Runoff response to changes in climate, vegetation cover, construction of terraces and check-dams, and urban expansion in the middle Yellow River

Understanding the controlling factors of spatial and temporal changes in runoff is critical for the integrated management and utilization of water resources. This study used the stepwise regression analysis to determine the expressions of eight regional controlling parameters and their climate and human factors in the middle Yellow River (MYR) based on the Budyko framework of the Fu equation. The contribution rate of climate and human factors to runoff change was analyzed using the elastic coefficient. The results showed that climate change caused runoff increase, and comprehensive human activities played an important role in runoff reduction. Human factors affecting runoff varied greatly in different regions. Vegetation restoration could lead to runoff reduction while constructing terraces and check-dams could cause an increase in runoff. Urban expansion contributed to runoff collection, and its contribution rate to runoff change was more than 200% in absolute value. The runoff change in the arid and semi-arid regions in the north was more sensitive to human factors.