Assessing the effects of climate change and human activities on runoff variations from a seasonal perspective

Abstract

Previous studies attempting to quantify the contributions of climate change and human activities to runoff variations in a changing environment have widely focused on an annual scale, while seasonal scales are rarely involved. China is the largest socialist country in the world, and its economic development is affected by its Five-year Plan policy. To this end, the upper Han River Basin, the largest tributary of the Yangtze River Basin, was selected as a case study. A seasonal-scale Budyko framework was extended based on the monthly abcd model in this study for quantifying the effects of climate and human activities changes on seasonal runoff variations, especially exploring the effect of China’s Five-year Plan policy. Results disclose that: (1) the change point in the annual runoff series is 1990, and the monthly abcd model achieves good performance in the prechange and postchange period; (2) the relative contribution of climate change to runoff variations is 62.99%, 70.20%, 87.54%, and 90.30% in spring, summer, autumn, and winter, respectively, indicating that climate change is the dominant factor controlling runoff variations in every season; (3) the contributions of climate change and human activities show obvious dynamic and seasonal characteristics, which are strongly impacted by the implementation of the Five-year Plan policy. Generally, the findings of this study provide valuable references for local reasonable water resource planning and management to make timely and appropriate use of the water supply.