新疆1950～1997年洪旱灾害的统计与分形特征分析

Statistical and fractal features of the flood and drought disasters in Xinjiang from 1950 to 1997

基于新疆1950～1997年的洪旱灾害统计资料,运用一般统计学方法与分形理论分析了新疆这段时期内相应的洪旱灾害特征。分析发现,20世纪80代年以来新疆洪旱灾害呈急剧扩大的态势,20世纪80年代和90年代与50年代相比,洪水与干旱灾害成灾面积都增大了约6～7倍;1950～1997年新疆洪旱灾害时间序列具有明显的分形特征,相应的饱和分维数分别为d=2.9733与d=3.6921,饱和关联维数对应的嵌入空间的最小维数为9。

Located in inland and far from oceans, Xinjiang is well known for its arid climate. Natural disasters occur frequently in this region. The most serious natural disaster here is droughts characterized by the vast effected area, long duration, and serious spring drought. Although Xinjiang is famous for its extensive desert and little rainfall, the flood calamities also occur here every year. Frequently occurred natural disasters, especially droughts and floods have damaged lots of properties and lives in the past decades in this region. In recent decades, there is a magnifying trend of the drought and flood calamities in this region, which is concordant with that occurring in China and in the world. Many researchers have paid their special attention to this phenomenon. Some important progresses have been gained on the researches of the general features of the flood and drought disasters occurring in Xinjiang. However, the statistical and fractal features of the timeseries of flood and drought disasters are unknown at present. Therefore, the aim of this paper is to examine the statistical and fractal characteristics of the timeseries, based on some statistical data on the effects of flood and drought disasters occurred in Xinjiang from 1950 to 1997. The results show that the temporal series of the flood and drought disasters have the fractal features with the fractal dimensions D2 being 3.75 for flood disasters and 3.65 for droughts, respectively. The obtained conclusions will be a scientific basis for the flood and drought disasters mitigation in Xinjiang.