ASSESSMENT OF URBAN EXPANSION IN ARARAQUARA/SP (1990–2020) BASED ON LANDSAT IMAGES: Impacts on Land Use and the Vulnerability of the Guarani Aquifer System

Abstract

The expansion of urban areas entails various environmental impacts, such as the suppression of vegetation, the disturbance of fauna and flora, as well as an increase in temperature. Surface and underground water resources are also affected, especially in the case of shallow aquifers, where soil impermeabilization reduces water recharge and increases the risk of contamination from diffuse sources. The municipality of Araraquara, located in the center of São Paulo State, has experienced accelerated urban area growth in recent decades. In this study, supervised classification of LANDSAT 5-TM and LANDSAT 8-OLI images was used to map land use and occupancy between 1990 and 2020. The results reveal a 43.71% increase in urban areas during this period, with an average growth rate of 0.59 km² per year. Spatial analysis indicates that urban expansion has already reached the boundary of the Guarani Aquifer System (GAS) outcrop area. If this expansion continues without adequate planning, there is an imminent risk of direct impacts on the GAS, including groundwater contamination and reduced water recharge. The results of this study indicate that any future expansion should be approached with caution, and it is essential that public policies and land-use planning strategies be implemented.