Spatial and temporal variation of water quality in a watershed in center-west Paraná, Brazil

Water quality monitoring is an essential strategy for water resources management. Physicochemical and microbiological parameters play an important role in the characterization of water quality. They are helpful tools for the identification of pollution in aquatic ecosystems, being natural sources or because of anthropogenic actions, and contribute to making decisions as well as sustainable development in a hydrographic basin. This study analyzed the water quality variation over a period of 20 years in Piquiri River watershed. Total phosphorus (TP) concentration from affluent rivers was estimated using a linear regression model. The relationship between total nitrogen and TP presented a Person’s linear correlation of 0.80, while turbidity and total suspended solids presented a correlation of 0.79. The relationship between the predicted and observed values for turbidity and TP presented r2 higher than 0.60. Spatial–temporal variation of water quality in Piquiri River watershed has shown good quality over the years, although unacceptable values for Escherichia coli, biochemical oxygen demand, chemical oxygen demand and total phosphorus levels appeared. Most unacceptable values were identified in affluent rivers, suggesting the improvement in the water quality closer to downstream of the Piquiri River. Water quality index also showed good quality water for all stations.