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我国是一个干旱及旱灾频繁发生的国家,近年来干旱已成为影响我国社会经济可持续发展的重要制约因素。文中应用经验模态分解(EMD)方法分析了1950-2006年全国干旱灾害受灾面积波动情况。结果表明:(1)干旱灾害受灾面积存在准3年、准8.5年、准14年左右特征时间尺度的周期性波动;(2)各时间尺度的周期性振荡的贡献率中以准3年时间尺度的受灾面积振荡的贡献最大,说明干旱灾害受灾面积波动以准3年时间尺度为主;(3)从各时间尺度的振荡来看,大致分三个阶段,80年代中期以前,干旱灾害受灾面积的波动频率较慢,周期长,振幅大;80年代中期以后,波动频率变快,周期缩短,振幅减小;而90年代中期之后,振幅又有所增加。从各时间尺度振荡的趋势看,干旱灾害受灾面积仍处在增加阶段;而且近年来干旱灾害受灾面积振荡的幅度增大,说明干旱灾害强度加剧,频度增加。因此,应认识和了解旱灾发生和发展规律,并进行有效的防治,尽可能减小旱灾对社会经济发展造成的损失。
Our country is a country where droughts and drought frequently occur. In recent years, drought has become an important constraint on the sustainable social and economic development in our country. Empirical mode decomposition (EMD) method was used to analyze the fluctuation area affected by drought disaster in China from 1950 to 2006. The results show that: (1) The affected areas of drought disasters have cyclical fluctuations on the characteristic time scales of quasi 3 years, quasi-8.5 years and quasi-14 years; (2) The contribution rate of periodic oscillations on each time scale is 3 years The scale of the affected area of the largest contribution to the oscillation, indicating that the area affected by drought disasters, fluctuations in the quasi-three-year time scale based; (3) from the time scale of the oscillation point of view, roughly divided into three stages before the mid- The area fluctuated more slowly, with longer period and larger amplitude. After the mid-1980s, the frequency of fluctuation became faster, the period shortened and the amplitude decreased. After the mid-1990s, the amplitude increased again. Judging from the trend of oscillation at each time scale, the affected area of drought disaster is still on the increase stage. In addition, the amplitude of the area affected by drought disaster has increased in recent years, which indicates that the intensity of drought disaster is increasing and the frequency is increasing. Therefore, the occurrence and development of drought should be recognized and understood, and effective prevention and control should be implemented to minimize the damage caused by drought to the social and economic development.