近47年来洞庭湖区干湿的气候变化

DROUGHT AND FLOOD CHANGE OF DONGTING LAKE BASIN IN RECENT 47 YEARS

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47年来洞庭湖区20个测站干湿指数(Z指数)进行了分析。研究表明:洞庭湖区20世纪60年代前期和80年代为干旱期,90年代为湿润期。80年代末有向湿润转变趋势,2003年后又开始向干旱转变。洞庭湖区干湿的年际变化较小,降水相对稳定,存在3年、6年和15年、22年4个特征时间尺度,且未来几年洞庭湖区将仍处于干旱期。洞庭湖区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北部、中部、南部和西北部4个区域。

The change of drought and flood in Dongting Lake Basin since recent 47years is analyzed using abrupt change analysis, wavelet analysis, coefficient of variance, EOF and REOF. The results showed that the 1990s were in flood periods, the 1960s and the 1980s were in drought period. There is a decreasing trend entering the 21st century, and there is an abrupt change from dry to wet 1980s. Generally, the Z Index presented variations of four periods. In the late 2000＇s, Dongting Lake Basin will be in a period of drought, after then will be in a period of flood. The most typical pattern of Z Index is the drought-flood consistence. The Z Index abnormal area can be divided into four： northern, the central, southern, northwestern.