Avaliação histórica da qualidade da bacia representativa do rio Piabanha através de Índices de Qualidade da Água

Abstract

The motivating elements of this work are the problems in water bodies resulting from anthropic activities, mainly due to the use and occupation of soil in a basin, together with the difficulty of accessing water quality information. This study seeks to access water quality conditions in the representative basin of the Piabanha River through WQIs. The main objective is the temporal water quality assessment in this representative basin using the WQINSF used by INEA/RJ and the WQICCME. For the water quality evaluation, data from the EIBEX project were used, provided by SGB/CPRM, in the period from 2009 to 2017 and compared to data from INEA in the region's monitoring stations, Piabanha and Santo Antônio, for the same period. A Similarity was found in the WQIs values, for the EIBEX and INEA stations within period from 2013 to 2017. Comparatively, concerning the WQINSF obtained from the EIBEX stations, two stations resulted in the “medium” category, the preserved Rocio station and the Pedro do Rio control station (basin exutory); all urban (Esperança, Morin, and Liceu) and agricultural basins (Poço do Casinho, João Christ and Poço Tarzan), and control of Parque Petrópolis presented results for the average WQINSF, the “bad” category. Furthermore, the results of the WQICCME presented as a “bad” result Esperança and Morin; “Marginal” in Liceu, Parque Petrópolis and Pedro do Rio and “median” in Rocio, Poço do Casinho, João Christ and Poço do Tarzan. Results in the “bad” category of the WQINSF mean that the quality of the Piabanha River is far from desirable for public supply since this index focuses on this issue. The poor results of the WQICCME mean that water quality is almost always affected and that conditions always or almost always deviate from natural or desirable conditions in relation to the quality of class 2, which was used as a quality standard. Even the best stations, classified as “average” by the WQICCME, do not have the desired quality for their proposed uses. The WQICCME proved to be more appropriate because it allowed a greater number of campaigns to be included in the analysis, including a longer period of observation due to the absence of certain parameters for the WQINSF’s calculation. With the results of the individual parameters monitored in the EIBEX and from INEA, it became evident that the main source of pollution in the representative basin is sanitary effluents. This problem stems from the population increase in the region, which is not always reflected in the planning to improve the effluents’ treatment. There is even a need to improve the oversight of the ETPs’ operations by the environmental agency. For SGB/CPRM stations, some changes in monitored parameters were suggested, beyond changes in the location of some stations, also the data availability on the official portal. Concerning INEA monitoring, it was suggested that the frequency of campaigns be regular, besides the availability of all data on the portal, besides the review of the methodology for calculating the index about the phosphate and total phosphorus parameters.