基于变权的城镇用地扩展生态适宜性空间模糊评价——以江苏省太仓市为例

城镇用地生态适宜性评价有助于引导城镇用地合理扩展。针对传统评价方法的不足及生态适宜性的模糊性,提出基于局部惩罚型变权的空间模糊综合评价方法,并选择7项生态适宜性影响因素,在GIS软件的支持下对江苏省太仓市城镇用地的生态适宜性进行综合评判。结果显示,变权模型可灵活而合理地处理各评价单元各因素的权重值;研究区内适宜、基本适宜、较不适宜和不适宜于城镇扩展的土地分别占土地面积的25.89%、8.35%、37.43%和28.33%,其生态敏感性评价结果及其空间分布与实际相符,通过生态敏感性综合分值的比较可为城镇用地扩展区位选择提供依据。研究表明,基于变权的空间模糊综合评价凸显了"瓶颈"因素的否决作用,更能精确、合理地反映城镇用地扩展的生态适宜性状况。

Spatial Fuzzy Assessment of Ecological Suitability for Urban Land Expansion Based on Variable Weights:A Case Study of Taicang

Assessment of ecological suitability for urban land is playing an increasingly important role in urban planning because much more pressures on regional ecosystem are put by urban expansion,which has met the needs of regional economic development.Though great achievements have been made in related researches,constant weight assessment,as normally used method,should be substituted because it possibly gets unscientific results due to the neutralization of excellent indicators and bad ones.However,the theory of variable weights proposed by Wang Peizhuang could help to overcome those problems by considering the relationship of all indicators and enhance the impacts of prominent indicators.Therefore,based on the local punishment model of variable weights,the paper presents a method of spatial fuzzy comprehensive assement in order to settle the problems of traditional methods and to reflect the characteristics of fuzziness and spatial accuracy.The evaluation index system is established by choosing seven indexes which have influence on ecological suitability for urban expansion,and a case study in Taicang city was taken under the support of GIS software,so as to guide the urban land expand rationally. It is found that the model of variable weights could calculate the weights of various indexes of every grid flexibly and reasonably,thus make initial weights of different indexes change diversely according to relationship of all indexes of different grid units.Take the index of "distance to coastline of the Yangtze River and reservoir" as an example,the index weights in different locations change from 0.0388 to 0.5774,and the weights in the locations of the Yangtze River and reservoirs reach to 0.5774,which is 198.86% higher than initial weight(0.1932),so the index could increase the comprehensive value of ecological sensitivity for urban land expansion of those grids.According to the result of ecological suitability assessment,the study area was divided into four types: suitable land,moderately suitable land,little unsuitable land and unsuitable land.The area of each type respectively is 20871.09,6727.41,30169.71 and 22836.51 hm2,which is 25.89%,8.35%,37.43% and 28.33% of the study area accordingly.Moreover,the result of ecological sensitivity value also shows that the values of the grid units range from 0 to 8.9570,and their spatial distribution accords with the fact. The study indicates that the method of spatial fuzzy comprehensive assessment based on variable weights theory could not only make scientific evaluation on the ecological suitability for urban land expansion from microcosmic and spatial perspectives,but also highlight the importance of restrictive factors and make the vetoes of bottleneck factors effective,thus it could reflect the land ecological suitability status for urban expansion more accurately and reasonably.So it is of great help to provide a scientific basis for decision-making in urban planning and land use planning.