基于GIS的城市工程地质环境质量变权评价

On the synthetic evaluation of the GIS-based variable weight of the urban geological engineering environment quality

城市工程地质环境质量传统评价方法中,指标权重确定后,无论各指标值如何变化,指标权重值总是固定不变,无法反映各项指标内部差异性对城市工程地质环境质量的影响,进而影响评价结果的客观公正性。为此,将变权原理引入城市工程地质环境质量评价。根据城市工程地质环境特点及评价精度要求,构建城市工程地质环境质量评价指标体系,采用分段强惩罚-激励型变权模型,并结合GIS空间分析功能对其进行评价。以郑州市为例,采用常权和变权两种方法对其工程地质环境质量进行评价。结果表明,变权评价结果与常权评价结果趋势性较为一致,且变权评价结果比常权评价结果更易区分评价等级,在一定程度上避免了常权法在权重分配中的缺陷,充分体现了各项评价指标内部差异性对城市工程地质环境质量整体性的影响,提高了城市工程地质环境质量评价等级的可信度。

In this paper,we would like to introduce the variable weight theory into the system of urban engineering geological environment quality evaluation.The method we introduce here involves three stages.In the first stage,the goal is to establish the index system for quality evaluation of urban geological engineering environment based on study of the characteristics of the urban engineering geological environment.The goal of the second stage is to calculate the constant weights,known as ＂the basic weights＂,by the analytical hierarchy process.And,the goal of the third stage is to build up a segmented strong penalty-incentive variable weight synthetic model according to the data types of the indexes and evaluation precision requirements.If the above said three stages were done,it would be possible to double the spatial analysis capacity of the quality evaluation of the urban geological engineering environment.By applying the device,we have done the related evaluations of the constant weight and the variable weight respectively for the main urban areas of Zhengzhou City.The analysis indicates that the evaluation result gained by using the device we have developed proves to be in conformity to the results gained by using traditional methods and other similar methods.Moreover,the discreteness of the variable weight evaluation result proves to be better than that of constant weight results,which are used to distinguish the quality grades of such geological environments.Therefore,it can be said that the variable weight method here introduced can help to get rid of the defects of such evaluation.What is more,the variable weight method put its focus on punishing worthless values of the indexes and encouraging the positive ones.In addition,the method can also fully reflect the effects of internal different grades of every index on the comprehensive evaluation results of the urban engineering geological environment quality.Thus,it can be concluded that in comparison with the traditional methods,the renovated method significantly can greatly improve the reliability of the quality evaluation grades on the urban engineering geological environment.