The principle and methods of base flow index(BFI) and line separation have been employed to calculate the baseflow in 13 hydrologic sections on the main stream and 31 hydrologic sections on 20 major tributaries of the Yellow River basin.Based on the baseflow separation results,a comprehensive analysis was made on the forming mechanism of baseflow,the contribution of groundwater to the Yellow River,baseflow changes,the composition and the total amount of groundwater resources in the basin,which has provided ...