中文摘要：

利用鄱阳湖流域1955-2003年3个主要水文站（外洲、李家渡、梅港）月径流实测资料，采用统计方法和小波方法，分析近50年该流域径流的年内、年际和周期变化特征。结果表明：鄱阳湖流域年内最大径流主要出现在4月、5月或6月；就季节变化而言，春季径流量最大，夏季次之，秋季和冬季较小。径流年际变化在开始较长时段呈增长趋势，1998年出现转折，之后递减，下降速度略低于前期增长速度。外洲等3水文站存在25～26a的第一主周期，8a和3-4a的次主周期，周期变化基本一致。通过对相应影响因素的分析，发现该流域径流变化是气候、流域覆被和水利工程等多种因素共同作用的结果，而气候因素中的降水和蒸发起着主要作用。

英文摘要：

Based on the monthly runoff series （1955-2003） of the three hydrological gauging stations, Waizhou, Lijiadu and Meigang within Poyang Lake watershed, statistical and wavelet methods are adopted to analyze the intra-armual, annual and periodic variation characteristics of the streamflows in the watershed for the last 50 years. The results show that： （1） the intra-annual stream flow presents a single-peak pattern with a peak value occurring in June, with the runoff in spring being larger than that in summer and autumn, and smallest, in winter. （2） In terms of the annual variation, stream flow increases towards 1998 and decreased thereafter, with the descending rate being smaller than the rising rate. （3） Variation of runoff exhibits a 25-year first dominant cycle and a 8-year or 3-4-year sub-dominant cycles at all three stations. The factors influencing the trend of stream flow are also investigated. Results indicate that the change of stream flow in Poyang Lake watershed is resulted from a combination of factors including climate （rainfall and evaporation）, land cover and the construction of hydraulic engineering schemes, among which rainfall and evaporation are the dominant factors. The outcomes of this study are of primary importance for reasonable water resources management for Poyang Lake watershed.