中文摘要：

为了得到洞庭湖流域降雨变化特征,综合运用Mann-Kendall统计检验法及Morlet小波函数,对洞庭湖流域1960-2008年降雨时间序列进行了分析.研究结果表明,1960-2008年间,年降雨序列呈微弱增加的趋势,进入21世纪后降雨量呈显著减少的趋势;1960-2005年年降雨量变化的特征时间尺度为3、7、24年,汛期降雨量变化的特征时间尺度为3、7、16年;根据主周期降雨量变化可以预测,2006-2008年年降雨量和汛期降雨量均将处于偏少水平,其结论与实际数据相吻合,验证了Morlet小波分析法对于降雨量趋势预测的有效性.

英文摘要：

In order to study the variations characteristics of rainfall in the Dongting Lake Watershed,the method of MannKendall test and Morlet wavelet function were used to analyze the rainfall time series during the period of 1960-2008 in Dongting Lake Watershed.The research results showed that the annual rainfall series took on a weak increasing trend during the period of 1960-2008,while a remarkable decreasing tendency arose after entering the 21st century.The characteristic time scales of changes in annual rainfall were 3,7 and 24 years,and the characteristic time scales of changes in flood season rainfall were 3,7 and 16 years during the period of 1960-2005.According to the analysis of major period of changes in rainfall,it could be conjectured the annual rainfall and flood season rainfall would both be less than the normal level during the period of 2006-2008,which agrees well with the data.The Morlet wavelet analysis method proved to be feasible in prediction of rainfall trends in the future.