中文摘要：

研究长江洪水和水资源问题，对于长江流域的可持续发展极为重要。本文以长江上游流域16个主要控制站径流观测数据为基础，对长江上游流域径流变化及其影响原因进行分析。结果表明，除金沙江流域径流微弱增加外，其他流域径流都有一定程度的减少趋势，其中岷江流域高场、横江流域横江、沱江流域李家湾、嘉陵江流域小河坝、武胜、北碚等站的径流显著减少，长江上游干流控制站寸滩站径流则微弱减少。针对流域气候变化与人类活动对水资源量的变化影响，建立大尺度分布式月水量平衡模型，将模型应用于长江上游的7个区间，模拟结果表明模型精度较高。最后应用分布式月水量平衡模型定量识别气候变化及人类活动对流域径流变化的贡献率，长江上游寸滩站径流减少，气候变化是主要影响因素，贡献率为71.43％；而岷江和嘉陵江流域的径流减小，人类活动贡献率大约占到一半。

英文摘要：

The Yangtze river from the source regions to the Yichang station is called as the Upper Yangtze River. Its area is about one million square kilometers. The main tributaries of the upper Yangtze River include the Jinsha River, Minjiang River, Tuojiang River, Jialing River and Wujiang River etc. It is desirable to study the variations of runoff at the major stations along the main stream and the major tributaries of the upper Yangtze River basin, and explore the possible causes of the variations, The runoff changes at sixteen main control stations in the upper reaches of Yangtze River basin were analyzed firstly. The results show that except in the Jinsha River basin, the runoff in the other basin decreased more or less. Among them, the runoff in the Minjiang River, Hengjiang River, Tuojiang River, and Jialing River decreased significantly. The runoff at the Cuntan station increased before 1968, and decreased significantly after 1993. According to water resources engineering and hydrologic station distribution, the upper Yangtze River basin was divided into seven areas： 1）Jinsha River basin; 2）Minjiang River basin; 3） Tuojiang River basin ; 4） Jialing River basin ; 5 ） Cuntan area; 6） Wujiang River basin ; 7 ） Yichang area. Then a large scale distributed monthly water balance model was developed and applied in the above seven areas. In the calibration period, the average value of Nash-Sutcliffe efficiency is 85.00% and that in the verification period is 81.69%. So the model can simulate monthly runoff well in the upper Yangtze River basin. Finally, the model was used to evaluate the impacts of climate change and human activities on the changes of runoff generation in the upper Yangtze River basin. Using the fixing-changing factor technique, the contribution rates of climate change and human activities on runoff change were evaluated. The runoff at the Cuntan station of Yangtze River decreased significantly since 1993 and climate change is the main factor that the contribution rate of which was 71.43