Hydrogeochemical tools applied to the study of carbonate aquifers: examples from some karst systems of Southern Spain

Abstract

Karst aquifers present hydrogeological characteristics that distinguish them from others such as fractured and granular aquifers. In particular, they are characterized by highly heterogeneous functioning (large temporal and spatial variability), which makes difficult the application of traditional research methods to karst hydrogeology. For this reason, during the last decades, hydrogeochemical tools have been developed for carbonate aquifers characterization by means of spatial and temporal hydrochemical variability, mixing processes (recharge vs. stored water in the system), groundwater origin (saturated/unsaturated zones, epikarst, etc.), karstification degree and, in general, the hydrogeological functioning of karst aquifers. In the present work, some of the most used techniques to study this type of media are applied to pilot sites from South Spain, in order to show hydrogeochemical processes related to karst aquifers functioning: groundwater origin, distribution of its chemical composition, aquifer behavior, water residence time, substratum influence and geochemical modelling. The results display that the combination of different hydrogeochemical tools provides a comprehensive understanding of the functioning of karst systems, which is useful for groundwater management and protection as well as for environmental applications (groundwater ecodependent systems, wetlands, coastal aquifers, etc).