INTEGRATED ESTIMATION OF GROUNDWATER RESOURCES VULNERABILITY IN THE URBAN CORE OF VISCONDE DE MAUÁ (RJ): APPLICATION OF GEOPHYSICAL METHODS IN THE SERRA DA MANTIQUEIRA ENVIRONMENTAL PROTECTION AREA AND IMPLEMENTATION OF AN ADAPTED METHODOLOGY

This study aimed to assess the natural vulnerability of groundwater resources through the adaptation of the EKv methodology, combined with physical characterization of the soil and geophysical techniques (GPR, electrical resistivity, and magnetometry), applied in a site lacking pre-existing local hydrogeological data, in Visconde de Mauá–RJ, Brazil. The EKv method considers the thickness (E) and vertical permeability (Kv) of the unsaturated zone, enabling an integrated analysis of the aquifer’s natural protective capacity. The results indicated three vulnerability classes: medium in Campo do Centro (EKv = 7), medium in Praça da Igreja (EKv = 5), and high in Lote-10 (EKv = 8). Low clay content, geologic structures favorable to vertical percolation, and the reduced thickness of the unsaturated zone were key factors in limiting the natural attenuation capacity. The presence of lithological contacts, sub-horizontal foliation, and fractures increases the contamination risk by promoting preferential flow paths. The integrated approach proved effective in identifying critical vulnerability zones, despite the limitations of the EKv methodology. The incorporation of geophysical methods significantly improved the accuracy of estimations and contributed to a more detailed spatial analysis of the subsurface, providing more robust support for the assessment of groundwater vulnerability.