Because of the imprecision of the ecological impacts and the frequent lack: of quantitative information, fuzzy theory provides a useful approach to the environmental impact evaluation. In this paper, the environmental parameters are defined through fuzzy numbers. By considering the duality of the global component as derived from primitive environmental components, for these primitive components the quality is generally derived from their fuzzy physical parameters. Suitable operators are proposed in order to estimate the global environmental component quality as a function of environmental primitive components quality that cam decrease or increase the environmental quality. Also in fuzzy form the magnitude of the plant impact factor that strikes the environmental components is esteemed. This magnitude is a function of environmental parameters that can be fuzzy, as fuzzy can be the relation between these parameters and the magnitude of the impact factor. Therefore, through the matrix method, the total environmental impact (T.E.I.) in fuzzy terms is calculated, as in fuzzy form, the percentage of impact on every environmental component is calculated. A criterion is proposed in order to compare fuzzy T.E.I. for various sceneries. This criterion is based on a ranking method that considers the grade of prudence of the decision-maker and the acceptable risk. Finally, a case study is reported as an explanation of the method. (C) 2001 Elsevier Science B.V. All rights reserved.
