Contributions to the knowledge of the geohydraulic model and geothermal potential of the São Vicente Medical Spa aquifer system (Central Portugal)

Abstract

São Vicente Medical Spa is located in mainland Portugal (Southwest Europe) and has been using thermal waters for therapeutic purposes for a long time. The Romans were known to have used its sulphureous waters around 2000 years ago. The spa has a Roman bathhouse that is still visible today, and its ruins were discovered during recent excavations. In this work are presented some elements of the Roman baths, the current baths, as well as the main aspects of the thermal park, with the location of the sulphureous water abstractions, including the classic thermal spring, which discharges water at a temperature of 18.6 ºC. The geomorphological, geological, and hydrogeological aspects are outlined, giving particular attention to the water chemistry of the various abstractions to develop multiple applications of geothermometers to contribute to the knowledge of the geohydraulic model at depth and the geothermal potential of the aquifer system. The conclusions are drawn from a conceptual model, including the reservoir depth, which, according to various scenarios, will be between 3 km and 8 km, in a favorable situation, respectively, to reach groundwater with temperatures between 112 ºC and 118 ºC. Finally, some remarks are made about the location of the new groundwater abstraction and the depth to be reached to increase the exploitation flows and their temperature. Lastly, it outlined new studies to improve the current geohydraulic model and to investigate its relationship with the deep aquifer systems in its neighborhood, namely the Entre-os-Rios hydromineral system.