Towards a better understanding of the Oulmes hydrogeological system (Mid-Atlas,Morocco)

Located in the Mid-Atlas (Morocco), the Oulmes plateau is famous for its mineral water springs “Sidi Ali” and “Lalla Haya” commercialised by the company “Les Eaux minérales d’Oulmès S.A”. Additionally, groundwater of the Oulmes plateau is intensively exploited for irrigation. The objective of this study, essentially performed from data collected during isotopic (summer 2004) and piezometric and hydrogeochemical field campaigns (spring 2007), is to improve the understanding of the Oulmes hydrogeological system. Analyses and interpretation of these data lead to the statement that this system is constituted by a main deep aquifer of large extension and by minor aquifers in a perched position. However, these aquifers interact enough to be in total equilibrium during the cold and wet period. As highlighted by isotopes, the origin of groundwater is mainly infiltration water except a small part of old groundwater with dissolved gas rising up from the granite through the schists.     

Hydrogeological controls of variable microbial water quality in a complex subtropical karst system in Northern Vietnam

Karst aquifers are particularly vulnerable to bacterial contamination. Especially in developing countries, poor microbial water quality poses a threat to human health. In order to develop effective groundwater protection strategies, a profound understanding of the hydrogeological setting is crucial. The goal of this study was to elucidate the relationships between high spatio-temporal variability in microbial contamination and the hydrogeological conditions. Based on extensive field studies, including mapping, tracer tests and hydrochemical analyses, a conceptual hydrogeological model was developed for a remote and geologically complex karst area in Northern Vietnam called Dong Van. Four different physicochemical water types were identified; the most important ones correspond to the karstified Bac Son and the fractured Na Quan aquifer. Alongside comprehensive investigation of the local hydrogeology, water quality was evaluated by analysis for three types of fecal indicator bacteria (FIB): Escherichia coli, enterococci and thermotolerant coliforms. The major findings are: (1) Springs from the Bac Son formation displayed the highest microbial contamination, while (2) springs that are involved in a polje series with connections to sinking streams were distinctly more contaminated than springs with a catchment area characterized by a more diffuse infiltration. (3) FIB concentrations are dependent on the season, with higher values under wet season conditions. Furthermore, (4) the type of spring capture also affects the water quality. Nevertheless, all studied springs were faecally impacted, along with several shallow wells within the confined karst aquifer. Based on these findings, effective protection strategies can be developed to improve groundwater quality.     

Monitoring groundwater in the discharge area of a complex karst aquifer to assess the role of the saturated and unsaturated zones

The hydrochemical response at springs in the drainage area of the Sierra del Rey—Los Tajos carbonate aquifer (province of Málaga, southern Spain) was monitored in order to determine the hydrogeological functioning of this aquifer. Analysis of the most important chemical parameters, using methodologies such as the temporal evolution of chemical components, principal component analysis and discriminant factorial analysis revealed that the high level of hydrochemical heterogeneity to be found in this discharge zone, in addition to particular spatial and temporal factors, is responsible for the mineralisation of the spring water. Sampling in karst systems where discharge occurs by several springs should take into account the hydrochemical variability of them; otherwise conclusions about the hydrological functioning of aquifers deduced from mixture of spring waters can be inaccurate.     

The regional park of the Nebrodi Mts. (Sicily): a contribution to an integrated groundwater management

 The Nebrodi Park, located in the north-eastern sector of Sicily, is of particular environmental and scientific interest. This is due to the morphological heterogeneity of the protected region that presents a wide variety of landscapes and ecosystems. In spite of the recent efforts of the Regional Government and Municipalities, environmental resources, especially groundwater, risk progressive depauperation and pollution. In this paper, the authors consider the hydrogeological karst unit of Monte Traura-Rocche del Crasto, the most productive in the Nebrodi belt (zone B of the regional park). This unit is underexploited and needs a careful hydrogeological study in order to supply coastal aquifers. Geochemical and geophysical prospecting has been carried out in this area. Analyses of water springs, sampled in different seasons, have suggested patterns of groundwater circulation. Apparent resistivity measurements have yielded complementary information about the recharge processes of deep aquifers. Goals of the project to which this research belongs are the rational exploitation and protection of reservoirs such as Monte Traura and the recovery of the degraded aquifers, proposing new strategies of regional management for the water resources in this comer of Sicily. Received: 27 November 1996 · Accepted: 5 January 1998     

