Objective The analysis of runoff evolution trends and the quantitative assessment of the impacts of both climate change and human activities on annual runoff are critically important for achieving efficient and rational utilization of water resources, promoting ecological construction, and ensuring sustainable socioeconomic development within river basins.

Methods Based on runoff and precipitation data for the Yihe River Basin from 1951 to 2020, this study employed the Mann-Kendall trend test and a time series comparison method to analyze variation trends in annual precipitation and runoff. An empirical statistical precipitation–runoff model was then used to quantify the impacts of precipitation change and human activities on annual runoff, thereby revealing the evolutionary mechanisms of annual runoff in the basin.

Results The results indicated that from 1951 to 2020, annual precipitation and annual runoff in the Yihe River Basin both exhibited a declining trend. Human activities, including water conservancy projects, water resource development and utilization, ecological construction, and land use change, led to a reduction in annual runoff. The runoff evolution process could be divided into a baseline period (1951−1965) and an intervention period (1966−2020). During the baseline period, annual runoff variations were predominantly influenced by precipitation changes. In the intervention period, runoff was jointly affected by precipitation and human activities, and the impact of human activities was relatively larger.

Conclusions The findings can provide a scientific basis for the Yihe River Basin to coordinate ecological construction with water resource development and utilization, and to formulate differentiated water resource management strategies in the context of intensifying human activities.