Analysis of multi-temporal runoff variation and influencing factors in the upper reaches of the Han River, China

Abstract

Climate change and human activities significantly affect basin hydrology and water resources, with the Han River basin (HRB) ranking among China’s critical sources. To quantitatively evaluate the impact of climate change and human activities on multi-temporal scale runoff changes in the HRB, Mann Kendall test and B-G segmentation algorithm were used to analyze the trend of runoff changes, annual distribution characteristics, and mutation years, respectively. Next, the actual evaporation in the HRB was simulated using the monthly ABCD model. Finally, the impact of climate change and human activities on the surface runoff in the HRB was calculated using the seasonal Budyko formula. The results showed that: (1) The overall runoff of Ankang Hydrological Station in the HRB showed an insignificant downward trend from 1961 to 2015. (2) The annual distribution of runoff in the HRB from 1961 to 2015 showed a clear “bimodal” pattern. (3) The year of runoff mutation in the HRB from 1961 to 2015 was determined to be 1985. (4) The contributions of climate change and human activities to annual runoff were 81.61 % and 18.39 %, respectively. Climate change was the main factor leading to changes in runoff.