Environmental impacts due to the behavior of limnological variables in water reservoirs of hydroelectric power plants

Reservoirs are artificial systems that alter the natural conditions of the environment. This transformation process affects the chemical, physical and biological properties of the water body. The objective of this study was to assess the environmental impacts due to the spatial behavior of limnological variables in water reservoirs, using the Espora Hydroelectric Power Plant (HPP) water reservoir as environmental system model. The parameters analyzed were: hydrogen potential (pH), water temperature, turbidity, transparency and chlorophyll-a content. Thirty-four collection points were selected in the model reservoir in four different periods (winter, spring, summer, and autumn). The results were compared to Brazilian legislation standards for fresh water, according to resolution no 357/2005 of the national council for the environment (Conama), and statistically evaluated through principal component analysis (PCA). The limnological parameters indicated that the water body can be classified as class 2. The first two axes of the PCA explain 62.59% of the total variation of the correlations among the physical, chemical, and biological variables, during the four sampling campaigns in the climatic seasons of the study cerrado region. Transparency, water temperature, pH, and chlorophyll-a content were the most significant variables, with correlation coefficients of 0.614, − 0.677, 0.755, and − 0.484, indicating a gradient related to the increase of the primary productivity of aquatic organisms in the reservoir. This work has useful results that can be used for the environmental monitoring of HPP water reservoirs around the world.