Evaluation of the Trophic State Index and water quality parameters in the reservoir of the Sá Carvalho Hydroelectric Power Plant, Minas Gerais, Brazil

Abstract

The aim of this study was to evaluate the influence of soil use on the water quality of the reservoir of the Sá Carvalho Hydroelectric Plant (UHE-Sá Carvalho, acronym in Portuguese), Antônio Dias municipality, Piracicaba River Basin (BHRP, acronym in Portuguese), Minas Gerais, Brazil. Secondary data were obtained from the reports of the Environmental Research Laboratory of Companhia Energética de Minas Gerais (CEMIG), in the dry season (August) and rainy (November). In this context, points were selected for collecting water samples from the reservoir, which represented different conditions in relation to depth. Physicochemical parameters were measured: temperature, dissolved oxygen, electrical conductivity, pH, total nitrogen, total phosphorus, turbidity and total dissolved solids. The results showed seasonal variation, and the relevance of the contribution basin was detected. In addition, they showed significant differences in collection points closer to the top of the reservoir compared to those located at the bottom of the reservoir. The environmental variables showed significant oscillations, with turbidity varying between 88.6 NTU and 3.6 NTU in the rainy and dry seasons, respectively. The reservoir showed good conditions for dissolved oxygen contents during the entire sampling period. The minimum value was 7.6 mg/LO2 in the dry season and 4.4 mg/LO2 in the rainy season. This approach is concluded by suggesting intensification of conservation programs in the reservoir and the contribution basin.