Environmental Assessment Methodology Based On The Concept Of Fuzzy Weighted Distance

Environmental Assessment is a quantitative or qualitative evaluation process for the regional environmental quality or pollution extent in accordance with a certain of environmental quality standards and methods. Its purpose is to accurately present the pollution status and clarify the development trend of the environmental quality for the regional environmental planning and management.Since only the extent to which the pollutant concentration exceeds the environmental standard was taken into account in the classical Comprehensive Index Assessment Methods for the environmental quality assessment, in which the simplified mathematical formula was also used, sometimes there was certain falsity in the results of the Index Assessment Methods.As the pollution level, classification-level concepts are of the fuzzy concept and fuzzy phenomena, fuzzy mathematical method is more suitable for environmental quality assessment than the Index assessment method. But by means of analysis and examples of real applications, it showed that the commonly used Fuzzy Comprehensive Assessment Model, for example M (∧,∨)-in which "∨" means "maximizing operator" whileas "∧" means "minimizing operator", may lead to unclear or even mistaken assessment results since only the maximum and minimum value of the data were taken into account in the process of the assessment.In this thesis, by means of the concept of the fuzzy weighted distance by which the difference between the monitored samples and the environmental quality standards can be objectively expressed, the improved Environmental Quality Fuzzy Assessment Model that can make full use of the information contained in monitored data was proposed based on the concepts of the relationship degree and membership degree. An example application of assessment results showed that the fuzzy assessment model proposed was more reasonable than the Fuzzy Comprehensive Assessment Model in the process of the environmental quality assessment. Furthermore, according to the fact that the urban environment consists of multi-criteria and multi-stage environmental systems, based on the fuzzy assessment model, a new multi-level fuzzy assessment method for the overall urban environmental quality assessment was proposed with the case study.Similarly, according to the fuzziness and relativity of the environmetal evaluation process with multi-criteria, such as the risk assessment of the pollution accidents, based on the concept of the fuzzy weighted distance by which the difference between the assessed samples can be objectively expressed, the Fuzzy Evaluation Model for Environmental Pollution was proposed to make full use of the information contained in monitored data. On this basis, the multi-criteria and multi-stage fuzzy evaluation method was proposed for the environmental evaluation with hierarchical structrue. By means of the case study and comparative analysis, it showed that the fuzzy evaluation method proposed was more reasonable and advantageous than the conventional Linear Weighted Sum method.