Risk Assessment And Defense Planning Of Lightning Disaster In Inner Mongolia

With the rapid development of China's modernization construction,the damage caused by lightning disasters has a greater impact on various undertakings,and the public has put forward higher requirements for lightning protection and disaster reduction.According to incomplete statistics,China's annual average number of casualties caused by lightning disasters is about 1000 people,and the property loss is about 100 million yuan,while the direct economic loss caused by lightning in Inner Mongolia Autonomous Region in recent 15 years is as high as 175 million yuan.Therefore,comprehensive understanding and evaluation of lightning disaster risk level in Inner Mongolia Autonomous Region is not only an important basis for risk control,but also a theoretical basis for risk management decision-making.However,the current research mainly takes the League City or county as the smallest evaluation unit for lightning disaster risk assessment,and the actual situation is that there are still great differences in the disaster causing factors and disaster bearing bodies within the scope of each league city and county,so it is urgent to carry out refined scale lightning disaster risk assessment.According to the theory of natural disaster risk and technical guide of lightning disaster risk division,this paper constructs the risk assessment model of lightning disaster in Inner Mongolia.The Inner Mongolia area is divided into 4.7×10~4 5km×5km grids,and the Entropy-TOPSIS method is used to evaluate the risk of lightning disaster in Inner Mongolia.The planning countermeasures and suggestions are put forward for the work of lightning protection and mitigation in Inner Mongolia.Firstly,through the statistical analysis of the data collected by the lightning location instrument in Inner Mongolia from 2014 to 2018,the results show that the average annual number of ground flashes in Inner Mongolia is 292545.8,of which the negative ground flashover is 246364.6,accounting for 84.21%of the total,and positive ground flashes of 46179.4,accounting for 15.79%of the total ground flashes.The frequency of ground flashes is the highest from June to August every year,accounting for 81.94%of the total number of ground flashes in the whole year.Among them,July is the month with the highest number of ground flashes,and it gradually decreases from August.The lightning activity mainly concentrated from 12:00to 24:00 p.m.,less lightning activity occurred from 1:00 to 11:00,and the peak of lightning activity was 13:00 to 18:00.The magnitude of ground flash intensity mainly concentrated between 10-50k A,accounting for 77.46%of the total ground flash,of which the frequency of ground flash intensity is the most frequent in the range of 20-30k A,accounting for 28.65%of the total ground flash.Secondly,the statistical results of lightning disasters in 2008 to 2018show that the distribution of monthly variation of lightning disasters is unimodal.The number of lightning disasters,the number of casualties and the peak value of direct economic losses all appear in June.The lightning disasters mainly occur in June to August in summer,with a total of 228lightning disasters,accounting for 84.44%of the total number.According to the analysis of the disaster situation in League City,31 and 25 lightning disasters occurred in Horqin district of Tongliao City and Oroqen Autonomous Banner of Hulunbuir City respectively,which belong to high frequency lightning disaster area;Alxa Left Banner,Siziwang Banner,Sunit Right Banner and New Barag Left banner are medium frequency lightning disaster area;other areas are low frequency lightning disaster area.Thirdly,the evaluation factors are selected from the risk of disaster factors,the exposure of disaster bearing body and the vulnerability of disaster bearing body,and the lightning disaster risk evaluation model is constructed.Taking the 5km×5km massive spatial grid data as the evaluation unit,the Entropy-TOPSIS method and Arc GIS software are used to evaluate and grade the lightning disaster risk in Inner Mongolia.The results show that the high-risk areas are mainly located in the central and western regions of Inner Mongolia where the population and GDP density are relatively concentrated,and the disaster causing factors such as lightning density and intensity are relatively strong,and the cities and towns of Chifeng City,Tongliao City,Ulanhot City,Alxa Left Banner,Xilinhot City and Hailar District are located,accounting for 17.38%of the area of Inner Mongolia Autonomous Region;the middle risk areas of lightning disaster are mainly the middle risk areas The areas around the urban circle of Hohhot City,Baotou City,Ordos City and Ulanqab City with low population density but high lightning density and intensity,as well as the areas of Arhorqin Banner,New Barag Left Banner,Bairin Left Banner,Sunit Right Banner and Jalaid Banner in the northeast,account for 23.65%;other areas have low lightning disaster risk,such as Alxa League in the west of Inner Mongolia and Hulunbuir City in the northeast In the northern part of Inner Mongolia and Xilingol League,the risk of lightning disaster is the lowest,which accounts for 58.97%of the area of Inner Mongolia.At the same time,comparing the risk assessment results with the historical lightning disasters in Inner Mongolia from 2008 to 2018,we can see that 87.77%of the lightning disasters are in the areas with medium or above lightning disaster risk.Therefore,the risk assessment results of this paper are basically consistent with the actual disasters.Finally,based on the risk assessment of lightning disaster,the risk zoning of lightning disaster in the study area and its causes are analyzed,and the comprehensive analysis of the risk of lightning disaster factors,the exposure and vulnerability of the disaster bearing body and the characteristics of the disaster situation are made,and the countermeasures and suggestions for lightning protection planning and disaster reduction are put forward.Among them,the high-risk areas are mainly urban areas with high population and GDP density.Therefore,this paper takes Hohhot,an economically developed urban area with high risk of lightning disaster in Inner Mongolia,as an example,according to the classification of lightning protection of buildings and the distribution characteristics of lightning density,the suitable range of building height and the planning suggestions for the classification of lightning protection of buildings are put forward;For medium and low-risk areas,mainly around the town and other remote areas,this paper also puts forward targeted countermeasures and suggestions for rural and animal husbandry areas.