Water quality index in an Urban Watershed

This study aimed to verify the water quality of Ribeirão das Pedras (Stones River), Campinas, São Paulo, Brazil through the implementation of the Water Quality Index (WQI) and comparison with Brazilian legislation (Resolution of the National Environment Council – CONAMA 357/2005), thus being able to initiate discussions about anthropic interferences in watercourses located in urban areas. Ribeirão das Pedras is part of an urban watershed that suffered, and still suffers, from the rapid and intense urban and housing boom, finding its territorial space almost fully occupied. For the execution of this work, six sample points were defined in order to allow a discussion between the land use within their respective drainage area and the results of the WQI applications. The WQI is composed of nine parameters: dissolved oxygen, biochemical oxygen demand, nitrogen, temperature, thermotolerant coliforms, turbidity, phosphorus, pH, and total solids. The first sample point refers to the main water-course source, four sample points are located throughout the watershed and the last point is located in its base level, at the confluence between Ribeirão das Pedras and its main stem, Ribeirão das Anhumas (Anhumas River). The results of water quality analysis obtained based on the WQI concept were featured as ‘GOOD’; however, the isolated analysis of each parameter allows to compare them with the Brazilian legislation, where it appears that none of the points meets all established quality parameters. Thus, it can be concluded that the watercourse suffers significant impacts along its course, probably derived from the use of the surrounding drainage areas.