A comprehensive framework for quantifying the impacts of climate change and human activities on baseflow and direct runoff: Application across six diverse basins in China

The source region of the Yellow River (SR-Yellow River), the Jinghe River, the Luanhe River, a partial region of the upper reaches of the Huai River (PRU-Huai River), the Ganjiang River, and the Dongjiang River Quantifying the impacts of climate change and human activities on runoff is essential for water resource protection and management. However, the respective effects on runoff components, specifically baseflow and direct runoff, remain insufficiently explored and quantified. This study proposes a comprehensive framework that combines several well-established methods, including an extended Budyko approach and baseflow separation, to assess climate and human impacts on annual and seasonal baseflow and direct runoff. Six basins across China were selected to assess the framework’s effectiveness. Results indicate that human activities are the dominant contributor to the decline in annual baseflow and direct runoff in the SR-Yellow River, Luanhe River, and Dongjiang River, accounting for 52.0–82.8 % of the total changes, while climate change had a greater influence on baseflow and direct runoff in the remaining basins, contributing 53.6–79.0 % of the variations in runoff components. Moreover, the impacts of both factors on baseflow and direct runoff were generally more pronounced in the rainy season than in the dry season, except in the PRU-Huai River. • A framework to quantify the impacts of climate change and human activities on runoff components is proposed. • Baseflow and direct runoff changes across six basins in China exhibit divergence. • Climate change and human activities have differential effects on runoff components. • The two factors exert a greater impact on runoff components during the rainy season.