Temporal analysis of land cover and land use changes in a Brazilian Amazon urban watershed

Urban expansion has impacted watersheds that supply water to cities. This study analyzes land use and land cover changes from 1984-2023 in the Belém Metropolitan Region in Amazon Region, using Geographic Object-Based Image Analysis (GEOBIA) applied to Landsat imageries. Five land cover classes were mapped: lakes, aquatic macrophytes, urban areas, forest, and pasture. Results show a 13.4% increase in forest due to protected areas, a 3.7% reduction in lake surface area from macrophyte proliferation, and a 3.2% increase in urban expansion. Major transitions occurred in the boundaries of the watershed. The conversions of pasture to urban areas were most intense between 1984-1989, with 138.1 ha converted. The most significant land-use change in the study area was from pasture to forest, totaling 528 ha and to urban areas (274 ha) between 1984-2023. The overall accuracy of classification exceeded 88%. The study demonstrates GEOBIA’s effectiveness for long-term watershed monitoring using Landsat imagery. Mapping was successfully performed using Landsat imagery.The classifications presented overall accuracy rates above 88%.The most significant conversion was from pasture to forest.The conservation units have proven to be an excellent way to conserve the watershed.Human activity can jeopardize the health of the water sources of the BMR. Mapping was successfully performed using Landsat imagery. The classifications presented overall accuracy rates above 88%. The most significant conversion was from pasture to forest. The conservation units have proven to be an excellent way to conserve the watershed. Human activity can jeopardize the health of the water sources of the BMR.