Risk Assessment Of Heat Injury For Single-season Rice In Jiangsu And Anhui Province

As the main output provinces of single-season rice in the middle-lower Yangtze rive areas, the rice of Jiangsu and Anhui province is always subjected to high temperature damage in its critical period. In this paper, based on daily meteorological data during 1961-2015 and phonological observation data from 1993 to 2013 in Jiangsu and Anhui province, the temporal and spatial distribution of heat injury and the characteristics of periodic variation were analyzed by station proportion and frequency during booting and heading stages. On the basis of the times of high temperature, hazard model was established. The ratio of planting area and agricultural acreage was used as the index of exposure model. Based on the rice growth model-ORYZA2000, the actual yield and normal yield were simulated by running different weather files. The vulnerability model was built by the index of yield reduction rate variation coefficient. Per person of farmers net income,agricultural machinery total power and the total amount of agricultural fertilizer were selected as prevention and mitigation capacity assessment indexes. Constructing the risk assessment model for heat injury in accordance with the theory of "Four Elements" and based on the ArcGIS,the risk regions of Jiangsu and Anhui province were divide into low value area, sub-low value area, sub-high value area and high value area.The main conclusions were follows:(1) During the past 55 years(1961-2015), the range of the area suffered heat damage was slight>severe>moderate over Jiangsu and Anhui province. There were periodic fluctuations and the time scale of quasi 13a was the first major cycle of single-season rice during the booting and heading stages in Jiangsu and Anhui province. Besides, The frequency of heat injury for different grades and the average heat injury days were decreasing from southwest to northeast in the study regions. In addition, the low value area was distributed in the coastal area of Jiangsu. Entering the 21st century, high temperature damage occurred more frequently during the period of booting and heading stages;(2) There was a certain planting regions of single-season rice in study areas.Hazard and vulnerability of heat injury were gradually increased from the coastal to inland, while the prevention and mitigation capacity showed the opposite trend;(3) The risk of heat injury was similar to the distribution trend of hazard and vulnerability. It was also increased from coastal to the inland. The different grades of risk showed a certain continuity and lamellosity in the spatial distribution. The high and sub-high risk area were mainly located in the west, southwest and south of Anhui province and sub-low risk region was in the central, east of Anhui and the west of Jiangsu province. The low risk area was mainly distributed in Jiangsu province.