Disorderly urban expansion and unsustainable exploitation of natural resources threaten the balance of terrestrial ecosystems. Environmental pollution promotes climate change and accentuates events such as extreme floods and droughts. Studies indicate that pollution and deforestation in Critical Zones are the main factors that contribute to the development of socio-environmental problems, such as prolonged droughts, food supply and hydroelectricity crises. The State of São Paulo is the most populous in Brazil and highly susceptible to water crises. In this work, preliminary results are presented from a research that aims to integrate geophysical and hydrogeological data to characterize the underground water resources of a hydrographic microbasin located in a strategic area for São Paulo’s water supply. The first ERT and GPR profiles show promising results and suggest the occurrence of an unconfined aquifer system consisting of a thin regolith and a fractured crystalline rock.