| China is one of the countries with the heaviest natural disasters in the world,there are a variety of types of disasters are widely distributed in China,resulting in a great social and economic losses.The losses caused by meteorologic disasters account for more than 70% of the losses in the natural disasters.Especially under the background of global warming,frequency of extreme weather events more than before,which aggravates the risk level of agro-meteorological disasters.Waterlogging disaster is the main disaster caused by extreme precipitation events,itis one of the natural disasters rank after the drought,whichseriously affecting the region's food security and regional sustainable development.As an important means to prevent the occurrence of agricultural meteorological disaster risk,it is an urgent problem for the relevant government departments and the agricultural production departments.Therefore,the research of the meteorological disaster has been paid more and more attention by domestic and foreign scholars.How to accurately and quantitatively assess the impact of waterlogging on the risk of agricultural production is of great significance to the current national agricultural structure adjustment,especially to the sustainable development of agriculture,agricultural flood control and waterlogging countermeasures.The dynamic assessment of agricultural meteorological disaster risk is the main development direction of agricultural meteorological disaster risk research,we can carry out disaster real-time and targeted prevention and mitigation according to the results of risk assessment.At present,most of the agricultural meteorological disaster risk assessment is static and post disaster assessment.A new generation dynamic assessment of waterlogging disaster risk for maize based on the mechanism of maize waterlogging disaster risk formation,regional meteorological and climate model,crop growth model and disaster risk assessment model was established from the soil-crop-atmosphere system and different maize growth stages.It is possible to estimate the occurrence and intensity of waterlogging at different growth stages,and to estimate the possible yield loss due to the different intensity of waterlogging disaster.In addition,the field scale data expressed in the regional scale for different scenarios of waterlogging risk assessment research using multi-source data mining and fusion technology.This study will make up for the lack of research on dynamic disaster risk assessment of Maize waterlogging,to solve the key issues related to the study,the results can be extended to other types of disasters in China,it is of great significance to improve the research level of agricultural meteorological disaster risk and emergency management ability,and achieve the goal of scientific disaster prevention and active disaster prevention.The main contents of the paper are as follows:(1)Identification of waterlogging risk factors in midwest of jilin provinceThe threshold of extreme precipitation events is defined by Multifractal detrended fluctuation analysis(MF-DFA)method.Extreme precipitation(EP),extreme precipitation ratio(EPR)and intensity of extreme precipitation(EPI)are selected as the extreme precipitation indicators,and then the Kolmogorov-Smirnov(K-S)test is employed to determine the optimal probability distribution function of extreme precipitation indicators.On this basis,copulas connect nonparametric estimation method and the Akaike Information Criterion(AIC)method is adopted to determine the bivariate copula function.Finally,we analyze the characteristics of single variable extremum and bivariate joint probability distribution of the extreme precipitation events.The results show that the threshold of extreme precipitation events in semi-arid areas is far less than that in sub-humid areas.The extreme precipitation frequency shows a significant decline while the extreme precipitation intensity shows a trend of growth;there are significant differences in spatiotemporal of extreme precipitation events.The spatial variation trend of the joint return period gets shorter from the west to the east.The spatial distribution of co-occurrence return period takes on contrary changes and it is longer than the joint return period.(2)Hazard assessment of waterlogging disaster for maize in the Midwest of Jilin Province,Chinafrom the perspective of Soil-crop-atmosphere system,the comprehensive risk index of waterlogging disaster was constructed by standardized soil moisture index,crop water surplus and deficit index and weekly SPI index,to analyze the dynamic risk of waterlogging for different maize growth stages in the Midwest of Jilin Province,and the dynamic risk of maize waterlogging at different growth stages was assessed.Based on the CA2 D hydrological model product data,the risk of waterlogging of the study area in different scenarios was evaluated.The results showed that there were many high risk areas of maize waterlogging during sowing-jointing stage and maturing stage,and mainly concentrated in the eastern and southern areas of the study area.The waterlogging hazard with the return period of 500 years was greater than 100 years,waterlogging disaster with the higher intensity,a wider range mainly concentrated in the northernerof the study area.(3)Vulnerability assessment of waterlogging disaster for maize in the Midwest of Jilin Province,ChinaThe effects of different disaster intensities on maize growth were analyzed by experiments of maize waterlogging stress in different growth stages.the CERES-Maize model was calibrated and identified to construct the vulnerability curve of maize waterlogging,and the vulnerability of maize waterlogging at different growth stages in Jilin central and western China was evaluated and zoned.The The results showed that with the increase of water depth and duration,the plant height,photosynthesis,chlorophyll and dry matter distribution of maize showed a decreasing trend.Maize waterlogging disaster is more vulnerable in Jointing-heading stages and heading-milky stages,whichmainly concentrated in the south and southwest of the study area.(4)Dynamic assessment risk of waterlogging disaster for maize in the Midwest of Jilin Province,ChinaCombining the waterlogging hazard index of meteorological-soil-crop system and waterlogging vulnerability index derived from the CERES-Maize crop model,the dynamic risk of waterlogging disaster in different growth stages of maize in typical cases(1994,2005 and 2010)of study area were assessed from the aspect of risk management mechanism.Waterlogging hazard index based on CA2 D hydrological model and the data of maize yield loss rate obtained from waterlogging stress test was integrated to assess the risk of waterlogging disaster for maize in different scenarios.The results showed that the area with high risk can be found in southern of the study area,and the area was increasing with the advance of maize growth period in 1994.The area with high risk of waterlogging disaster was relatively high in the growth stages of sowing-jointing and milking-maturity in 2005.in 2010,the high risk areas of waterlogging disaster were reduced.In the first two growth stages,they were mainly distributed in the northern part of the study area and moved to the southern in the latter two growth stages.Under the condition of return period of 500 years,the high risk area of waterlogging disaster was more than that of 100 years.The spatial distribution pattern was basically the same as the hazard of waterlogging disaster.(5)Study on application of dynamic risk assessment of waterlogging disaster for maize in risk managementAccording to the whole process of waterlogging disaster and the theory of waterlogging risk formation,this study proposed the ways and countermeasures of risk management for maize based on the whole process and the risk formation mechanism of waterlogging disaster.These multi-means,two-pronged and targeted approaches can minimize the impact of climate change on agricultural production and ensure the national food security. |
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