利用长江上游直门达水文站1963～2001年径流量及同期该流域气象资料,分析了长江上游径流量变化规律及其影响因子。研究表明:近40年来长江上游径流量呈减少趋势,其中以秋季径流量减少最为明显;长江上游流域夏季降水量减少、年平均气温升高和蒸发增大引起的气候干旱化趋势是造成径流量减少的主要原因,其中降水量是影响径流量的最主要因子;夏季降水量的减少与秋季径流量的减少关系密切,而秋季径流量的减少最终影响到了年径流量的减少。

Based on the runoff amount and meteorological data of the corresponding period in 1963～2001 at Zhimengda hydro station of the upper Yangtze River,the variation law and its impacting factor of runoff amount in the Yangtze River is analyzed.The result shows that the runoff amount of the upper Yangtze River has been decreasing in the recent 40 years,in which the decrement in autumn is more significant with the elevation/increase of annual air temperature and evaporation,and the decrease of precipitation as well as climatic desiccation. These factors have become the main cause for the decrease of runoff amount,among which precipitation is the most important factor to affect runoff amount,the precipitation decreasing in summer has a very close relationship with the decrease of runoff in autumn,while the decrease of runoff in autumn causes the decrease of annual runoff amount.