Isabel Rodrigues da Rocha
Abstract:
In recent years, there have been many hydroelectric projects installed in several rivers in Brazil. Energy production from reservoirs of hydroelectric plants is responsible for over 90% of the energy consumed in the country by urban centers (ANEEL, 2005). Thus, in Goiás state, between Caçu and Cachoeira Alta cities, the Caçu Hydroelectric Power Plant (UHE) reservoir, located in Rio Claro watershed, southwest of the state, is the object of study. Thus, this study aimed to analyze the water quality of the Caçu UHE reservoir in two distinct climatic periods of the Brazilian Cerrado. It also aimed to classify the reservoir water body according to the standards recommended in CONAMA Resolution N. 357, 2005, for some physical and chemical limnological characteristics, such as: electrical conductivity, dissolved oxygen, pH (Hydrogen Potential) , water temperature, total dissolved solids and turbidity, collected in four temporal campaigns. The study periods ranged from January 2012 to July 2013, covering the different rainy (water surplus) and dry (water deficit) climatic periods of rainfall in the Caçu UHE reservoir environment. Land use was evaluated to know the physical and environmental characteristics of the Caçu UHE basin, by analyzing the main occupations of vegetation, pasture, culture and forestry, for the rainy and dry periods of 2013, in order to verify the preservation of the riparian forests. Water analyzes were evaluated with the Oakton Pcd 650 multiparameter probe and turbidimeter. Data mappings and georeferencing were carried out with the support of SPRING 5.1.7 and ArcGIS 10.1 software, for the location, land use, slope, geology, geomorphology, soils and distribution of limnological variables. The results obtained from the water analysis were discussed and compared based on CONAMA Resolution N. 357, of March 17, 2005, fitting the freshwater classes. In this sense, the results were evaluated for compliance with the limits, verifying points that fall into Classes 1, 2 and 3; Only a few points presented in class 4, considered more rigorous. Current quality conditions showed good statistical analysis. The most significant correlations occurred in the case of electrical conductivity (CE) and total dissolved solids (TDS) with r = 0.96. The best correlations are directly related to the amount of dissolved ions and water temperature.
