Abstract:

Based on the meteorological and runoff data of the ThreeRiver Headwater Region during 1961~2007,the change trend of climatic and hydrological factors and the tendency predict in the future were analyzed by the MannKendall technique and Rescaled range analysis.Meanwhile,principal component analysis was used to judge the main driving factor.The results showed that air temperature increased sharply and water surface evaporation and soil temperature increased with the increase of air temperature,whereas the increasing tendency of precipitation was unremarkable.The annual runoff,especially summer and autumn runoff,reduced sharply and the runoff coefficient also showed a decreasing trend.The result of Rescaled range analysis showed that the variation trend of future was identical to the past.The air temperature, soil temperature and water surface evaporation were the leading driving factors of the runoff process,and the increase of them caused the decrease of runoff. However,the increase of precipitation caused the increase of runoff.This study should be helpful for local water resources planning and management,and also should be significant for the study of the influence of global warming on ecosystem evolution,permafrost degradation and water resources safety.