Climate change dominates recent increase in streamflow in the Yellow River Basin

Since the operation of the Xiaolangdi Reservoir in 2002, the lower reaches of the Yellow River Basin have no longer experienced dried-up and the previously decreasing trend of streamflow has been reversed. However, the underlying physical mechanisms driving these hydrological changes remain unclear. In this study, we employ an improved hydrological model that integrates reservoir regulation, human water consumption, and inter-basin water diversion processes to quantify the respective contributions of climate change and various human activities to streamflow increases in each subbasin. Validation against monthly streamflow and reservoir storage observations shows that the improved hydrological model effectively simulates hydrological processes influenced by human activities, achieving NSE values ranging from 0.61 to 0.88 and PBIAS values below 17 % at nine mainstream hydrological stations. Multi-scenario modeling experiments suggest that climate-driven precipitation increases is the primary driver causing the increases in streamflow for most subbasins during 2002-2022. However, reservoir regulation exerts the dominant role in increasing streamflow in the Shizuishan-Toudaiguai subbasin. Our findings are crucial for promoting understanding of hydrological process changes in different subbasins of the Yellow River Basin.