基于标准降水指数的广西旱涝特征演变分析

利用广西地区74个气象站1961-2008年月降水资料,采用标准降水指数、Mann-Kendall检验、旋转经验正交函数(REOF)等方法,分析了广西地区近48年旱涝时空变化特征。结果表明:①广西旱涝呈阶段性变化,20世纪60年代、80年代中后期至90年代初期、21世纪以来旱涝灾害以干旱为主,70年代至80年代中期、90年代中后期的旱涝灾害以洪涝为主。②通过REOF对广西进行旱涝分区,根据前4个旋转空间模上高荷载区分布,广西可以大致分为桂东北、桂西北、桂东南和桂西南4大区域,各分区的极端旱涝变化总体上和全区保持一致性,但在某些时段不同区域之间重度旱涝存在一定的差异性。桂东北和桂东南地区重旱发生的频率大于其他地区,桂西南的重涝发生的频率大。

Analysis of Drought-flood Spatio-temporal Characteristics Based on Standard Precipitation Index in Guangxi

The spatio-temporal characteristics of flood and drought in Guangxi were analyzed using standardized precipitation index, Mann-Kendall test and REOF based on the observed monthly precipitation data of 74 meteorological stations from 1961 to 2008. The results indicate that: (1) flood and drought disasters have stage characteristics, i-e. Droughts were frequent in 1960s, mid 1980s to early 1990s and the 21-st -century, while floods were severe and frequent during 1970s to early 1980s and in the late 1990s; (2) Guangxi can be divided into four regions, northeast Guangxi, northwest Guangxi, southeast Guangxi and southwest Guangxi, which have similar trends of extreme flood and drought disasters to the whole region. Sometimes there are some differences between severe drought and flood in different areas. The frequency of severe drought occurred in northeast and southeast Guangxi is higher than other regions. However, the frequency of severe flood occurred in southwest Guangxi is high.