Origin, Age, and Flow Path of Groundwater Associated With High‐Mountain Springs in Arid Andean Regions

Abstract

Understanding groundwater recharge and flow dynamics in arid high-altituderegions is critical for effective water resourcemanagement under increasing climate and land-usepressures. Spring-fedsystems are hydrologically and ecologically important,yet remain poorly documented globally, and in the arid Andes they are particularly understudied, with available data beingscarce. This study aims to evaluate the residence time, recharge characteristics, and hydrochemical evolution of hydrogeologicalsystems associated with springs sustaining wetlands in the arid sector of the Andes, where mountain ranges reach elevationsof up to 6700 m a.s.l., within a complex geological-structuralsetting. Four spring-fedwetland systems in Argentina, spanningdiverse geological and structural settings, were analysed through the integration of isotopic (δ18O, δ2H, 3H), hydrochemical,and structural data. Fieldwork included geological mapping, in situ measurements of pH and electrical conductivity, and watersampling. Laboratory analyses encompassed major ion chemistry and stable isotopes. Hydrochemical facies were determinedusing Stiff diagrams, and statistical and isotopic methods were applied to assess recharge patterns and groundwater flow. Resultsindicate that spring waters are predominantly meteoric, reflecting mainly local recharge. Tritium concentrations (4.1–10.8 TU)suggest short residence times (< 15 years). Springs in siliciclastic formations exhibit higher tritium and deuterium excess values,consistent with recent recharge influenced by Atlantic-sourcedmoisture. Conversely, springs in volcanic and evaporitic unitsshow lower tritium and higher mineralisation, indicative of water–rock interaction and Pacific moisture influence rather thandeep regional flow. Structural features such as faults and fractures strongly control spring discharge locations and flow pathways.By combining isotopic and hydrochemical data with geological context, this study advances understanding of recharge andflow in high-altitudearid environments. In a broader regional and global perspective, these findings highlight similarities andcontrasts with other mountain systems, offering a transferable framework for managing fragile mountain water resources underchanging climatic conditions.