<p>Climate change and human activities are primary drivers of runoff variations, significantly impacting the hydrological balance of river basins. In recent decades, the Yellow River Basin, China has experienced a marked decline in runoff, posing challenges to the sustainable development of regional water resources and ecosystem stability. To enhance the understanding of runoff dynamics in the basin, we selected the Dahei River Basin, a representative tributary in the upper reaches of the Yellow River Basin as the study area. A comprehensive analysis of runoff trends and contributing factors was conducted using the data on hydrology, meteorology, and water resource development and utilization. Abrupt change years of runoff series in the Dahei River Basin was identified by the Mann-Kendall and Pettitt tests: 1999 at Dianshang, Qixiaying, and Meidai hydrological stations and 1995 at Sanliang hydrological station. Through hydrological simulations based on the Variable Infiltration Capacity (VIC) model, we quantified the factors driving runoff evolution in the Dahei River Basin, with climate change contributing 9.92%–22.91% and human activities contributing 77.09%–90.08%. The Budyko hypothesis method provided similar results, with climate change contributing 13.06%–20.89% and human activities contributing 79.11%–86.94%. Both methods indicated that human activities, particularly water consumption, were dominant factors in the runoff variations of the Dahei River Basin. The integration of hydrological modeling with attribution analysis offers valuable insights into runoff evolution, facilitating adaptive strategies to mitigate water scarcity in arid and semi-arid areas.</p>