基于EMD的洪涝灾害成灾面积波动的多时间尺度分析——以湖南省为例

应用经验模态分解(EMD)方法分析了湖南省1949~2002年洪涝灾害成灾面积波动情况。结果表明:湖南省洪涝灾害成灾面积存在着准3年、准8年和准22年左右特征时间尺度的周期性波动;分析各时间尺度周期性振荡的贡献率,其中以准3年时间尺度成灾面积振荡的贡献最大,即湖南省洪涝灾害成灾面积波动以准3年时间尺度为主;从各时间尺度的振荡看,自20世纪80年代中期以来,洪涝灾害成灾面积的波动频率增加,洪涝灾害成灾面积仍处在增加阶段,同时近年来洪涝灾害成灾面积振荡幅度增大,即某些年份可能会出现大灾,说明湖南省洪涝灾害强度加剧,频度增加。并进一步分析了洪涝灾害加剧的成因,提出相应减灾对策。

Analysis on the fluctuation of inundated area of flood disaster at multi-time scales based on empirical mode decomposition method-A case study from Hunan Province

Empirical mode decomposition(EMD)method was used to study the fluctuation of inundated area of flood disaster from 1949 to 2002 in Hunan Province.The results show that the inundated areas fluctuate with 3 time scales,quasi-3-year,quasi-8-year and quasi-22-year.The analysis on the contribution ratio of fluctuations at different time scales indicates that the contribution ratio of quasi-3-year cycle is the highest meaning that quasi-3-year oscillation is the most prominent.The oscillations at different time-scales show that the amplitude of the fluctuation of inundated area has increased in recent years,and the great flood disaster maybe come forth in some years.The trends of oscillation at different time-scales suggest that the inundated area of flood disaster in Hunan Province be still in the period of increasing.The cause of the increase of frequency and intensity of flood disaster is further analyzed and some countermeasures are advanced to some extent.