Hudson Moraes Rocha
Abstract:
Hydraulic projects, such as dam construction, profoundly interfere with the characteristics of the sites where they are installed, as they influence the physical, chemical and biological properties that are fundamental to the functioning of ecosystems. The Barra dos Coqueiros Hydroelectric Power Plant (UHE) is located in the lower course of the Rio Claro, in the municipality of Caçu, southwest of Goiás state, and has been in operation since January 2010. The present work aimed to analyze spatially and temporally the physical and chemical characteristics of the tributaries water, and the Barra dos Coqueiros UHE reservoir, in order to identify factors that interfere with water quality from September 2010 to August 2011. The studied limnological parameters were: water temperature, potential hydrogenic acid, electrical conductivity, total dissolved solids, salinity, resistivity and turbidity. The methodology applied for physicochemical water analysis follows the procedures of the US Federative Association of Water and Environment. According to the evaluated data, it can be concluded that the tributaries that present inadequate hydrogenic potential and electrical conductivity parameters were the left bank Coconut Palm tributary, which supplies material from the alteration and erosion of the Marília Formation rocks, and the tributary do Vau, which supplies material from the alteration of rocks of the Vale do Rio do Peixe Formation. The parameters found in these two tributaries are outside the standard accepted by Resolution N. 357/05, however, the other samples are in accordance with the legislation. In the rainy season, the turbidity values for the tributaries of the Barra dos Coqueiros watershed are more different than in the dry period, with emphasis on the left bank Coqueiro tributary and the Vau tributary. The best correlations of limnological measurements were found for parameters that are directly related to the amount of ions present in water, such as hydrogen potential, electrical conductivity, total dissolved solid, sodium chloride and resistivity. The water sections of the Barra dos Coqueiros UHE reservoir that presented the highest values of the physicochemical parameters are upstream of the reservoir, with the smallest cross-sections and the highest water flow velocities. The reservoir waters, according to CONAMA Resolution N. 357/2005 for the studied parameters, are included in classes 1, 2 and 3, that is, waters considered fit for human consumption. It's recommended for the Barra dos Coqueiros UHE basin: a) the preservation and increase of riparian forest to serve as ecological corridors; (b) revegetation of the drainage channel margins to minimize the effects of erosion; c) Soil conservation near the Barra dos Coqueiros basin to avoid the siltation effects of this water segment; d) Finally, the creation of ecological corridors to establish connectivity between isolated fragments, minimizing the risks of biodiversity loss.
