| Faced with global changes and increased disasters,it is important to study climate change during the historical period.Disaster research in the historical period is one of the important research contents of the two major international research programs in the Past Global Change(PAGES)and the Climate Variability and Predictability Program(CLIVAR).This paper collected the literature records of the drought and flood and low temperature disasters in South China from 1644 to 1911,established the historical database of drought and flood history and low-temperature disasters,and explored the situation of drought and flood and cold and warm in South China from 1644 to 1911.And its distribution and change in time and space were analyzed by multi-data source,multi-method and multi-scale,the possible influence factors of drought and flood in South China were also analyzed.The characteristics of mass disaster in late Qing Dynasty are revealed.The areas with frequent occurrence of disasters in Southern China has been discussed in this paper.It can provide reference for disaster prevention and reduction in Southern China.The main conclusions of the study are:(1)Count the frequency of drought and flood disasters.In Southern China,the frequency of flood and drought disasters in the east is more than that in the west.The highest frequency areas of flood are near the Pearl River estuary in western Guangdong and Chaozhou prefecture.For drought,the frequency is high in Chaozhou prefecture,near the Pearl River estuary and Hainan island.The temporal and spatial differentiation and evolution characteristics of drought and flood in South China were explored by EOF.The four main spatial distributions are the same type of the region,the northeast-southwest reverse type,the negative-positive-negative distribution of the northwest-southeast direction,and negative in the middle.The change of drought and flood disaster in South China is divided into five climate sensitive areas by REOF analysis,which is the southeastern region,the southwest region,the northwest region and the northeast region,and the south-central region.(2)The region drought and flood index sequence from 1644-1911has been established,the region had a total of 98 years of flood,78 years of drought,79 years of normal.It was found that the flood frequency was higher than the drought frequency in general,and the frequency of drought increased in the middle Qing Dynasty and decline in the late Qing Dynasty,and the occurrence of floods is the opposite.the mutation characteristics of drought and flood grade sequence was carried out by sliding T test.On the 10-year scale,the sliding t statistic has five abrupt points or abrupt intervals.which is positive in 1690,1753-1757,1863-1866.In this time the climate trend from flooding to drought-it is negative in 1669,1883-1887,in this time the trend from dry to waterlogging.On the 30-year scale,the sliding t statistic has one abrupt points which is passed 0.05 significant level test,this abrupt point is positive.Indicating that in the 30a time scale,there is a obvious mutation from dry to waterlogging in 1671-1674.In this paper,we studied the periodic characteristics of drought and flood in South China by using the empirical empirical modal decomposition CEEMD method.There are three types of droughts and floods,which are the interannual periods of 2.5a and interdecadal periods of 9a,11a,18a,38a and 69a,and century periods of 125a.(3)The response of the drought and flood changes to solar activities,the East Asian summer monsoon changes and the South Asian summer monsoon changes were discussed by using the crossed wavelet.It was found that there were significant responses between the change of drought and flood in South China and the 3 impact factors.There are strong cohesive resonance period of 8-14a scale,10-16a scale and 2-6a scale between the relative number of sunspots series and drought and flood index series of South China,the the relative number of sunspots series ahead of drought and flood index series around one cycle.There are strong cohesive resonance period of 30-48a scale,4-8a scale,and 64-96a scale between the East Asian monsoon index series and the South China drought and flood index series,the East Asian monsoon index series ahead of the drought and flood index series around half a cycle.There are strong cohesive resonance period of 4-11 a,16-56a and other time scales between the South Asian monsoon index series and the South China drought and flood index series.(4)Collected and sorted out the records of snowstorm,frozen,frost and cold records in South China from 1644 to 1911.The frequency of low temperature chilling in the eastern part is higher than that in the west.Guangzhou Prefecture,Zhaoqing Prefecture and the eastern Chaozhou Prefecture are high frequency areas of low temperature chilling injury,which are also high frequency areas of drought and flood.Early Qing Dynasty and late Qing Dynasty is frequent occurrence of low temperature chilling injury,the late Qing is particularly serious.By arranging the records of the time of low temperature chilling injury in ancient books,the characteristics of seasonal of low temperature disaster has been discussed.The high season of low temperature chilling injury is winter,followed by spring.The low temperature chilling injury in South China has the period of 6a,10a,17a,29a,54a,130a,and the period of 29a is the first main cycle.This paper explores the frequency of low temperature chilling injury,flood and drought in the county level every 30 years,the counties where floods occur and the counties where drought disasters occur.It is found that low temperature chilling injury has significant correlation with drought.And found that drought,flood and low temperature chilling injury has a similar trend,three kinds of disasters increased,significantly in the late Qing Dynasty.This paper reveals the characteristics of the disaster in South China during the late Qing Dynasty,and speculated that may be a combination influence by anomaly of celestial motion,environmental damage and social crisis. |
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