基于AHP和GIS的广西秋旱灾害风险等级评估

    Assessment of risk ranking for autumn drought in Guangxi province based on AHP and GIS

    • 摘要: 为增强对广西秋季干旱灾害的风险评估和应急管理能力,该文利用气象、基础地理信息和社会经济数据,从广西省秋旱灾害致灾因子的危险度、孕灾环境的脆弱度、干旱承灾体的易损度和抗灾能力等4个方面选取因子,构建秋旱灾害风险评估的指标体系,通过层次分析法确定因子权重,以此构建评估模型并计算广西秋旱灾害风险指数,再基于GIS绘制广西秋旱灾害风险等级分布图。结果表明,高风险区主要分布在桂中盆地和桂西部分山区;较低风险区主要分布在桂西北和桂北的山区,桂南沿海和桂东南部分地区。利用广西干旱灾情数据验证表明,广西秋旱灾害风险等级分布结果与干旱灾情损失空间分布情况基本一致。该研究为灾害风险管理和灾前防御提供决策依据。

       

      Abstract: Abstract: Guangxi is one of the annual precipitation-rich regions of the country. But seasonal drought occurs very frequently because of spatio-temporal nonuniform distribution of rainfall. Seasonal drought has a rather large influence on the water resources, industrial production, and human life, especially on the agricultural production of Guangxi. The research there has been mostly aimed at some characteristics of a certain domain (such as agriculture) in the application .And some evaluation processes too depended on subjective experience or a simple formula, and did not comprehensively consider the influence to society's economy and environment of drought disaster, the vulnerability of the disaster bearing body, and the ability to prevent and reduce disaster. In order to strengthen the risk assessment and emergency management capability of the autumn drought disasters of Guangxi, an autumn drought risk assessment indicator system was established, and its indicators were determined according to drought risk, sensitivity of disaster environment, vulnerability of disaster bearing body, ability of disaster prevention and reduction, included rainfall anomaly, little rain days anomaly, topography, hydrographic net, Karst landform, population density, gross domestic product(GDP), arable area, pecuniary loss and real GDP per capita, by use of meteorological data, such as daily rainfall of 88 meteorologic stations, from 1961 to 2010, basic geographic information, consisting of 1:50 000 scale county boundary and hydrographic net, digital elevation model(DEM) (about 100m resolution), and Karst landform(about 1000m resolution), and socio-economic data, containing population density, GDP, real GDP per capita, arable area and pecuniary loss, taking the county as a unit. Then factor weights were obtained by an analytic hierarchy process (AHP), which relied on a judgement matrix and its eigenvalues and eigenvectors, and a consistency test of the matrix, and comprehensive assessment models for agriculture and social economy were established and calculated to get the autumn drought disaster risk index, which ranked distribution by a geographical information system (GIS).The distribution indicated that the higher risk area contains the west of Chongzuo, central and south of Baise, east of Hechi, south of Liuzhou, east and south of Guilin, central and northwest of Laibin, urban of Guigang, and some counties of Nanning. The lower risk area contains the northern mountainous area of Baise, Hechi, Liuzhou and Guilin, most of Fangcheng and Beihai, central and south of Yulin, and most of Pingnan, Guiping, Zhaoping, and Mengshan. Finally the condition of drought disaster was used to validate the distribution. The correlation coefficients were 0.58441 and 0.60393, respectively, of agriculture and social economy, through significance test by 0.05, using the correlate analysis method, by the multivariate analysis tool of ARCGIS. The results showed that the distribution of autumn drought disaster risk is basically consistent with the spatial distribution of drought disaster losses, which in the high risk area are mainly distributed in the middle basin and mountain area in the west, and are low in the mountain areas in the northwest and north, coastal area in south, and parts of the southeast of Guangxi. The results reflected preferably regional differences of drought risk, which were due to the distinction of formation, environment, bearing body and prevention of autumn drought disaster of Guangxi. The drought assessment model and method used combine the advantage of AHP and GIS, and can make drought evaluation procedure and evaluation results more scientific, increasing practicability and maneuverability.

       

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