| Yunnan Province is located in the southwest border of China.Affected by the topography and monsoon,the dry and wet seasons are distinct.The spatial and temporal distribution of precipitation is uneven,so it is prone to droughts,floods and other meteorological disasters.In addition,Yunnan Province is located at the junction of Eurasian plate and Indian Ocean plate,with strong crustal movement and complex geological structure,so it is prone to earthquakes.The occurrence of earthquake,drought and flood has a great impact on human production and life.Therefore,this paper explores the temporal and spatial characteristics and symmetric structures of earthquakes,droughts and floods in different regions of Yunnan Province from the annual scale and the seasonal scale respectively,and discusses the relationship between three kinds of disasters and sunspots,ENSO from different scales,so as to form a risk management mode which takes disaster risk as the main line,from the outside to the inside,step by step,to realize the fine docking of macro and micro.In this paper,we use the standardized precipitation evapotranspiration index to judge the drought and flood events in Yunnan Province,and use the symmetric structure to analyze the time-space symmetric structure of earthquake,drought andflood,and use Satcan to identify the time-space clustering area of the dominant risk,and use the cold hot spot analysis to identify the spatial characteristics of the recessive risk,and use the pole symmetric mode decomposition method to analyze the trend characteristics of the drought and flood climate background,and use wavelet transform to analyze the spatial characteristics of the recessive risk.The relationship between earthquake-drought-flood and sunspot and ENSO is discussed.The main conclusions are as follows:(1)According to the temporal and spatial distribution of historical earthquakes in Yunnan Province,on the annual scale,earthquakes with Ms?5.5 are mainly concentrated in the 1970s,and the seismicity is relatively frequent in the past 10 years.In addition,the frequency of earthquake occurrence shows obvious regional difference:Western Yunnan>Central Yunnan>Eastern Yunnan.In the aspect of monthly variation,the frequency of earthquakes with Ms?5.5 in Yunnan Province is higher in the summer half year.In terms of daily variation,the earthquakes in Yunnan Province mainly occurred at night.(2)From the perspective of time-space symmetry structure and stability of earthquakes in Yunnan Province,in terms of time,on the annual scale,there is a high probability of occurrence of earthquakes with Ms?5.5 in 2022,followed by 2021;in western Yunnan,there is a high probability of occurrence of earthquakes with Ms?5.5 in 2020,followed by 2022.On the seasonal scale,Earthquake is likely to occur with Ms?5.5 in 2021,followed by 2022.Spatially,the next earthquake in Yunnan Province may occur in the northern region.(3)From the perspective of climate background,the temperature changes in the stage of "low fluctuation-rapidly rise-warming stagnation ",and the spatial distribution characteristics of "low in the north and high in the South".The annual precipitation shows the stage of "low fluctuation-slowly decline".The spatial difference of annual precipitation is large.From the index value of drought and flood,Yunnan Province as a whole shows the obvious phenomenon of "alternation of drought and flood" and the spatial difference is large,and the trend of drought and flood in each region is inconsistent.(4)From the perspective of spatiotemporal symmetric structure of drought and flood in Yunnan Province,on the annual scale,the possibility of flood in 2023 is great,followed by 2020;the possibility of flood in 2020 in central Yunnan is great,followed by 2021;the possibility of flood in 2022 in eastern Yunnan is great,followed by 2021.On the seasonal scale,in spring,there is a high probability of occurrence of flood in central Yunnan in 2020,followed by 2022;in summer,there is a high probability of occurrence of flood in central Yunnan in 2022,followed by 2020;in summer,there is a high probability of occurrence of flood in eastern Yunnan in 2020,followed by 2021;in winter,there is a high probability of occurrence of flood in the whole region in 2021,followed by 2022;in winter,there is a high probability of occurrence of flood in western Yunnan in 2021,followed by 2024;in winter,there is a high probability of occurrence of flood in central Yunnan in 2021.The possibility of flood in 2022 is higher,followed by 2022;in winter,the possibility of flood in 2022 is higher,followed by 2026.(5)According to the relationship between earthquakes and the number of sunspot,the earthquakes with Ms?5.5 mainly occurred in the decline stage of sunspot relative number.From the relationship between drought and flood index and sunspot relative number,on the annual scale,on the short period scale of 2-4a,the more sunspot relative number,the more flood.According to the relationship between earthquakes and ENSO,earthquakes usually occur in normal years and La Nina years,but they are not easy to occur in El Nino years.According to the relationship between drought and Flood Index and ENSO,on an annual scale,when the SST(sea surface temperature)in the East Pacific is abnormally high,floods are likely to occur in the West and east of Yunnan.When the SST in the Western Pacific is abnormally high,floods are easy to occur in Yunnan Province.In summer,on the small period scale of 2-4 years,when the SST in the East Pacific is abnormally high,Yunnan Province is prone to flood;on the large scale cycle of 8-16 years,when the SST in the East Pacific is abnormally high,Yunnan Province is prone to drought.At the same time,when the SST in the Western Pacific is abnormally high,Yunnan Province is prone to drought on the periodic scale of 2-4a and 8-16a.In winter,when the SST in El Ni(?)o 3 region is abnormally high,drought is easy to occur in all regions of Yunnan Province(except central Yunnan).At the same time,when the SST is abnormally high on the periodic scale of 2-4 years,all regions of Yunnan Province are prone to drought.(6)From the perspective of risk identification level,the dominant risk identification shows that the seismic risk concentration areas in Yunnan Province in recent 60 years are mainly located in the west and north regions,which coincide with the stability analysis results;the arid concentration areas have experienced the "northwest west"migration process.The flood concentrated area has experienced the migration process of"northwest west".Hidden risks identify that the central,eastern and northern areas of Yunnan Province are more likely to be affected,and are also the most likely places to have hidden risks.The catastrophic risk identification shows that the flood events occurred at the same time in Yunnan Province before the 1990s were mostly occurred.In recent years,the earthquake occurred with drought,which needs attention.(7)From the perspective of multi-level management mode,explicit risk identification mode mainly focuses on two stages:historical disaster risk identification and future disaster risk identification.The hidden risk management and control mode is mainly based on the previous two stages,aiming at the possible consequences of the hidden risk,to take certain control measures.The catastrophic risk management model proposes a multi-hazard risk system of "three stages,four levels,five forces,and six mechanisms" to maximize the effective connection between theory and practice,disaster response models and various policies and departments. |
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