Avaliação da influência do regime hidrológico sobre aqualidade das águas em cursos dágua do Estado deMinas Gerais

Abstract

Anthropogenic activities in watersheds are responsible for significant impacts on the quantitative and qualitative characteristics of rivers, such as increased flows during the wet season and reduced flows during the dry season, discharge of effluents into the water and leaching by runoff. It is known that the hydrological regime, through its periods of rain and drought, has great influence on water quality, and that the issues related to the variation of this quality has a great complexity. This fact motivated the present work aims to characterize and evaluate the influence of hydrological regime, during the wet and dry seasons, on the quantitative and qualitative aspects of some rivers of the State of Minas Gerais, located in regions with more and less water availability. For this research were used the quantitative information available at Agência Nacional das Águas, and qualitative information available at Instituto Mineiro de Gestão das Águas, both information of Verde and Aiuruoca rivers, located in the south of the State and considered representatives of the region with more water availability, and Mucuri and Araçuaí rivers, located further north of the State and considered representatives of the region with less water availability. Through statistical analysis for the qualitative and quantitative information observed that, in general, the variation of the medians of dry and wet seasons, between regions with more and less water availability, has different behavior for the data series of fecal coliform, electrical conductivity and total dissolved solids. Stations in the south of the State, the significance level of 5%, the median series of fecal coliform and total dissolved solids are not significantly different, and the median of the series of electrical conductivity are significantly different, and at stations further north of the State the medians of these quality parameters have opposite behavior. Considering the periods established as dry and wet seasons, this study indicate that the rivers with less water availability, located north of the State, there is a further degradation of water quality during the wet season than in the rivers with more availability water located in the south of the State.