The Characteristics Of Drought Disasters In North China During The Ming And Qing Dynasty

Regional drought becomes more and more severity under the background of global warming. The North China belongs to the arid and semi-arid regions.This problem of drought characteristics becomes more and more obvious in the North China has attract experts and scholars’attention. The research of historical drought characteristics for understanding future droughts in the region, as well as the development of disaster prevention is of important significance to modern drought. This article fully absorbed the results of previous spatial and temporal evolution on the drought disaster events in historical sequence, based on the record drought in North China during the Ming and Qing dynasties, establish drought disaster sequences in Ming and Qing dynasties in North Chiaa. A variety of statistical methods, such as EEMD, EOF, REOF and other methods is used to analysis the temporal and spatial characteristics. Finally, based on the historical data, BG segmentation algorithm, Mann-Kendall test and polynomial fitting methods are used to analyze the drought disaster in North China to provide an important reference for the study of drought conditions. The results show that:(1) In North China in the Ming and Qing dynasties, there are general drought 245 times, once every 1.8 years on average; Big drought 123 times, once every 3.6 years on average; severe drought 44 times, once every ten years on average.20 years scale drought in the North China in the Ming and Qing dynasties rise after falling first which twist in Qianlong. The period is named the Qianlong 35 year to Qianlong 54 year. Before that time, the frequency of drought disaster decreased slowly. But after Qianlong 54 year, the frequency of drought disaster increased rapidly. In different time scales, the drought disasters in North China in Ming and Qing dynasties exists three scales. They are interannual periods of 3.0a (IMF1) and 6.1a (IMF2), decadal periods of 12.7a (IMF3),27.4a (IMF4),48.4a (IMF5) and centennial-scale periods of 151.1a (MF6), 214.5a (IMF7). Interannual periods of 3.0a,6.1a, decadal periods of 12.7a,27.4a and centennial-scale period of 151.1a are falling more than 95%. They are the most significant component which contained the largest component of the physical meaning.(2) Drought disasters occur most frequently in the west and east of the North China, Such as Datong, Taiyuan, Linfen, Changzhi, Dezhou and Jinan. Drought disasters occur little in the south of North China, such as Luoyang, Xinyang regions. Overall, the drought disasters occur more in north than in south. The intensity of drought disasters in North China is different. The highest intensity drought disaster is Dezhou, Jinan, Heze, Linyi, Laiyang, which is in the east of the North China. The lowest intensity drought disaster is Tianjin in northeastern of North China and Handan, Shijianzhuang, Cangzhou, which is in the middle of North China. Overall, the drought intensity distribution is high in southeastern and low in the northwest. By EOF analysis, the first typical field shows that drought disaster in North China in the Ming and Qing dynasties represented the same type. The change of drought disaster in the region are coincident, performanced the same more or less characteristics. The other typical field performanced the region difference in the whole field, such as the north-south reverse, east-west reverse, north south-east west reverse and central-around reverse. REOF analysis concluded that North China can be divided into six extraordinarily sensitive areas, named the middle-east area, west area, north area, east area, north-east area and south-east area.(3) The number of drought counties in North China during Ming and Qing dynasties is declining. Through the MK test and BG segmentation algorithm, there is one mutation in Zhengde period. It means that in the total time, the number of drought-countries can be divided into two sections, the previous of drought disasters are larger and the later drought disasters are smaller. There were multiple continuous drought periods in Ming and Qing dynasties. Since 1470a, there were five influential events uprising in major drought event. It is in addition to the events of Tai-ping has little relationship with the drought. The remaining four had a significance relationship with drought disaster in North China.