Fragilidade ambiental e dinâmica de uso e cobertura da terra na Bacia Hidrográfica do Ribeirão Forquilha (GO) - 1985 a 2023

Abstract

The study was conducted in the Ribeirão Forquilha Watershed, located in the Immediate Geographic Region of Ceres–Rialma–Goianésia. Covering an area of approximately 342 km², the watershed encompasses portions of the municipalities of Goianésia and Vila Propício. It is used for the public water supply of the former municipality and also constitutes an area of high agricultural potential. The objective of this study was to analyze the environmental fragility and the dynamics associated with land use and land cover from 1985 to 2023 in the aforementioned watershed. Initially, the watershed was characterized considering variables such as relief, soils, and rainfall, in addition to the temporal analysis of land use and land cover. For this purpose, databases from official institutions were used, including the Brazilian Institute of Geography and Statistics (IBGE), the Technical Assistance and Rural Extension Company (EMATER), and the Geological Survey of Brazil (CPRM), as well as terrain data derived from the 30 m Copernicus Digital Elevation Model (DEM), land use and land cover data from MapBiomas (1985–2023), and rainfall data from the CHIRPS product (2003–2023). Environmental fragility was assessed using adapted methodologies proposed by Jurandyr Luciano Sanches Ross (1994), Silvio Roberto de Oliveira Crepani et al. (2001), and Silva (2023). The integration of variables was performed through map algebra in a Geographic Information System (GIS) environment using the QGIS software. The results revealed significant changes in land use and land cover throughout the analyzed period. In 1985, pasturelands predominated (56.06%), whereas agriculture was scarcely represented (0.24%). By 2023, pasture areas had decreased to 38.70%, while agricultural areas increased substantially to 14.65%, mainly associated with soybean and sugarcane cultivation. Urban expansion in Goianésia was also noteworthy, increasing from 1.61% to 5.13% of the watershed area. Potential environmental fragility was predominantly classified as low (78.23%). In contrast, emergent environmental fragility was predominantly classified as medium, increasing from 56.59% in 1985 to 62.81% in 2023. Slope was found to play a significant role in differentiating potential environmental fragility, particularly in steeper areas, whereas soils and rainfall contributed less to this differentiation. On the other hand, land use and land cover emerged as the main controlling factor, highlighting the predominance of anthropogenic activities in shaping the environmental fragility of the watershed. Therefore, it can be concluded that the expansion of agricultural activities and urban growth are the main factors responsible for changes in the environmental fragility of the study area.