Avaliação da qualidade das águas superficiais da sub-bacia do rio Paracatu em função do uso e ocupação do solo

Abstract

Monitoring of surface water is an important activity for analysis of its quality, but it generates a very large and complex database that most often is underutilized. These databases provide important information on water quality when they are compiled and interpreted correctly. The analysis of the data generated during long-term monitoring programs reveals a tendency for elevation or reduction of the quality parameters and similarities between different monitoring sites. Often they result in an optimization of the monitoring program, and consequently a reduction in the costs of these programs. In this study, the objective was to relate the use and occupation of the land of the Paracatu river basin with the quality of surface water. The basin is evaluated in this study because of its the significance, being one of the most important river sub-basins of the São Francisco river, which is one of the most important rivers in Brazil. In this analysis, 34 parameters of water quality in 27 monitoring sites controlled by IGAM (Instituto Mineiro de Gestão das Águas) between 2006 and 2013 were evaluated. Statistical techniques, analysis of the violations of the parameters established by specific legislation and temporal analysis combined with information regarding demographics, sanitation, grants which have been awarded, licensed activities and thematic maps have allowed us to relate the water quality in the basin of the Paracatu river to the use and occupation of its land. These analyses have provided important information, such as the fact that the most common activity in the basin is agriculture. This activity has an impact on water quality, but not as much as the lack of sanitation in the cities of the basin, which ends up raising fecal coliform levels. Another activity that has impact in the basin is mining, which raises the arsenic levels at some monitoring sites. All the methodology used in this study produced congruent and complementary results, and corroborate the conclusion that land use has a direct impact on the quality of surface waters.