Comparison between the index of biotic integrity and a method of multicriteria for analysis of the environmental quality of three streams tributaries to the of Itaipu reservoir

Abstract

The human activities have been exercising deep and, usually, negative influence on the water bodies. Some negative effects are due to the pollutant while others are associated to the hydrology changes of the basin, habitat modifications and energy sources alterations. In many situations the decision about the environmental involves selection of alternatives, events or actions. However, those decisions usually, have conflicting point of view and different judgments, forcing the researcher to decide without enough technical base and so, many times inducing wrong decisions. Based on the exposed above, the objective of this research was to present a multicriteria method (ELECTRE TRI) to evaluate the environmental quality of streams and to compare with the Index of Biotic Integrity (IBI); both methods were applied in tributaries of the Itaipu Reservoir (Ajuricaba, Arroio Fundo and Curvado rivers), using fish communities as indicator. According the results was verified that the choice of the multicriteria method for this type of study is valid, because when compared with the Index of Biotic Integrity the results were not so different. Besides, the ELECTRE TRI being a method that evaluates the criteria groups to classify the streams represents better the reality when compared with the Index of Biotic Integrity because it is a non-compensatory method.