A comprehensive assessment framework for quantifying climatic and anthropogenic contributions to streamflow changes: A case study in a typical semi-arid North China basin

This study proposes to jointly use six Budyko framework-based methods, hydrological simulation, sensitivity indicator method, and empirical statistics to build a comprehensive assessment framework for quantifying climatic and anthropogenic contributions to streamflow changes. To evaluate its effectiveness, we conducted a case study in a typical northern semi-arid basin named Guanting in China. On average, human activities and climate change account for 80.22–81.51% and 18.49–19.78% of the streamflow decline in the two subbasins, i.e., Shixiali and Xiangshuipu, of the study basin during the 1984–1999 and 2000–2015 periods, respectively. Precipitation change outweighs potential evapotranspiration change as a primary climatic contributor of streamflow reduction in the two subbasins. In Xiangshuipu, the average precipitation elasticity of streamflow (εP) is 2.48 ± 0.23 and 2.56 ± 0.28 for the 1984–1999 and 2000–2015 periods, respectively, while εP in Shixiali has an average εP value of 2.49 ± 0.31 and 2.66 ± 0.32 during the two periods. Difference between the ten attribution methods varies between 5% and 12%, highlighting importance of applying this developed multi-method framework to avoid overestimation/underestimation and quantify uncertainty. This proposed comprehensive change attribution method is valuable for quantitatively distinguishing the relative contributions of external factors on hydrological regime changes.