Da nascente à ocupação: levantamento de uso e ocupação na Bacia Hidrográfica do Riacho Bacuri, em Timon - MA.

Abstract

The accelerated process of urbanization observed in recent decades has caused significant transformations in spatial organization and in the dynamics of natural systems, especially in transition areas between urban and rural zones. In this context, watersheds stand out as fundamental units for integrated analysis, as they encompass, within a single territorial framework, the interactions among relief, soils, vegetation cover, drainage networks, and anthropogenic land use. The Bacuri stream watershed, located in the municipality of Timon, Maranhão, has been subjected to intense anthropic pressures resulting from unplanned urban expansion, suppression of native vegetation, and the lack of effective territorial planning instruments, leading to a scenario of increasing environmental vulnerability. Given this context, the present study aimed to diagnose land use and land cover in the Bacuri stream watershed and to analyze vegetation cover dynamics between 2020 and 2024, using remote sensing, geoprocessing techniques, and field validation. The methodology was structured into sequential stages, including the collection and processing of spatial data from the MapBiomas platform, the production of thematic land use and land cover maps, the application of the Normalized Difference Vegetation Index (NDVI) based on Landsat satellite imagery, and on-site field surveys to validate and complement spatial analyses. The results indicate a significant reduction in natural formations and native vegetation, associated with the fragmentation of remaining Cerrado areas and a marked expansion of urbanized and exposed-soil areas, particularly near access roads and in locations previously occupied by continuous vegetation cover. Comparative NDVI analysis reinforced the trend of loss of photosynthetically active vegetation throughout the analyzed period, while field observations identified processes of vegetation suppression, burnings, improper solid waste disposal, expansion of land subdivisions, and alterations in the hydrological dynamics of the stream. It is concluded that the Bacuri stream watershed presents a high degree of environmental vulnerability, directly resulting from real estate pressure and territorially unplanned occupation. The data and analyses produced in this study provide relevant technical support for environmental and territorial management in the municipality, contributing to sustainable watershed planning and to the formulation of public policies aimed at natural resource conservation and land-use regulation.