Avaliação de variáveis físicas e de qualidade das águas em reservatórios de usinas hidrelétricas de Minas Gerais para gestão das águas no Estado

Abstract

Water is a natural resource of extreme importance, essential to the maintenance of life, besides being versatile, allowing multiple uses, such as water supply, navigation, irrigation, recreation, fish farming and electric power generation. The energy matrix of Brazil is predominantly of water origin, which prevails in the state of Minas Gerais. For the generation of energy, water courses are dammed, causing numerous modifications in the environment. The relevance of the reservoirs in the State generates attention to maintain energy production and water quality, which leads to the development of studies of these environments. Water quality monitoring, which is expensive and labor intensive, generates a large amount of data, which is often ignored. Statistics are a valuable tool in the treatment of these data, which enables them to be interpreted and applied in a practical way. Taking into account the importance of these bodies of water, as well as to interpret the monitoring data, the present work was based on the available information on reservoir water quality and physical characteristics, especially morphometry. The sample started with the 44 dams registered in the Water Quality Information System of the Reservoirs (Siságua) of Companhia Energética de Minas Gerais (Cemig), and later this number was reduced to twenty-nine reservoirs that have available information. The main objective of the study is to group (typify) reservoirs of hydroelectric power plants in Minas Gerais with similar characteristics, using statistics: Principal Component Analysis (PCA) and Similarity (cluster). The results showed that the most significant parameters were turbidity, conductivity, pH, transparency, BOD and total dissolved solids, and the most explanatory morphometric characteristics were area, perimeter, volume, residence time, drainage area, mean flow long period. There was a coincidence of part of reservoir groupings for the two analyzes, and the grouping regarding the variables of water quality was related to the geographic distribution of the environments. The work contributes to systematize, organize and order the management of these environments in the State.