Assessment of Autumn Drought Risk of Sugarcane in Guangxi

Guangxi is one of the annual precipitation-rich regions of the country. However, seasonal drought occurs in high frequency because of spatiotemporal nonuniform distribution of rainfall. Seasonal drought has rather large influences on the agricultural production, especially on the sucrose industry, which is one of the most important economic pillar industries in Guangxi. Autumn is the critical elongation and sugar accumulation stage for sugarcane. Severe autumn drought will cause a decline in production, or which at sugar accumulation stage, will decrease sugar content, increase pectin weight, reduce sugar yield and recovery rate, and cause a decline in commodity quality. Therefore, it will affect the sugar market and the whole industry chain, as well as sugarcane farmers and the local agricultural economy. In order to strengthen the risk assessment and emergency management capability of the autumn drought disasters of sugarcane, according to the concept of risk triangle, the autumn drought risk assessment indicator system is established. Indicators of system are determined according to drought risk, possibility of disaster, vulnerability of disaster bearing body, by use of meteorological data, vegetation, basic geographic information and socio-economic data from the database. The database is constructed for risk assessment of drought disasters of sugarcane, including disaster-causing factors (such as rainfall), disaster-forming environment (such as topography, hydrographic net, vegetative cover, etc.), disaster bearing body (such as sugarcane planting area, economy, etc.), and disaster prevention and mitigation capability (such as reservoir and other water conservancy facilities). Then factor weights are obtained by analytic hierarchy process (AHP), and the comprehensive assessment model is established and calculated to get the disaster risk index, which are regionalized by geographic information system (GIS). The distribution indicates that the highest and higher risk areas include the part of Laibin and Chongzuo, which are the largest main sugarcane-producing regions, at the top of the planting area list, the medium risk area consists the most part of Chongzuo, the east and west of Laibin, the south-central of Liuzhou, the west of Nanning, and the lowest risk areas include the southeast of Guangxi.Validating results show that the distribution of autumn drought disaster risk of sugarcane is basically consistent with the spatial distribution of drought disaster losses. The analysis also shows that regional differences of drought risk of sugarcane is reflected, because of different effects of hazard, formative, damage and disaster relief, by choosing the right and feasibility evaluation metrics appropriately. Above all, the autumn drought risk assessment method is feasible by introducing risk triangle theory and taking advantage of AHP and GIS, and the evaluation is more reasonable with higher verification accuracy.