| In recent decades,with the acceleration of global warming,strong convective weather such as rainstorm,gale,and hail have frequently occurred all over the world,causing major human casualties and economic losses.The strong convective weather with strong bursts and strong destructive power have been the main disastrous weather in the world.People gradually realized the importance of conducting disaster risk prevention research and avoiding the strong convective weather disaster risk for the sustainable development of social.In the past,the risk study of a single strong convective weather disaster has been difficult to cope with the current situation of multiple strong convective weather disasters.It is of great significance to mitigate disaster risk by comprehensive risk assessment studies focusing on multiple strong convective weather disasters.Due to the influence of Meso-small scale weather systems,topography,and geographical locations,strong convective weather such as rainstorm,gale,and hail frequently occurred in Chongqing.Moreover,Chongqing is a municipality with the largest proportion of agriculture and the largest population in China.The annual economic losses caused by strong convective weather amount to several hundred million yuan.Facing the current situation of strong convective weather disaster,it is particularly important to conduct quantitative assessment of the comprehensive risk of strong convective weather disaster in Chongqing.Based on the strong convective weather data of 34 national meteorological stations in Chongqing form 1981 to 2010 and the socio-economic data of 38 counties in Chongqing,using the mathematical statistics method and the inverse distance weight interpolation method to obtain the spatial-temporal distribution characteristics and causes of the strong convective weather in Chongqing.According to the index selection principle,constructing a comprehensive risk assessment index system for strong convective weather disaster,which include the hazards,exposure,sensitivity and coping capacity.The index weight adopt the synthetic method,which integrated entropy method and analytic hierarchyprocess.Based on the fuzzy matter element evaluation method to realize the quantitative determination about comprehensive hazard,exposure,sensitivity,coping capacity,comprehensive vulnerability and comprehensive risk of strong convective weather disaster in Chongqing.The following are the main conclusions of this research:(1)The temporal and spatial distribution characteristics of strong convective weather in Chongqing(1)The rainstorm days changed significantly and showed a remarkable unimodal feature during the year.May to September was a frequent period of rainstorm and reached its peak in July.Most rainstorms occur in summer,less occur in spring and autumn,and there is no rainstorm in winter.The inter-monthly changes of rainstorm days are closely related to the movement of subtropical high.There are three high-incidence areas about rainstorm: the North-East of Chongqing such as Kaizhou District,the South-East of Chongqing such as Youyang County and the West of Chongqing such as Beibei District.The regional variability in average annual rainstorm days are closely related to geographical location,weather system and its movement,topography and so on.(2)The gale in Chongqing mainly occurred in March to September,and the distribution ratio during the year showed a clear bimodal structure.July to August,the gale were the most,and more than 4-5 months,especially peak appeared in August.Most of the gale occurred in summer,followed by spring,autumn and winter were less occurred.The seasonal evolution of gale is affected by factors such as geographical location and circulation background.High frequency zone of gale is located in Wuxi County in the North-East of Chongqing.The terrain factors have a greater impact on the frequency of gale in Chongqing.(3)The thunderstorm in Chongqing mainly occurred in April to August,and reached its peak in July.Chongqing has the most thunderstorms in summer,followed by spring,and fewer thunderstorms in autumn and winter.The inter-monthly variation of thunderstorm days are closely related to the amount of precipitation.The thunderstorm days in Chongqing showed the distribution characteristics as following: western is less than eastern and northern is less than southern.The County in the South-East of Chongqing such as Youyang and Xiushan,which have a high frequency in thunderstorms.The spatial distribution characteristics of thunderstorm days in Chongqing are closely related to the terrain and water vapor supply paths.(4)The hail in Chongqing mainly appeared in March to August and showed a significant bimodal characteristic.The main peak appeared in April and May,Second peakappeared in July and August,especially peak appeared in April.Most hail occurred in the afternoon or midnight of spring and summer,less hail occurred in autumn and winter.The inter-monthly variation of hail in Chongqing is closely related to the seasonal changes in ambient temperature and updraft.The annual average hail days in Chongqing showed a trend of decreasing gradually from southeast to midwest.The spatial distribution of annual average hail days in Chongqing is closely related to topographic conditions.(2)The comprehensive hazard level of strong convective weather disaster in Chongqing is lower as a wholeIn 38 counties of Chongqing,there are 3 counties belonging to highest hazard level,7.89%of the total;12 counties belonging to higher hazard level,31.58%of the total;23counties belonging to lower and lowest hazard level,60.53 % of the total.From the perspective of spatial distribution,highest and higher hazard counties are mainly distributed in North-East and South-East of Chongqing.The South counties in the North-East,the North counties in the South-East and most Mid-West regions with lower hazard and lowest hazard levels.The combination of high rainstorm hazard level and high gale hazard level is the main reason why the entirety high hazard level in the North-East.The combination of high thunderstorm hazard level and high hail hazard level is the main reason why the entirety high hazard level in the South-East.The lower or lowest hazard levels are mainly due to the lower or lowest level of disastrous weather such as rainstorm,gale,thunderstorm,and hail.(3)The overall comprehensive vulnerability of strong convective weather disaster in Chongqing is higherIn 38 counties of Chongqing,there are 5 counties belonging to highest vulnerability level,13.16%of the total,17 counties belonging to higher vulnerability level,44.74%of the total,16 counties belonging to lower and lowest vulnerability level,42.10%of the total.From the perspective of spatial distribution,the North-East region of Chongqing with the highest overall vulnerability,followed by the area around the main city,but the overall vulnerability of South-East region is higher,the overall vulnerability of the main city is lower.In general,the counties of highest and higher vulnerability levels are connected in the form of “people”,lower and lowest vulnerability counties concentrated in the main city area,and Some of the lower vulnerable grade counties are scattered in marginal areas.The comprehensive vulnerability of the strong convective weather disaster is related to the composition of vulnerability,such as exposure,sensitivity,coping capacity.For counties with the same level of vulnerability,there are differences in the composition of the threeelements of vulnerability.(4)The overall risk of strong convective weather disaster in Chongqing is relatively lowIn 38 counties of Chongqing,there are 6 counties belonging to highest risk level,15.79 % of the total,8 counties belonging to higher risk level,21.05 % of the total,12 counties belonging to lower risk level,31.58%of the total,12 counties belonging to lowest risk level,31.58%of the total.From the perspective of spatial distribution,it showed the high risk of the North-East wing and the South-East wing,but the low risk within the“one-hour economic circle”.The North-East region of Chongqing with a high magnitude center in Kaizhou district has the highest risk,and exceeds the South-East region.There are two low-risk areas of strong convective weather disaster: one is the main city area;the other is the north of the South-East of Chongqing.The high risk level of strong convective weather disaster in Chongqing is caused by higher or highest hazard overlay higher or highest vulnerability,and the low risk level of strong convective weather disaster in Chongqing is caused by lower or lowest hazard overlay lower or lowest vulnerability.The strong convective weather disaster have a large differences in the causes of higher risk levels and lower risk levels. |
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