Risk assessment and zoning of drought for summer maize in the Huang-Huai-Hai Region

The Huang-Huai-Hai Region is one of China's major grain producing areas, especially summer maize. Thus drought risk assessment of summer maize in the Huang-Huai-Hai Region is critical in developing countermeasures to ensure grain security. This article assessed and zoned drought risk for summer maize cultivated in the Huang-Huai-Hai Region using the principles of natural disaster risk assessment along with meteorological data, terrain data, land use data and other relevant data in the Huang-Huai-Hai Region. The study also used spatial analysis techniques such as weighted comprehensive analysis (WCA), analytic hierarchy process (AHP) and Geographic Information System (GIS) as well as information diffusion theory. There has been extensive research involving the use of the principles of natural disaster risk assessment in recent years. This study calculated comprehensive drought risk index from three angles - disaster hazard, sensitivity and vulnerability. The selection of hazard index is critical and indicators such as precipitation and standard precipitation index (SPI) hardly precisely calculate the probability distribution of a specific drought index. This defect could be compensated for by using information diffusion theory. Firstly, percent precipitation anomaly was used as basic hazard index in calculating probability distribution based on information diffusion theory. The probability distribution of percent precipitation anomaly was divided by drought grade. Secondly, a weighted comprehensive analysis was conducted to determine hazard degree. The final results were calculated by selecting corresponding indicators for sensitivity and vulnerability. In this way, drought disaster risk for summer maize in the Huang-Huai-Hai Region was zoned based on a comprehensive hazard, sensitivity and vulnerability risk index. The results showed significant spatial differences in hazard sensitivity, vulnerability and comprehensive risk index for summer maize in the Huang-Huai-Hai Region. Drought hazard was relatively high and drought frequency exceeded 64.36%. The highest hazard areas were mainly distributed in the northern parts of Hebei Province and Anhui Province. The drought disaster sensitivity of summer maize in the Huang-Huai-Hai Region was higher, areas with high sensitivity grades accounted for 20.80% of the total area, which was mainly distributed in the coastal areas of Shandong Province. Overall, the region's drought disaster vulnerability of summer maize was low. The highest and higher vulnerability areas accounted for 22.4% of the total area, and distributed in every province. The comprehensive drought risk index for the whole study area was high with the highest and higher risk areas accounting for 68.43% of the total area. The whole of Huang-Huai-Hai region was in high risk hazard zone, except for southeastern Anhui Province.