Use of ground penetrating radar (GPR) for coastal aquifer characterization in Garopaba/SC

Abstract

The work analyzes the sedimentary deposits of the coastal aquifer of the locality of Limpa, Garopaba (SC), through geophysics and well data. A ground penetrating radar section (GPR) was acquired in an area adjacent to 4 wells located in the south of the municipality, provided by the water and sanitation company (CASAN). Three lithostratigraphic units were identified, with a basal layer composed of clayey material, an intermediate layer predominantly composed of sand representing the aquifer unit, and a superficial layer composed of fine sediments, peat and sand. The GPR section presents a paleochannel feature within the aquifer unit, showing the lateral variation of facies and depositional architecture within a lithological unit. The interpretation of key surfaces, textures and reflector termination patterns led to the diagnosis that the intercepted sedimentary deposits represent two depositional sequences, probably of Pleistocene age, composed by the record of lagoon-barrier and fluvio-estuarine systems. The lateral and vertical variation of sedimentary deposits has a significant influence on the hydrodynamic behavior of aquifers, so that the detailed scale characterization of the coastal aquifer can help the management of water resources, especially in areas extremely vulnerable to contamination and with high water demands, as is the case of Garopaba.