基于改进TOPSIS模型的西部河谷型城市生态安全时空分异及障碍因子诊断

西部河谷型城市生态安全及障碍因子诊断对协调西部地区城市生态环境保护与社会经济产业持续发展具有重要意义。基于PSR模型集成改进TOPSIS和障碍度诊断模型,选取2005-2015年西部地区20个典型河谷型城市为评价单元,对生态安全系统时空演化规律及障碍因子进行实证分析。结果表明:1)西部河谷型城市生态安全水平整体呈上升趋势,但总体处于临界安全级(Ⅲ)水平;2)生态安全呈西高东低、北高南低的空间格局特征,生态安全空间差异性明显,但随着时间推移,各城市生态安全差异有缩小趋势,生态安全水平下降的城市数量在减少,生态安全水平上升的城市数量在增加;3)准则层中用地状态和经济响应是制约生态安全的主要障碍因子,指标层中环保投入占财政支出比重、人均公园绿地面积、人均水资源占有量、人均耕地面积、人均城市道路面积、科技投入占财政支出比重、城镇化水平7项因子成为主要的障碍因子。因城市规模不同,西部河谷型城市生态安全主要障碍因子变化特征不一。

Spatial-temporal discrimination and the related obstacle factor diagnosis for the valley cities urban eco-security in China west based on the improved TOPSIS method

The present paper takes the valley cities in China west as the case study sampling area based on the PSR model and the improved TOPSIS method. For the research purpose,we have chosen 22 factors to build up our evaluation index system to examine and measure the ecological security levels during the decade of 2005-2015 and summarize the temper-spatial features of the ecological security of the west valley city. And,then,the obstacle factors are diagnosed by using the disorder degree model. The results of our examination and evaluation indicate that:( 1) For the decade of 2005-2015,the ecological security of the valley city indicates a rising trend. The average status-in-situ of its eco-security has increased from 0. 504 1 in 2005 to 0. 542 6 in 2015. And,in general,its ecological security has been uprising. Nevertheless, its ecological security level remains at grade Ⅲ for the time being,which indicates that the ecological security situation remains quite ordinary with the ecological environment still facing tremendous pressure and challenge;( 2) The ecological security is higher in the west and north,whereas lower in the east and south. The ecological security index in the western part of the valley city remains at a lower level. As an integrated whole,the spatial gap of differentiation remains obvious,though its regional difference has been made gradually abbreviated in recent years. The number of cities with the declining ecological security level has been decreased,whereas the number of cities with rising ecological security level is increasing;( 3) The main challenging obstacle factors in the index layers influencing its ecological security are the poor ratio of the environmental protection investments in the state financial expenditure,with the area of per-capita park green space,the per capita water resource share,the per capita share of the cultivated lands,the per-capita science and technology development benefits share in the state financial expenditure,as well as the general level of urbanization. And,due to a great variety of ecological security,great variety can be found from city to city due to their different levels of the urbanization stages and scales.