中文摘要：

主要依据长江中游和下游1470-2000年531年的旱涝等级资料,采用Mann-Kendall突变检测,功率谱分析及小波变换分析等方法探讨了长江中、下游地区的旱涝等级的频数特征、连旱连涝特征、旱涝变化的周期特征及其未来变化趋势。分析结果显示：长江中游的旱涝变化存在着准20年、准10年、准5年的周期变化,预测在21世纪的前5-10年,长江中游将处于降水正常及偏多期,而在21世纪10-20年代,则有可能出现少雨干旱期。而长江下游存在着准5年、准2年的周期变化,预测在21世纪的前10年,长江下游将处于多雨的洪涝期,而在21世纪10-20年代,则有可能出现少雨干旱期。

英文摘要：

This thsis utilizes 531 years grade materials of waterlogging and drought past 1470-2000 of midstream and downstream of the Changjiang River, by using several analyzing methods, such as Mann-Kendall sudden change measuring, analysis of the power spectrum and wavelet analysis, to study the characteristic and the trend changing of the waterlogging and drought of the midstream and downstream area of the Changjiang River. By using analysis of the power spectrum,we can get the remarkable change cycle dur- ing these times, and then, by using wavelet analysis, Some characteristic changed in time and the changing situation with time can be easily worked out. according to the above results. A deep research about the variation tendency of the drought and waterlogging of midstream and downstream of the Changjiang River can be made. The analyzing result shows that midstream and downstream area of the Changjiang River may be in drought in the following ten to fifteen years, And then waterlogging may control the midstream and downstream area of the Changjiang River for a long time.