Hydrogeological features of the Italian sources included within the European thermal-mineral water inventory developed after the H2020 GeoERA Hover project

Abstract

Italy is one of the richest countries in the world with regards to number and quality of thermal-mineral waters and has developed a widespread and extensive use of such resource (e.g. bathing, central heating, electric power production). Premised that, the Geological Survey of Italy (GSI) took part in a work package of the GeoERA Hover project (EU Horizon 2020 program under grant agreement N.731166) aimed at defining the interactions involving the geological asset and the hydrogeological processes with natural quality and contamination risk of groundwater and at building a geodatabase of thermal-mineral groundwater within an Information Platform at European level. The GSI activities also aimed at contributing to fill the lack of a comprehensive work dealing with a national scale hydrogeological picture of thermal-mineral waters in Italy. This paper shows the first results obtained with Hover Project on the definition of a general geologicalhydrogeological scenario of thermal-mineral occurrences at an Italian national scale (240 occurrences with cropping temperature >20°C have been included in a database). Most of exploited thermal-mineral water resources are aligned along the Tyrrhenian-Apenninic margin and in the Italian islands, where the most relevant active or quiescent geothermal fields related to magma ascent processes occur. As concerns physicalchemical features, extreme situations of over-mineralized and very-high temperature waters are not uncommon throughout Italy and correspond to a cluster of important SPA and geothermal field sites. Some preliminary geochemical considerations agree with mutual interaction between hydrothermal fluids rich in SO4-Cl-Na-K, likely originated from (ultra)potassic/calcalkaline/alkaline magmas, and HCO3/CO3-Ca waters, originated from leaching of calcareous rocks by groundwater. A preliminary statistical analysis on geochemical and other features of the Italian thermal-mineral sources on a regional basis envisaged that they do not display fully homogeneous characteristics.