Risk Assessment Of Major Meteorological Disasters During Apple Growth Period In Hedong Region Of Gansu Province

The Hedong area of Gansu is one of the important producing areas of apples in China.The area has a variety of climate types and complex terrain.Apples are an important source of income for farmers.In this study,the area with more apple production and complete data in the Hedong area was selected as the research area,and the main meteorological disasters facing apples—drought and spring frost were the research objects.This paper is based on the daily temperature and precipitation data of the National Meteorological Data Center from 1981 to 2019,the minimum temperature of 0cm at the site,and the statistical data of the Gansu Rural Yearbook from 1991 to 2013.Through the analysis of the hazard factors of the apple growing period Comprehensive assessment of the risk of frost and drought during the apple growth period from 1981 to 2019.turn out:(1)The maximum temperature,minimum temperature and average temperature in the main apple growing areas in Hedong showed a significant increase trend from1981 to 2019(P<0.05).The maximum temperature increase was the largest,the minimum temperature increased the least,and precipitation changes were not significant.The effective accumulated temperature of ≥5℃ and ≥10℃ showed that the initial date was earlier,the end date was delayed,and the duration increased,which led to a significant increase in the regional effective accumulated temperature.Compared to before 2000,the last frost days on the Longzhong Plateau and Longnan in the study area have been advanced after 2000,but the last frost days on the Longdong Plateau have been delayed.(2)In the study area,during different growth periods,different grades of frost have differences in spatial distribution,but generally the frequency and severity of frost are relatively high in areas with higher latitude or altitude.The area where droughts occurred frequently during the apple flowering,young fruit,and fruit swelling periods was located in the Xifeng to Jingning area,and drought events occurred in Xihe,Chengxian,Huixian and Liangdang areas during the mature period.The spatial distribution of the areas with longer droughts during the flowering and young fruit periods was more consistent,and the areas with longer droughts during the swelling and mature periods were also more consistent.The drought intensity is the largest in the fruit expansion period,followed by the young fruit period,the mature period and the flowering period.(3)The areas where apples are at greater risk of spring frost are located in the western part of the study area,the junction area of Longdong Plateau and Longdong Plateau,and the northern area of Longdong Plateau.The areas with lower spring frost risk are the southeast of Longdong Plateau and the area south of Qingshui and Jingning,Tongwei.(4)The areas with higher risk of apple drought are located in the northeast and southwest of Longdong Plateau.The study area is in the west of Longzhong Plateau,Jingning,Qin’an,Zhangjiachuan and Maiji.Areas with lower drought risk are located in the north,east,west,middle,and east of the Longdong Plateau,south of Maiji,and the Qinzhou District,Gangu,Tongwei,Qingshui and Zhuanglang areas.(5)The weight of spring frost in the main meteorological disasters of apples in the study area is greater than that of drought.The low comprehensive risk area is located in the Longnan part of the study area.The second low risk area is mainly located in the area from Zhenyuan to Heshui on the Longdong Plateau.There are many counties(districts)with higher risk in the Middle Plateau.The second-highest risk areas are located in three areas,from east to west,namely,the east of Huan County-the north of Huachi,Zhuanglang-Jingchuan and Zhangxian-Qin’an area.