Land use and land cover dynamics and their effects on surface water quality in the Arroio Demétrio sub-basin, Gravataí (RS), Brazil
DOI:
https://doi.org/10.22456/1982-0003.154828Keywords:
Water Quality Index (WQI), Water quality parameters, Cartography, Water pollutionAbstract
The Demétrio Stream Watershed (DSW) is part of the Gravataí River Basin, in Rio Grande do Sul, southern Brazil, and encompasses portions of the municipalities of Taquara and Gravataí. The study area is characterized by a predominance of rural areas, with a marked expansion of eucalyptus plantations, whereas its southern sector has undergone intense urbanization. Considering the importance of the Demétrio Stream as the main tributary of the Gravataí River, this study aimed to assess water quality at three monitoring sites within the sub-basin. Three sampling campaigns were conducted in May 2023, January 2024, and February 2024 under different hydrological conditions. The methodology included laboratory analysis of water samples, preparation of land use and land cover maps for 1986 and 2022, and a literature review. Water quality was assessed using the Water Quality Index (WQI) adopted by the Environmental Company of the State of São Paulo (CETESB, in Portuguese) and the Minas Gerais Institute for Water Management (IGAM, in Portuguese). The results indicated good water quality at Site 1 (mean WQI = 70), between good and fair at Site 2 (mean WQI = 62), and between fair and poor at Site 3 (mean WQI = 50). According to CONAMA Resolution No. 357/2005 (Brasil, 2005), Site 1 was predominantly classified as Class 1, Site 2 between Classes 2 and 3, and Site 3 between Classes 3 and 4. These findings demonstrate that water quality indices, combined with land use and land cover analysis, provide an effective tool for environmental assessment and planning in the DSW.
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Copyright (c) 2026 Luiz Fernando Alves

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Accepted 2026-07-07
Published 2026-07-30

