Groundwater of Italy: hydrogeological mapping at 1:500,000 scale

This paper presents the Hydrogeological Map of Italy at a scale of 1:500,000 (CII500K). The map is organized into four sheets, accompanied by supplementary notes and tables, and complemented by an online version providing an updated and harmonized national overview of groundwater systems in Italy. The CII500K synthesizes the country's hydrogeological framework, describing groundwater distribution, recharge conditions, and use. It builds on recent regional cartographic studies and integrated datasets, adopting a unified methodology for defining hydrogeological complexes, relative permeability classes, and aquifer productivity. Developed through extensive GIS processing, including a WebGIS platform to promote a participatory work with technicians and researchers of different institutions, the map includes key thematic layers such as perennial freshwater tapped springs, thermal and coastal springs, piezometric contours, and major groundwater flowpaths. This cartographic product provides key information for sustainable water management and climate adaptation strategies consistent with European water policies.