| This paper analyzes the spatial-temporal characteristics of agricultural meteorological disasters for maize in terms of the meteorological data, crop data and disaster record information in the three provinces of northeast China during 1981-2010. A new trend yield fitting method was presented. A comprehensive risk assessment model for varied disasters and an agrometeorological hazard risk comprehensive assessment model were developed for the three provinces of northeast China, which considered the vulnerability of hazard object body, the exposure of disaster pregnant environment and regional disaster prevention and reduction ability. The main results could be summarized as four aspects as follows:(1) The trend yield fitting method for maize in the three provinces in Northeast China is determined. The comparison and verification of different trend yield fitting methods indicates that the Logistic curve fitting method is the best one for fitting the reduction rate of meteorological yield with the average accuracy of 83%, followed by the cubic polynomial curves (81%) and the linear sliding average method (80%). The lowest average accuracy of fitting reduction rate of meteorological yield is given by the moving average method and the weighted moving average method. Thus, the meteorological yield got by the Logistic curve fitting method is able to reflect the effect of the meteorological factors on the maize yield best.(2) The classification method of disaster intensity grade for the three province in Northeast China is proposed. Based on the agricultural meteorological disasters of maize occurred in Northeast China, the main disaster indices of maize in the three provinces of Northeast China are determined, and a set of the classification standards for maize agricultural meteorological disasters is proposed. The intensity grade of agricultural meteorological disaster is also adjusted, in terms of Grand Ceremony of Meteorological Disasters in China, Yearbook of Meteorological Disasters in China and the responsible meteorological reduction rate of maize yield.(3) The spatial and temporal characteristics of frequency and intensity of the main agrometeorological disasters in the three provinces of northeast China are illuminated. The frequency of main agrometeorological disasters is ranged as chilling disaster (41%)> drought disaster (39%)> water-logging disaster (38.5%) in the three provinces of Northeast China. The spacial scale of chilling disaster decreases with time, ranged as moderate> mild> severe. Chilling disaster frequency is ranged as Heilongjiang> Jilin>Liaoning provinces, and the high value area of severe chilling disaster frequency is located in the northwest of Heilongjiang province, while the low value area is located in the southern and central parts of Liaoning province. The spacial scale of drought disaster increases with time, ranged as severe> mild> moderate. The lower frequency of drought disaster is in the middle zone, while the higher is in the northern and southern zone.The spatial scale of water-logging disaster decreases with time, ranged as severe> mild> moderate.The frequency of flood and water-logging disaster shows a decreasing trend from northwest to southeast overall. By the EOF decomposition of disasters, we can find that the climate is different in the three provinces of Northeast China, however, the agricultural meteorological disasters show increasing or decreasing tendency consistently.(4) The comprehensively the risk of main agrometeorological disasters in the three provinces of northeast China is assessed. Based on the method of hazard risk system, we establish the comprehensive risk assessment model of agrometeorological disasters in the three provinces of Northeast China. For the risk distribution of single disaster, the highest risk area of chilling disaster mainly is located in the northwest and southeast of the three provinces of Northeast China, and the minimum risk area is located in the northwest of Liaoning province. The highest risk area of drought disaster mainly is located in the northeast of Liaoning province and the southwest of Jilin province, and the minimum risk area is located in the mid-west of Heilongjiang province. The highest risk area of flood and waterlogging disaster mainly is located in the southwest of Liaoning provinces, and the risk intensity gradually reduces to the northeast area. For the risk distribution from multiple disasters, the highest risk area mainly is located in Da Hinggan Mountains and Xiao Hinggan Mountains of the three provinces of Northeast China. The risk of Heilongjiang is the highest. The risk gradually reduces from the north to the south. The vulnerability is fragmented in the three provinces of Northeast China, and the lowest area is mainly located in the western parts of Jilin province. The exposure of the center west in Jilin province is the highest, and decreases to east, south, north direction. The capacity of disaster prevention and mitigation of outlying area in the three provinces of Northeast China is the lowest. The highest value area of comprehensive risk index of main agro-meteorological disasters mainly is located in the west of Heilongjiang and Jilin provinces, shows a decreasing trend from northwest to southeast overall. |
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