Qualidade da água em área de preservação ambiental: estudo de caso em Viçosa-MG

Abstract

The relentless pursuit of well-being and the demands created by human needs drive people to inhabit and expand their presence into the most inhospitable areas of our planet, often without assessing the consequences and thereby jeopardizing the ecological foundations of their livelihoods. In the Zona da Mata Mineira region, particularly in the city of Viçosa, the availability of water for human consumption has been a recurring issue. The Ribeirão São Bartolomeu watershed serves as a significant source of water for public supply. The region where the basin is located features extensive areas of steep slopes and intensive land use, potentially contributing to reduced water infiltration and increased sediment transport into water courses. Due to its environmental significance, the basin was designated as an Environmental Protection Area (EPA) in 2017. Considering a watershed as a strategic management unit for water resources, and EPAs as areas endowed with abiotic, biotic, aesthetic, and cultural attributes, the present study aims to diagnose and analyze water quality in the Ribeirão São Bartolomeu EPA in Viçosa, Minas Gerais, in light of land use and occupation dynamics and the demand for water resources by the local population. To assess water quality, the Water Quality Index (WQI) was calculated based on the methodology used by the São Paulo State Environmental Company and compared to the limits established in CONAMA Resolution No. 375/2005. Field campaigns and analyses were conducted from May 2023 to September 2024. Vector data (shapefiles) and additional information on the physical environment's properties were downloaded from official databases. Land use and occupation maps were produced and interpreted for the years 1993 and 2023. The results indicated that the water quality of the streams within the São Bartolomeu EPA generally met the requirements of current legislation. However, bacteriological analysis of Escherichia coli (E. coli) in the São Bartolomeu stream revealed levels exceeding the legal thresholds. Water quality in the EPA was rated as fair in 64.8% of the samples collected, poor in 17.6%, and good in 17.6%. A key finding regarding land use was a 63% increase in arboreal vegetation within the EPA between 1993 and 2023, despite significant fragmentation caused by the expansion of condominiums and residential subdivisions. The literature highlights a reduction in streamflow, even as precipitation volumes remain unchanged. The main conclusions suggest that anthropogenic interference can affect the São Bartolomeu EPA system, leading to reduced streamflow, water contamination, and a decline in WQI.