Abstract:

On the basis of climate and hydrology database from 1961 to 2003,the MannKendall test and linear trend method were used to detect the longterm trend of runoff in Zipingpu and Gaochang hydrological station in Minjiang Basin,and the temperature and precipitation over Tibetan Plateau.The response of characteristic of runoff in Minjiang Basin to temperature and precipitation over Tibetan Plateau was researched by using Pearson correlation analysis method.The result shows that:(1) As a whole,there was a decreasing trend in runoff in Zipingpu and Gaochang hydrological station in Minjiang Basin when there was an obvious increasing trend in temperature，while there was a weakly increasing trend in precipitation over Tibetan Plateau during the past 43 years.The annual runoff in Zipingpu hydrological station showed a significant and continuous decrease with the 5% level of significance and the decreasing rate was -2.619 0 m3/s/year.The slope was -6.538 5m3/s/year in Gaochang hydrological station.The runoff in the 1960s and the late 1980s was increasing,but decreasing in the early 1970s and period from 1990 to 2003.As for seasonal variation,the runoff reduction primarily took place in summer and autumn,but very small in spring.(2)As the temperature over Tibetan Plateau increased,the runoff in Zipingpu and Gaochang hydrological station in Minjiang Basin decreased.The correlation between precipitation over Tibetan Plateau and runoff in Minjiang Basin varied with different section of Minjiang River and different season,for example,there were significant correlation between precipitation over Tibetan Plateau and runoff in spring in Minjiang Basin,there was a weakly negatively correlated between precipitation over Tibetan Plateau and runoff in Zipingpu hydrological station in Minjiang Basin,and the precipitation over Tibetan Plateau have strong positive correlation with runoff in Gaochang hydrological station in Minjiang Basin.Besides,there was a time lag for the effect of climate change over Tibetan Plateau on runoff in Minjiang Basin .