Estudos de impacte ambiental em infraestruturas rodoviárias com recurso a tecnologia SIG e avaliação multicritério

The Environmental Impact Study (EIS) is a key formal document in the Portuguese Environmental Assessment context procedure, which is required for an engineering project. This is the outcome of several methodological evaluation assessments and activities undertaken towards the identification of environmental impacts. It should present the mitigation measures and the monitoring plan. If there are several alternatives, the “most -environmental -friendly” should be indicated. This work proposes a methodology to support the Assessment procedure above in a GIS integrating environment. This combination of GIS standard functionalities with the implementation of specific external models constitutes a relevant contribution towards the development of a specific SDSS -MC in the environmental domain. The methodology includes the design of an interactive routine developed in Visual Basic in order to support the Screening/ Scoping, the Significance Evaluation, and Selection of the Environmental Indicators. The GIS functionalities are used to predict impacts and measure related indicators that are used as criteria, within the multicriteria analysis module, based on the ELECTRE III method. This will provide the user with a sorted list of possible alternatives, from the “most -environmental - friendly” down to the least. The methodology was applied to the case study of a motorway in the west -center of Portugal.