Hydrogeochemical assessment and spring water quality modelling along the Upper, Middle, and Lower Tyrrhenian Coast of the Calabria region, southern Italy

Groundwater, the main drinking source for over 2.8 billion people, meets more than half of global water needs. Effective management requires knowledge of its quantity and quality. This study analyzes 160 spring water points along Calabria's Tyrrhenian coast (southern Italy), divided into five sectors based on topographic, geological, and hydrogeological features. Physical-chemical parameters and hydrochemical facies were assessed using Langelier-Ludwig and Piper diagrams, supported by geostatistical tools. Results show significant variability. Waters in the Lao/Noce basins are “fairly to very hard” but “low mineral.” In the Upper Tyrrhenian, hardness and mineralization range from “low” to “average.” The Middle Tyrrhenian spans from “very light” waters over acidic rocks to “hard” waters over marble. The Lower Tyrrhenian is mostly “fairly hard,” while the Savuto Basin features “very light” to “light” waters, with minimal mineralization. Hydrochemical facies differ by area: Lao/Noce show chloride-sulphate and bicarbonate Ca-Mg types, influenced by agriculture. Upper Tyrrhenian waters vary with altitude. Middle Tyrrhenian springs in metamorphic rocks show lower Ca-Mg content. Lower Tyrrhenian waters reflect lithological diversity, while the Savuto shows nitrate contamination, indicating anthropogenic impact. This Mediterranean-representative area offers a reference for groundwater quality assessment and supports future comparative and sustainable management efforts.