广西甘蔗秋旱灾害风险评估技术初步研究

Assessment of Autumn Drought Risk of Sugarcane in Guangxi

为增强对广西甘蔗秋旱灾害的风险评估和应急管理能力,利用气象、植被、基础地理信息和社会经济数据,根据风险三角形理念,从广西甘蔗秋旱灾害的危险度、受灾可能性和承灾体脆弱度3个方面,选择因子构建甘蔗秋旱灾害风险评估的指标体系,采用层次分析法构造判断矩阵以确定各指标和因子的权重,构建评估模型,并计算广西甘蔗秋旱灾害风险指数,再基于GIS绘制广西甘蔗秋旱灾害风险区划,结果显示:高风险区和较高风险区主要分布在来宾和崇左等市的局部地区,低风险区主要分布在桂东南地区。利用灾情数据进行验证表明:广西甘蔗秋旱灾害风险分布与甘蔗灾情损失空间分布情况基本一致。

Guangxi is one of the annual precipitation-rich regions of the country. However, seasonal drought oc- curs 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 accu- mulation 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 in- dustry 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, ac- cording 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 dis- aster bearing body, by use of meteorological data, vegetation, basic geographic information and socio-eco- nomic data from the database. The database is constructed for risk assessment of drought disasters of sug- arcane, including disaster-causing factors（such as rainfall）, disaster-forming environment（such as topogra- phy, hydrographic net, vegetative cover, etc. ）, disaster bearing body（such as sugarcane planting area, e- conomy, etc. ）, and disaster prevention and mitigation capability（such as reservoir and other water conser- vancy facilities）. Then factor weights are obtained by analytic hierarchy process（AHP）, and the compre- hensive 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, dam- age 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 ad- vantage of AHP and GIS, and the evaluation is more reasonable with higher verification accuracy.