A practical approach to separate the impact of the processes of climate change (CC) and human activities (HA) on streamflow is presented. A non-parametric Mann-Kendall-Sneyers test, combined with moving t test and Yamamoto methods, was used to recognize abrupt change points in the runoff time series to determine a baseline period. A new algorithm to separate CC and HA influence on streamflow was deduced based on the climate elasticity concept. Application to the Chao River, China, shows that CC imposed a positive impact on streamflow in this region (25%, on average), while HA exerted a continuous negative impact of -75% in the period after the 1950s. These results are of great use in understanding the variation of CC and HA impacts under different human development patterns. [GRAPHICS] Editor Z.W. Kundzewicz; Associate editor H. Akso