基于不确定性的城市扩展用地生态适宜性评价

针对土地适宜性评价中采用定性和单因素方法而产生的主观、片面和精度低等缺点，分析了土地适宜性评价中的不确定性因素，并提出基于不确定性和灰色系统关联度的土地生态适宜性评价模型。结合长沙市生态规划，在野外生态调查的基础上，依据稳定性、独立性、主导性和综合性原则选取坡度、地基承载力、土壤生产力、植被、土壤渗透性、地表水、居民点用地程度、景观价值等土地生态适宜性评价因子。在地理信息系统（GIS）和遥感（Rs）的支持下，定量地获取各评价因子信息；采用AHP法确定各评价因子的权重；并运用改进的土地生态适宜性评价模型对长沙市城市扩展用地进行定性定量的评价，最终得到长沙市最适宜用地、适宜用地、基本适宜用地、不适宜用地、不可用地分别占总用地的14．77％、16．64％、24．07％、30．91％、13．61％，说明长沙市适宜开发的土地较多（最适宜、适宜和基本适宜用地占55．48％）。根据评价结果提出的相应对策，对城市用地的可持续性发展具有指导意义。

The ecological suitability evaluation on urban expansion land based on uncertainties

Land suitability evaluation is used to define a land's suitability for certain use by synthetically evaluating its hydrology,geography,terrain,geology,biology,human culture etc.At present it has been widely used in the filed of agriculture,forest,urban expansion land and so on.However,the qualitative method and single factor method adopted in land suitability evaluation are of disadvantages of subjectivity,unilateralism and low precision;meanwhile,they are of many uncertainties in quantifying factors,and modern information technologies,such as remote sensing,are rarely applied to evaluation.Compared with the traditional numerical evaluation,land suitability evaluation based on Remote Sensing(RS) and Geography Information System(GIS) is more simple,intuitionistic,convenient and fast in evaluating the land's suitability as it is the integration of ground information obtainment,numerical calculation and space data analysis.In the process of evaluating land's suitability,uncertainties occurs in classified quantification;for example,the difference in the same classification but at different levels can not be distinguished,and the difference among different classifications in the boundary is overextended.Based on the analysis of uncertainties,grey correlation analysis is brought forward to modify Land Suitability Evaluation Model(LSEM).In the Ecological Planning for Changsha Eco-city,some land ecological suitability evaluation factors are selected after ecological investigation under the principle of stability,independence,dominance and integration,which are slope,carrying capacity of foundation,vegetation,soil productivity,soil permeability,surface water,extent of resident land use and landscape value.The information of some evaluation factors such as vegetation,surface water,extent of resident land use and landscape is quantitatively obtained by interpreting Landsat-5 TM remote sensing image data;and the information of soil productivity,soil permeability and carrying capacity of foundation is obtained by field sampling and investigating;other information such as topographic map is collected.All usable information is input to computer to build the GIS database.The weights of factors used for evaluation are decided by the method of AHP(Analytical Hierarchy Process).Changsha urban expansion land ecological suitability is qualitatively and quantitatively evaluated by the modified land suitability evaluation model.As a result,the percentage of the highly suitable land,suitable land,moderately suitable land,not suitable land and permanently not suitable land respectively is 14.77%,16.64%,24.07%,30.91% and 13.61%;most of the land is suitable for construction(the total percentage of highly suitable, suitable and moderately suitable land is 55.48%).The effective strategies based on the evaluation results can be used as the reference for urban land planning and land evaluation.