Abstract:

By taking the source region of the Yangtze River and the Yellow River as research object,the suitability of largescale semidistributed hydrologic model (Variable Infiltration Capacity,VIC) was tested by using observed daily maximum ground temperature,daily minimum ground temperature and daily precipitation data of the source region of the Yangtze River,the Yellow River and their surrounding in 1980~1999.The results showed that VIC model was suitable to simulate the runoff of the source region of the Yangtze River and the Yellow River.The NASH coefficient and correlation coefficient of VIC in the source region of the Yangtze River was 0853 3 and 0930 2,respectively,while that in the source region of the Yellow River was 0889 3 and 0924 8,respectively.Then by using the validated largescale distributed hydrology model and high resolution dynamic downscaling meteorological forcing data,the possible trends in runoff of the source region of the Yangtze River and the Yellow River were analyzed under future climate warming.The average annual runoff of the source region of the Yangtze River and the Yellow River will increase by 858% and 919% in the future 30 to 50 years,respectively.In the future 80 to 100 years,it will increase by 1716% and 721%.And relative to the annual precipitation of 2030~2049,the annual precipitation of 2080~2099 will increase up 006 mm/day,but the average annual runoff of the source of the Yellow River will reduce only by 198% in the next 50 years.The variations of runoff in the source area of the Yangtze River and the Yellow River were analyzed by using the high resolution dynamic downscaling as meteorological input data for the future 30 to 50 years,based on four scenario simulations of the land use/cover change.The impact of different vegetation cover type on runoff was compared.These results indicate that the runoff is the minimum at forest land,but that is the maximum at bare land.