Water quality assessment in hydrographic watersheds in the extreme south of bahia, brazil

Abstract

This study aimed to evaluate the water quality of the Jardim and Mutari rivers, located in southern Bahia, by means of evaluating physical, chemical and microbiological parameters and land use and occupation. Four campaigns were carried out in April, May, July, and October, 2019, at 8 stations, selected according to possible punctual and diffusive sources of pollution. The water quality results were compared with that established by CONAMA n.º 357/2005and the Water Quality Index (IQA) was calculated from these. For data analysis, Principal Component Analysis (PCA) was also performed and Kruskal-Wallis tests were applied, using the PAST software.The land use and occupation analyses were performed using the QGIS software. We observed that the pH, OD, DBO, PT and NT were in disagreement with those allowed by the legislation, mainly near urban areas. The multivariate statistical analysis PCA, allowed to identify differences in the water quality of the watersheds in the dry and rainy period. The Kruskal-Wallis test indicated a significant difference between the environments analyzed.The supervised classification confirmed the need to recover areas along the riverbed within the analyzed micro-basins.Our results indicate it is crucial that public authorities act to minimize the impacts caused by the disorderly urban occupation and agricultural activities. It is also worth mentioning the importance of actions aimed at environmental education, mainly of the riverside population.