Risk Evaluation Of Apple Disasters Caused By Water Deficit And Surplus And The Insurance Product Research

Apple planting is an important forest-fruit industry in China.China is the largest apple producing country in the world and the apple production and planting area are still expanding.Meteorological conditions are the key factors affecting apple yield.In order to explore the impact of climate change on apple production regions,analyze the risk of disasters caused by water deficit and surplus in apple growing regions,and explore the research of apple drought insurance products,this study was carried out.The interannual and spatial distributions of the climatic indicators affecting apple planting were analyzed,while climate trend rate and ArcGIS spatial interpolation were applied,based on meteorological grid data of 5km×5km from 1981 to 2010.The unplantable areas where climatic conditions cannot meet the basic requirements for apple cultivation were excluded.Climatic suitability evaluation was carried out for plantable areas.The interannual variation characteristics in the suitable for growing apples areas are analyzed.Based on the crop water deficit and the days of continuous rain,drought index and continuous rain index were constructed for disaster risk analysis by 756 station data spatial resolution from 1981 to 2010.The plantable areas,drought risk and continuous rain risk were verified and evaluated by using meteorological station data from 2011 to 2018.Combining with apple yield data,the drought index insurance was constructed in Weifang city,Shandong province.The main conclusions are as follows:(1)Based on the suitable climate for apple planting from 1981 to 2010,apple can be grown in north China,northwest,southwest and parts of east,central and south China;in the plantable areas,the suitable regions were mainly located in most areas of the Loess Plateau and the Bohai rim area;the sub-suitable regions are mainly located in the North China Plain and a small part of the Loess Plateau,as well as the Tarim Basin and the Yunnan-Guizhou Plateau;the unsuitable regions are mainly distributed in the Northeast,most areas south of the Yangtze River,the Qinghai-Tibet Plateau,and parts of northern Xinjiang;Compared with the 1980s,in the 1990s and the 2000s,the Shandong Peninsula and the southern Loess Plateau had evolved from suitable planting regions into sub-optimal planting regions,however,the border areas between Liaoning and Mongolia,the Yunnan-Guichuan border areas,the northern Loess Plateau,and the border between Shaanxi and Gansu had evolved from the sub-suitable planting regions into the suitable planting regions.On the whole,the change was obvious that areas suitable for growing apples had moved northward and westward in China under the background of climate change.(2)From 1981 to 2010,the CWDI gradually increased in different stages of apple growth period,and the maturity period is the most important period for drought risk prevention because of the high level drought occurred widely and frequently.According to the situation of apple water deficit growth stage and drought frequency,CWDR drought index was built for drought risk zoning.The drought risk of apples in the plantable area increased from south to north,and the risk increased with the change of age,which mainly manifested as the expansion of drought risk range and the elevation of drought risk level.In the process of annual apple growth,the distribution of drought risk in each stage of the growth period was slightly different.The drought risk level in each stage of apple growth period in Bohai Rim area and Loess Plateau area showed a trend of southward expansion with time.(3)Continuous rain risk index(L_u)was built for risk zoning according to the comprehensive analysis of the occurrence times,duration days and occurrence intensity of continuous rain.In the plantable areas,the risk of continuous rain decreased from southwest to north from 1981 to 2010.The Yunnan-Guizhou Plateau and the Loess Plateau are the regions with high risk of continuous rain,while the regions with low risk of continuous rain are central Xinjiang,western Inner Mongolia,central Gansu and Bohai Rim region.(4)The distribution of heat resources and water resources changes under climate change from2011 to 2018,so areas suitable for growing apples had moved northward and westward.In general,the intensity of drought increased from southeast to northwest,and the frequency of drought increased in the Loess Plateau area of northwest China while the frequency of drought decreased slightly in the Bohai Rim.The risk of continuous rain decreased from south to north and the frequency and intensity of continuous rain increased in Gansu and Henan province.The range and intensity of disasters are consistent with the distribution of drought risk and continuous rain risk from 1981 to 2010.(5)Weifang city,Shandong province,was selected for typical year analysis of drought risk.In each stage of the growth period,drought risk presented a trend of increasing gradually.Logistic distribution was used to fit the apple yield reduction rate in Weifang city,and the different probabilities of yield reduction rate were obtained.The pure insurance rate of drought disaster to apple was calculated to be 0.555%,while the actual rate was 0.804%.According to the compensation conditions in the policy terms and in combination with the actual drought disaster,the compensation amount under different drought disaster levels can be obtained.Based on the high-resolution meteorological grid data,the study was focus on the relevant climatic factors and climatic suitable areas of apple planting in China,which had the high reference value for apple planting area adjustment.Analyzing the disaster risk of drought and continuous rain in the plantable areas,and designing apple drought index insurance with drought risk index and actual insurance policy had certain guiding significance for apple industry to avoid disaster,reduce loss and ensure production.In the future research on apple disaster risk,the adaptability of different regions and apple varieties to meteorological factors should be considered,and the actual conditions such as land use and irrigation should be taken into consideration,so as to realize the stable development of apple industry.