Relações entre o uso e cobertura do solo e qualidade das águas na bacia do rio Jequitinhonha em Minas Gerais como subsídio à gestão dos recursos hídricos superficiais

Abstract

The Jequitinhonha river basin has been affected by changes in land cover and use impairing the quality of local water resources since the XVIII century, during the mining cycle of gold and diamond. The region is characterized by low rates of economic and social development, reduced rainfall, high temperatures, and low water availability in its hydrological regime. The Jequitinhonha river basin and its sub-basins have recent river basin plans, and limited implementation of water resources management instruments, as granting permits for the use of water and water usage charges. In this context, this work aims to relate the evolution of land cover and use in the basin to the water quality parameters components of the Water Quality Index (WQI), identifying the main sources of pressure on water resources. The classification of land cover and use was made using data provided by the MapBiomas Project in 2000 and 2014, while water quality data were obtained from the official monitoring program carried out by the Instituto Mineiro de Gestão das Águas - IGAM. Data analysis was conducted through descriptive statistical analysis and the construction of multiple regression models, using the variables of land use land cover as independent variables and water quality parameters (individually and IQA, in dry seasons and rainfall) as dependent variables. The regression model showed that the variables that obtained the most associations were Nitrate, Total solids and pH. Among the analyzed years, Coliformes Termotolerantes / E. Coli, Dissolved Oxygen, Turbidity and Total Solids the were not on compliance to the water framework thresholds. Agriculture or Pasture, Planted Forests, Urban Infrastructure, and Other non-forest formations showed expansion of its areas in the observed period. In this way, the deterioration of the environmental quality in the basin is highlighted, mainly due to the increase of areas with anthropic activities to the detriment of the reduction of natural areas, affecting water quality in the basin.