Environmental Impact Assessment of a project consists of analyzing the impacts during construction and operation on environmental factors such as physico- chemical, biological and socio-economical. Determining the impacts derived from these analyses is done by experts utilizing statistical analysis tools and local surveys. Meanwhile because of the lack of information, the application of semantic and quantitative variables increase in order to describe them, which results in high degree of uncertainty and unreliability. In this regard using an appropriate approach like fuzzy logic facilitates the achievement of tangible results, according to its ability to illustrate the level of uncertainties by full integration of qualitative and quantitative information and efficient management.
In this study a method of environmental impact assessment, based on fuzzy matrix is proposed to assess the Golestan Forest Highway project. Main activities at this project (A) and important environmental factors (F) that are influenced by these activities were determined to construct matrixes and each effect (A-F) was estimated regarding three properties which are intensity, extent and persistency in the form of triangular fuzzy numbers. Finally all of the positive (EI⁺ ) and negative (EI⁻ ) effects that induced by this project were computed and the total amount of environmental impact (EI) is obtained.