Risk Assessment Of Major Meteorological Disasters In Flue-cured Tobacco Planting In Yux

Flue-cured tobacco represents one of the important cash crops in China.Yuxi city in Yunnan province is one of the highest quality core value areas in China,which is of great significance to ensure the cultivation,production and sound development of flue-cured tobacco.Yuxi flue-cured tobacco is sensitive to meteorological factors such as light,temperature and water.Nowadays,the climate has suffered great changes,thus causing frequent extreme disasters.As such,Yuxi flue-cured tobacco is often affected by various meteorological disasters,making local flue-cured tobacco cultivation a huge challenge.Therefore,to explore the main meteorological disaster risks of Yuxi flue-cured tobacco cultivation and to avoid or mitigate its possible losses,this paper analyses the spatial and temporal changes of drought,low temperature and chilling damage,overcast and rainy days as well as flooding occurred in Yuxi flue-cured tobacco cultivation based on meteorological data from 1990 to 2019,as well as fluecured tobacco cultivation area,production and other related socio-economic data in nine counties(districts)of Yuxi.Besides,the multi-disaster comprehensive risk assessment model was established.Then combining four factors:hazard of the causative factor,vulnerability of the hazard-bearing body,exposure and disaster prevention and mitigation capacity,the AHPCRITIC combination weighting method was used to calculate the index weights.The comprehensive risk assessment model of main meteorological disasters in Yuxi flue-cured tobacco planting was constructed by natural disaster risk index method and the risk zoning was carried out based on GIS platform.The research results are as follows.(1)This paper evaluates the level and spatial distribution characteristics of comprehensive risk factors during the growth period of flue-cured tobacco.There are differences in the spatial and temporal changes of each disaster.Drought during transplanting and root extension:light,heavy and exceptional drought coverage becomes wider over time.The rate of widening:exceptional drought>heavy drought>light drought.The climate tendency rate of exceptional drought is 6.92/10a.Medium drought coverage decreases over time.Northeast areas are mainly in medium and exceptional drought,while southwest areas are mostly in light drought.Drought during fast-growing Stage:medium and exceptional drought coverage increases over time at a rate of 2.82/10a and 2.79/10a,light and heavy drought decreases over time at a rate of 3.53/10a and 3.63/10a.Light droughts dominate in the eastern region,whereas light and moderate droughts in the western region.Drought coverage in both periods:light drought>moderate drought>heavy drought>exceptional drought.The overall coverage of low-temperature chilling damage is decreasing.Before 2000,the lethal low-temperature chilling damage covered the largest area,while after 2000,the barrier type covered the most.Low-temperature chilling damage frequency:barrier type>lethal type>delayed type.The eastern part is dominated by the barrier type and the western part by the lethal type;the barrier type has the greatest impact on Yuxi as a whole.The coverage of overcast and rainy days:light>medium>heavy,the coverage of three levels decreases with time.The fastest rate of decreasing was heavy level:7.12/10a.The medium level increased and decreased with mutation for many times;frequency of occurrence:light>medium>heavy;the frequency of all levels increases from southwest to northeast.The coverage of precipitation and the frequency of heavy and torrential rain from June to August are both:heavy>medium>light,with light and medium level rising with time.The precipitation in the middle and south of Yuxi is mainly between 300-450mm,and the precipitation in the northwest and northeast is mainly greater than 450mm.The frequency of heavy and torrential rain was mainly between 3-4 times in the west,and more than 5 times in the east.The coverage of precipitation and the frequency of heavy and torrential rain both had a mutation near 2010.The eastern area is the most frequent area of heavy rainfall and flooding.(2)High-risk areas(0.63-0.80)for drought are in Chengjiang and eastern Xinping,while low-risk areas(0.22-0.34)are in Jiangchuan,Yimen and southeastern Eshan;high-risk areas(0.70-0.93)for low-temperature chilling damage are in Chengjiang and Tonghai,while low-risk areas(0.00-0.21)are in Yuanjiang and southeastern Xinping;high-risk areas(0.76-1.00)for overcast and rainy days are in the whole eastern region,while low-risk areas(0.00-0.21)are in Yuanjiang;high-risk areas(0.66-0.90)for heavy rain and flooding are mainly in eastern Yuxi,while low-risk areas(0.00-0.19)are distributed in Yuanjiang.The spatial characteristics of the combined multi-hazard hazard increase from west to east,with the high-risk area(0.74-0.96)in Chengjiang and the low-risk area(0.22-0.35)in Yuanjiang,Yimen and Jiangchuan areas.Areas with high vulnerability(0.77-0.87)are in Xinping and Eshan,and the low vulnerability area(0.56-0.58)is in Yuanjiang.The high exposure zone(0.73-1.00)is in Jiangchuan and Tonghai as well as the low exposure zone(0.00-0.01)is in Xinping.Areas with high value disaster prevention and mitigation capacity(0.73-1.00)is in Tonghai and Hongta,while the low value zone is in Yuanjiang.(3)The comprehensive risk of major meteorological disasters in Yuxi flue-cured tobacco increased from southwest to northeast in space.The high-risk areas(0.61-0.76)mainly in Chengjiang;The second highest risk areas are in Xinping,Huining,Jiangchuan and the central area of Tonghai;The medium risk areas are located in the central region of Yuxi,including Hongta,Eshan,Tonghai,central Jiangchuan,and southern Xinping;The second low risk areas are in Yimen,the east and north of Yuanjiang,and the west of Hongta.The lowest risk areas(0.12-0.20)are in Yuanjiang and the middle of Yimen.