基于正交投影法改进TOPSIS模型的宁夏农业干旱风险评价

Assessment of Agricultural Drought Risk Based on Improved TOPSIS Method in Ningxia

【目的】科学有效对宁夏农业进行干旱风险评价。【方法】基于自然灾害风险理论,利用宁夏5市气象和社会经济等方面的数据,从农业干旱危险性、暴露性、脆弱性和抗旱能力4方面选取32个评价指标构建宁夏农业干旱风险评估指标体系;通过主成分分析将指标简化为10个相互独立的主成分,采用熵权法确定主成分权重,并基于正交投影法改进TOPSIS模型,得出各主成分"垂面"距离Pi,依据Pi值越小风险越大的原则,对宁夏5个市的农业干旱风险进行评价。【结果】银川、石嘴山、吴忠、固原和中卫的主成分到正理想解的"垂面"距离Pi分别为0.045、0.035、0.037、0.026、0.033,农业干旱风险由高到低依次为固原>中卫>石嘴山>吴忠>银川,与雷达图法分析的近1949—2013年的实际旱情程度及空间分布较为一致,表明改进TOPSIS模型适用于宁夏农业干旱风险评价。【结论】为有效降低未来潜在的农业干旱风险,宁夏全区需树立"以水定结构、以水定面积、以水定产量"的农业灌溉用水管理理念,适当调整与优化作物种植结构,大力发展高效节水灌溉,加快建设库坝窖池井工程联调体系,按照"北部节水、中部调水、南部开源"的治水思路对水资源进行合理调配,同时加快旱情监测网络建设及抗旱服务体系建设。

【Objective】Evaluate the drought risk of Ningxia scientifically and effectively.【Method】Based on the theory of natural disaster risk,using meteorological and social economic data of Yinchuan,Shizuishan,Wuzhong,Guyuan and Zhongwei,index system of agricultural drought risk assesment in Ningxia was established by selecting 32 evaluation indexes from 4 aspects including hazard of formation factors（H）,exposure of affected bodies（E）,vulnerability of formation environments（V）and drought-resistant ability（RE）.【Result】The results showed that through principal component analysis（PCA）and entropy weight method,improved TOPSIS method and vertical projection method,the vertical projection distance（Pi）of principal components of 5 cities（Yinchuan,Shizuishan,Wuzhong,Guyuan City and Zhongwei）to the ideal solution were 0.045,0.035,0.037,0.026,0.033,respectively.There was a difference of the agricultural drought risk between the north and the south in Ningxia,ranking from high to low was GuyuanZhongweiShizuishanWuzhongYinchuan.The data and distribution of drought risk in Ningxia calculated by the method of radar chart were consistent with the actual drought disaster data and spatial distribution from 1949 to 2013,which further validated the reliability and practicability of the method.【Conclusion】In order to effectively reduce the agricultural drought risk potential in the future,Ningxia should establish a＂Structure with water,Determination of area by water,Determine production by water＂of the concept of agricultural irrigation water management,in accordance with the idea of＂Northern watersaving,Central water diversion,Southern exploring resources＂,and accelerate the construction of drought monitoring network and drought service system.