| From a worldwide perspective,China belongs to a region prone to meteorological disasters,especially in the context of global warming,China’s agricultural production will also face more risky challenges.Therefore,it is important to research the changing characteristics of agrometeorological hazards and the degree of impact on crop yield to improve the disaster prevention and mitigation capacity in the middle and lower reaches of Yangtze River.In this paper,we first analyzed the spatial and temporal variation characteristics of agrometeorological hazards in the middle and lower reaches of Yangtze River from 1985 to 2014 based on meteorological data crawled by Python,and then analyzed the spatial and temporal evolution of low temperature accumulation and heavy rainfall accumulation based on the observation data of meteorological stations,and finally explored the correlation magnitude of major agrometeorological hazards in the region based on disaster data and using gray correlation analysis on grain yield,rice yield and cotton yields.The main conclusions are as follows.(1)Based on the number of days of major agrometeorological disasters,in terms of interannual variation,the number of days of drought in six provinces in the middle and lower reaches of Yangtze River region showed an overall increasing trend,with the most obvious change in the rising trend of drought in Jiangsu Province and a relatively slow rising trend in Zhejiang Province.The trend of change in the number of days of heavy rainfall and flooding is not obvious,and except for Hubei Province in the slow decline,the rest of the provinces are slowly rising trend.The overall number of low temperature days showed a downward trend,and the most obvious downward trend in Jiangsu Province.The accumulation of heavy rainfall in the six provinces is only Hubei Province is a declining trend,the rest of the provinces as a whole are on the rise.The low-temperature accumulation temperature is rising except for Jiangsu Province,while the rest of the provinces show an obvious decreasing trend.In the spatial variation,the distribution of major agricultural weather hazards in the middle and lower reaches of the Yangtze River has obvious territoriality.Droughts are mainly distributed in the northern part of the middle and lower reaches of the Yangtze River,and the number of consecutive drought days is concentrated in 33.0～90.5d.Heavy rainfall and flooding are mainly concentrated in the central part of the middle and lower reaches of the Yangtze River,with the number of days of heavy rainfall concentrated in the range of 4.0-9.2d.Low temperatures are also concentrated in the northern part of the middle and lower reaches of the Yangtze River,with the number of consecutive low temperature days ranging from 98.0 to 148.6d.Heavy rainfall areas are concentrated in the central part of the middle and lower reaches of the Yangtze River,with cumulative precipitation in the range of 461.5～750.5 mm.The low temperature accumulation low value area is located in the northern part of the middle and lower reaches of Yangtze River,with accumulation temperature range of-348.9～-50.4℃.(2)Based on the frequency of major agricultural meteorological disasters,the overall frequency of drought,heavy rainfall and flooding,and low temperature in the middle and lower reaches of the Yangtze River exceeded the annual average for 16 years during 19852014,and the top five years were 1988,1996,1999,1995,and 2010 in order.The frequency of disasters in most regions in the middle and lower reaches of the Yangtze River is low temperature>heavy rainfall and flooding>drought,and only in Hubei Province,Anhui Province and individual cities in Jiangsu Province is low temperature>drought>heavy rainfall and flooding.(3)Based on the analysis of disaster data,it is found that the largest disaster-affected area in the middle and lower reaches of the Yangtze River during the 30-year period was 20,974 thousands of hectares in 1998,while the largest disaster-formative area occurred in 1991,reaching 10,870 thousands of hectares.Among the six provinces,Anhui Province had the highest percentage of drought and flood disasters,with 83%of the affected area and 87%of the disaster area.The larger values of drought,flood and low temperature freezing disaster-affected ratio and disaster-formative ratio in the six provinces from 1985 to 2014 were found in Hubei Province and Hunan Province,and the larger values of wind and hail disaster-affected ratio and disaster-formative ratio were found in Jiangsu Province and Hubei Province.(4)The effects of major meteorological disasters on crop yields were analyzed based on the gray correlation method,and the correlation series of total grain yield,rice yield,cotton yield and four major meteorological disasters were obtained.For total grain yield and rice yield,the provinces and types with the highest impact of disaster-affected ratio are the same:wind and hail disasters in Jiangsu,Anhui,and Hunan provinces,and flood disasters in Zhejiang,Jiangxi,and Hubei provinces,respectively;and the provinces and types that had the greatest impact on the disaster-formative ratio were the same,respectively:hail disaster in Jiangsu,Anhui,Hubei and Hunan,and flood disaster in Zhejiang and Jiangxi.As far as cotton production is concerned,the disaster-affected ratio has the greatest impact on it:wind and hail disasters in Jiangsu,Anhui,Hubei,and Hunan provinces,and floods in Zhejiang and Jiangxi provinces;the disaster-formative ratio has the highest impact on cotton production:wind and hail disasters in Jiangsu and Hubei provinces,and floods in Zhejiang,Anhui,Jiangxi,and Hunan provinces.In summary,agricultural production in China will face more challenges in the context of climate warming and the increased impact of extreme weather disasters.In terms of the impact of meteorological disasters on grain production in the middle and lower reaches of the Yangtze River,Jiangsu,Anhui,and Hunan provinces are most affected by wind and hail disasters,while Zhejiang,Jiangxi,and Hubei provinces are most affected by floods.Due to the different geographical locations and environments,there are differences in the weather hazards suffered by each region.For this reason,this paper suggests that agricultural facilities should be reasonably invested to mitigate the adverse effects of agricultural meteorological disasters on agricultural production,taking into account the magnitude of the disaster in each province. |
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