Risk assessment of hot damages for single-cropping rice based on accumulation index of heat stress in Sichuan

Under global climate change, agricultural meteorological disasters have been increasing. Heat stress has been one of the most important agro-meteorological disasters in Sichuan Province, and the affected area and frequency and intensity of heat stress have significantly changed. Therefore, research on the effect of heat stress on rice is critical for sustainable agricultural development and safe production in Sichuan Province. Heat damage risk of single-cropping rice in Sichuan was studied using meteorological, agricultural meteorological, statistical, and geographic data during 1986-2015. Four factors, which were hazard, sensitivity, exposure, and disaster prevention and mitigation capacity, were created with the cumulative high temperature-induced damage index, topography, yield variation, and rural economy as the basic indexes to evaluate heat damage risk during the sensitive stages of heading, flowering, and filling. A "Four Factors" multi-risk assessment index system of heat injury for single-cropping rice in Sichuan Province was established by using the Grey Correlation method, and used in the risk regionalization of single-cropping rice of the study area. The results of the multi-risk assessment model were valuable for making decisions to relieve disaster risk. The assessment results showed that the parallel ridge-valley region of the eastern basin, the shallow hilly area of the central basin, the west part of mountain area around the basin, and the southern hilly area of the southern basin were divided into high-risk areas with gentle topography and frequent heat damage. Plain and hill areas of the western basin and mountain area of southwest Sichuan were roughly divided into medium risk areas with good irrigation conditions, higher socioeconomic developmental levels, and good coping abilities. The wide valley area of Southwest Sichuan and mountain area around the basin were roughly divided into low risk areas where the regional topography is complex, and less rice is planted. In summary, there were clear differences in heat damage risks on single-cropping rice in different regions in Sichuan. Reasonable varieties and cultivation modes should be chosen to raise prevention and reduction ability based on different regional risk characteristics.