Vulnerabilidade à contaminação das águas subterrâneas do município de Nova Palma, Rio Grande do Sul, Brasil/Contamination vulnerability of groundwater in the municipality of Nova Palma, Rio Grande do Sul, Brazil

While often imperceptible to the human eye, groundwater has a relevant role as a very important component of the hydrological cycle. This research presents a case study of the GOD system assessing the vulnerability of the aquifer to contamination. The study surveyed thirty-six groundwater extraction wells in the municipality of Palma Nova, registered and located on the edge of the Paraná Sedimentary Basin in the central region of Rio Grande do Sul, Brazil. Two aquifer systems occur in this area in both outcropping and confined zones; one is composed of volcanic flows known as the Serra Geral Aquifer System (SGAS) and the other of sedimentary sandstone rocks, known as the Guarani Aquifer System (SAG). The GOD method indicates that 8% of the wells are in the insignificant class of vulnerability, 15% in the low class, 31% in the moderate class, 31% in the high class and 15% in the extreme vulnerability class. Seven cemeteries and two gas stations were identified as pollution source points. These results could be used for land use planning by the municipality's administration as well as for the preservation of groundwater quality.