SENSORIAMENTO REMOTO ORBITAL E ANÁLISE DE TENDÊNCIA NAS MUDANÇAS DA COBERTURA E USO DA TERRA NO VALE DO SÃO PATRÍCIO AO LONGO DE QUATRO DÉCADAS

Abstract

The Brazilian Cerrado (Savanna) has undergone intense transformations in recent decades due to climate change, agricultural expansion, and socioeconomic pressures, which have triggered high levels of deforestation, resulting in significant changes in the land cover and in land use in the region. In this context, the Vale do São Patrício, a Cerrado region in Goiás State, Brazil, stands out for its agricultural and environmental importance, encompassing twenty-four municipalities, making it a strategic area for multitemporal analysis and monitoring of surface changes. This research aimed to evaluate the spatiotemporal dynamics of land cover in the Vale do São Patrício from 1985 to 2023 through orbital remote sensing. This study used the MapBiomas geospatial data product, including the 9.0 land cover data collection, based on Landsat satellite images with a spatial resolution of 30 m. Automatic image processing was carried out on the Google Earth Engine platform through cloud-based digital processing combined with the Random Forest algorithm. Annual thematic maps of surface changes over time were produced, allowing quantitative pixel-by-pixel extraction from the Land Use and Land Cover (LULC) product. The analyses included descriptive and dispersion statistics, the application of a nonparametric test, and the Mann-Kendall temporal trend test at a 5% significance level. Vegetation indices were also calculated to assess the spatiotemporal distribution patterns and quantitative variability of natural vegetation cover and agricultural areas. R (v.4.4.0) and QGIS (v.3.36) software were also applied for trend analysis and thematic maps production, respectively. The results showed a significant upward trend in agricultural-related classes, along with a reduction in native forests, with an average annual loss of 974.74 ha throughout the temporal analysis. This trend became particularly evident from the 1990s onward, reflecting the intensification of the agricultural occupation process. The Mann-Kendall test confirmed a significant upward trend (p-value<0.05) for agricultural areas, with annual gains of 1,046.52 ha for soybean and 2,345.31 ha for sugarcane. On the other hand, no significant trend was identified in pasture areas, showing signs of stability. Both Normalized Difference Vegetation Index (NDVI) and Soil-Adjusted Vegetation Index (SAVI) revealed the predominance of agricultural areas and the fragmentation of forest areas. SAVI was more sensitive for detecting bodies of water and areas of exposed soil. The intense transformation of the landscape in the Vale do São Patrício was driven by agricultural expansion at the expense of native vegetation. This dynamic intensifies environmental impacts, showing the area's increasing vulnerability and the need for sustainable territorial planning strategies. Remote sensing monitoring is needed to support the development of public policies focus on regional sustainability.