No abstract

The dissemination of information on water quality for a non-specialist audience is essential to support political and institutional actions for the management of aquatic environments. Therefore, water quality indices have been proposed since they are able to synthesize into a single value or category information, usually described from an extensive set of water quality variables. This research proposes a new water quality index, based on fuzzy logic, aimed at lotic environments, developed through the collaboration of experts in water quality of the Rio de Janeiro Environmental Agency (Instituto Estadual do Ambiente -INEA). The proposed index was applied to water quality data from the Paraíba do Sul River, obtained by INEA, in the years 2002 to 2009. The results of IQA FAL showed that the index was able to synthesize the water quality of this stretch of the Paraíba do Sul, satisfactorily matching the assessments of the water quality assessments contained in the reports available. It was also noticed that with this methodology it was possible to avoid the attenuation of the influence of a variable in critical condition was attenuated by the influence of other variables in favorable conditions, producing an inaccurate result in the final index.

The dissemination of information on water quality for a non-specialized audience is essential to support programs and institutional policies aimed at the management of aquatic environments. In order to represent the extensive set of variables used to describe the water quality, this set can be synthesized into a single value or category information by using water quality indices. This research compares the Fuzzy Water Quality Index for Lotic Environments-IQA FAL , a new index of water quality based on fuzzy logic, with the traditional water quality index developed by the United States National Sanitation Foundation-WQI. This new index was developed for lotic environments through the collaboration of water quality experts of the Rio de Janeiro Environmental Agency-FEEMA. Both indices were applied to water quality data from the Paraíba do Sul River, obtained by INEA (the State Environmental Institute of Rio de Janeiro), from 2002 to 2009 in addition to a set of simulated water quality data to compare their responses in specific scenarios. The comparison between the results obtained using both IQA FAL and WQI showed that only IQA FAL was sensitive to the influence of a bad condition in one isolated variable, even if the other variables were in good condition. Thus, the IQA FAL methodology allowed the development of an index able to avoid the attenuation of the influence of a variable in critical condition by the influence of other variables in good conditions.