Analysis of impacts of climate variability and human activity on streamflow for a river basin in arid region of northwest China

In this study data from 8 catchments in the Shiyang river basin in the arid region of northwest China were analysed to investigate changes in annual streamflow over the past 50 years. The non-parametric Kendall test and the Pettitt test were used to identify trends and change points in the annual streamflow. It was found that 5 out of the 8 catchments had significant downward trends in annual streamflow. Change points in annual streamflow were identified in 4 catchments, which occurred in the year around 1961. A simple method was employed to evaluate the impacts of climate variability and human activities on mean annual streamflow based on precipitation and potential evapotranspiration. It was estimated that the climate variability accounted for over 64% of the reduction in mean annual streamflow mainly due to decreased precipitation. It was also shown that streamflow in the Shiyang river basin is more sensitive to changes in precipitation than potential evapotranspiration.