Projected changes of runoff in the Upper Yellow River Basin under shared socioeconomic pathways

Climate change has significantly impacted the1 water resources and conservation area of the Yellow River basin. The Upper Yellow River basin (UYR), referring to the area above Lanzhou station on the Yellow River is the focus of this study, the runoff changes in the UYR would greatly impact the water resources in China. Most existing studies rely on a single hydrological model (HM) to evaluate runoff changes instead of multiple models and criteria. In terms of the UYR, outputs of the previous Coupled Model International Comparison Project (CMIP) are used as drivers of HMs. In this study, the weighted results of three HMs were evaluated using multiple criteria to investigate the projected changes in discharge in the UYR using the Shared Socioeconomic Pathways (SSPs) from CMIP6. The research’s key findings include the following. 1) Annual discharge in the UYR is expected to increase by 15.2%–64.4% at the end of the 21st century under the 7 SSPs. In the long-term (2081–2100), the summer and autumn discharge will increase by 18.9%–56.6% and 11.8%–70%, respectively. 2) The risk of flooding in the UYR is likely to increase in the three future periods (2021–2040, 2041–2060, 2081–2100) under all 7 SSPs. Furthermore, the drought risk will decrease under most scenarios in all three future periods. The verified HMs and the latest SSPs are applied in this study to provide basin-scale climate impact projections for the UYR to support water resource management.