近50年湘江流域干湿气候变化若干特点

采用M-K突变、小波分析、空间变异系数、经验正交函数分解法（EOF）和旋转经验正交函数分解法（REOF）等方法,对近48年来湘江流域40个测站干湿指数（Z指数）进行了分析。研究表明：湘江流域1960年代前期和1980年代为干旱期,1990年代为湿润期。1980年代末有向湿润转变趋势,2003年后又开始向干旱转变。湘江流域干湿的年际变化较小,降水相对稳定,存在3年、6年和10年和21年4个特征时间尺度,且未来几年湘江流域将仍处于干旱期。湘江流域干湿变化具有很好的主体一致性,依据空间异常类型可分为南部、中部、北部和西南部4个区域。

Characteristics of Drought and Flood Climate Changes of Xiangjiang River Basin in Recent 50 Years

The change of drought and flood in Xiangjiang River Basin in recent 48 years is discussed by using abrupt change analysis, wavelet analysis, coefficient of variance, EOF and REOF. The results show that the 1990s is in flood periods, and the 1960s and the 1980s is in drought period. There is a decreasing trend since the 21st century, and there is an abrupt change from dry climate to wet climate in 1980s. Generally, the Z Index presents variations of four periods. In the late 2000s, Xiangjiang River Basin would be in a period of drought, and would be in a period of flood afterwards. The most typical pattern of Z Index is the drought-flood consistence. The Z Index abnormal area can be divided into four as the southern, central, northern and southwestern regions.