The water resource is insufficient and unevenly distributed in the Yellow River Basin, with great changes in annual and inter-annual runoff. With the impact of climate change and human activities, the strained relation between the supply and demand of water resource in the Yellow River Basin is likely to be further deteriorated. Due to the uncertainties in the climate change impact assessment, current forecasts for the future variation trend of runoff in the Yellow River Basin are inconsistent. This research takes climate change and social-economic development as the major driving factors for changes in water resources system of the Yellow River Basin and adopts climate model, hydrological model and scenarios of social-economic development as the main sources of the uncertainties influencing the assessment results. The author improves the simulation accuracy of climate model and hydrological model through multi-model weighting and improves the reliability of the scenarios of social-economic development through reasonable forecast of the key development parameters of social-economic development. The author also assesses the impact of climate change and social-economic development on the balance between the supply and demand of water resources in the Yellow River Basin, screens key factors influencing water security in the Yellow River Basin, and proposes applicable countermeasures for future water management in the Yellow River Basin. The main contents and conclusions are as follows:
(1) According to the comparison, which adopts deviations, root mean square errors, simple correlation coefficients and spatial correlation coefficients as the indicators, between the 20C3M outputs of the 8 GCM models downloaded from IPCC Data Center and the measured data from ground meteorological station, MIROC-m is the best model for air temperature simulation and CSIRO30 is a preferable model for the simulation of precipitation. All in all, the outputs of GCM can simulate the air temperature in the Yellow River Basin well, but the outputs are not ideal for the simulation of precipitation.