Risk Assessment Of Cold Spring Disasters In The Main Winter Wheat Producing Areas In Northern China

As a typical meteorological disaster,the late spring cold has affected the yield and quality of winter wheat to a certain extent under the background of climate warming,and caused harm to the food security of China.Based on the data of 103 meteorological stations in the main winter wheat producing areas in northern China from 1961 to 2020,this study calculated the occurrence frequency and intensity of late spring cold.The occurrence intensity of late spring cold in different growth periods was calculated and used as the risk index in the risk assessment model;at the same time,the winter wheat production efficiency index,production specialization index,farmland production potential index,and terrain relief index were selected as the vulnerability index,combining with the cultivated land index,building the disaster risk assessment model of the late spring cold in the main winter wheat producing areas in northern China,and studied the disaster risk of the late spring cold in the main winter wheat producing areas in northern China.The results show:(1)From 1991 to 2020,the total number of cold spring disasters and the number of mild,moderate and severe cold springs showed an upward trend,but it was not significant.The number of cold spring disasters decreased first and then increased in different decades.From the perspective of spatial distribution,the occurrence frequency in the eastern region was higher than those in the western region;the central part of Shandong Province had fewer occurrences of late spring cold due to the influence of topography.(2)Judging from the interannual variation characteristics,the cumulative K value of severe late spring cold disaster at jointing-heading stage,the cumulative K value of late spring cold disaster after heading stage,and the cumulative K value of mild,severe and severe late spring cold disaster after heading stage showed a significant upward trend(P < 0.05),the changes in the cumulative K value of late spring cold in other growth periods were not significant.From the perspective of spatial distribution,the cumulative K value of winter wheat in the key growth period and different growth periods,as well as the cumulative K value of mild and moderate inverted cold decreased gradually from east to west and from north to south.The cumulative K value of winter wheat in the key growth period,turning green-joining period,and jointing-heading period showed a distribution trend of low in the middle and high in the four weeks.After heading,the accumulated K value of severe late spring cold showed a decreasing trend from northeast to southwest.(3)The distribution characteristics of the spring cold disaster in the main winter wheat producing areas in northern China showed the distribution characteristics of high in the east and low in the west,among which the sub-high-risk area > the sub-low-risk area > the medium-risk area > the low-risk area > high-risk area.The high-risk areas were mainly distributed in the central part of Henan Province,the southern part of Henan Province,the northern part of Shandong Province,Tianjin Municipality,and parts of Jiangsu Province;the sub-high-risk areas were mainly located in Henan Province and Shandong Province;the medium-risk areas were mainly distributed in Henan Province,Anhui Province and Jiangsu Province;and the low-risk areas and sub-low risk areas were mainly found in Gansu Province,Shaanxi Province and Shanxi Province.