Balneological study based on the hydrogeochemical aspects of the sulfate springs water (Hit–Kubaiysa region), Iraq

This research examined the balneological characteristics of spring waters within the area of Abu-Jir Fault Zone throughout the hydrogeologic aspects explained by the setting of the hydrogeologic units including the water-bearing horizons of Euphrates, Ana, and Baba Formations. The groundwater flow in the hydrogeologic system correlated with the trends of enrichment or depletion case processes of mineralization (spatial distribution maps of TDS and other components) show different phenomena of groundwater source and interconnection, which helps in the classification springs into two potential site. The physicochemical characteristics of the water flow from springs indicate a hydrochemical approach throughout the spatial variation of important parameters (using Rockware software) related to the balneological study. The monitoring network of the spring waters performed by seven field measurements and 33 variables (totaling to 720 detected measurements) in 18 springs approved the after desk study and water point inventory using a GPS apparatus (GARMIN SUMMIT-e TREX). The study examined the integrated hydrogeological aspects and spring water properties for evolutions and the classification of minero-medicinal water. The traditional hydrochemical information of the spring waters and their sediment properties correlated with balneological limits (standards and definitions) are used in the selection of springs characterized by balneotherapeutic applications. A suggested screening and ranking technique has been developed for evaluating preferable springs selected for natural therapy. The application of ranking technique indicates four graded consequent preferable springs for balneotherapeutic investment: first grade spring represented by Kubaiysa spring (S-4); second grade springs represented by Tawila spring (S-12); third grade springs represented by Mamora spring (S-15), Arnab spring (S-10), Zazoe spring (S-5), and Maqtoom spring (S-13); and fourth grade springs represented by Khalidiya spring (S-16) and Layeg spring (S-7).     

Roles of hydrogeochemical evaluations in estimating protection zones of Koçpınar springs in Aksaray, central Anatolia, Turkey

The present study indicates estimation of protection zones of KoçpLnar springs in Aksaray area by means of hydrogeochemical methods. Relevant hydrogeochemical studies were carried out to achieve this objective. KoçpLnar springs emerge on strike-slip Hasanda<L fault set (HFS) along the Tuzgölü (Salt Lake) fault zone (TFZ) in central Anatolia. The outcrops of volcanic origin exhibit different hydrogeological properties in the study area. The hydrogeochemical evaluations of KoçpLnar springs represent good results about the available main groundwater flow systems that exist in this area. Marbles of Palaeozoic age form the main aquifer that recharges KoçpLnar springs. The CO₂ gas content of the spring waters is significantly high. Based on the ion concentrations, the water of this spring has mainly two hydrochemical facies: Ca-Mg-HCO₃ and Na-HCO₃. Although, the hydrochemical analyses showed that waters of these springs meet the drinking and irrigation water standards, the area around the springs is continuously being contaminated by both domestic and agricultural wastes. Therefore, detailed hydrogeological, hydrochemical and isotopic investigations were carried out to accurately estimate the protection zones of KoçpLnar springs. These studies showed that three main protection zones could be proposed against external pollution effects around the spring's area.     

Using non-conservative tracers to characterise karstification processes in the Merinos-Colorado-Carrasco carbonate aquifer system (southern Spain)

The systematic sampling of the chemical composition of the groundwater from five karst springs (including an overflow spring) and one outflowing borehole have permitted to determine distinctive chemical changes in the waters that reflect the geochemical processes occurring in a carbonate aquifer system from southern Spain. The analysis of the dissolution parameters revealed that geochemical evolution of the karst waters basically depends on the availability of the minerals forming aquifer rocks and the residence time within the aquifers. In the three proposed scenarios in the aquifers, which include the preferential flow routines, the more important geochemical processes taking place during the groundwater flow from the recharge to the discharge zones are: CO₂ dissolution and exsolution (outgassing), calcite net dissolution, calcite and dolomite sequential dissolution, gypsum/anhydrite and halite dissolution, de-dolomitization and calcite precipitation. A detailed analysis of the hydrochemical data set, saturation indices of the minerals and partial pressure of CO₂ in the waters joined to the application of geochemical modelling methods allowed the elaboration of a hydrogeochemical model of the studied aquifers. The developed approach contributes to a better understanding of the karstification processes and the hydrogeological functioning of carbonate aquifers, the latter being a crucial aspect for the suitable management of the water resources.     

Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine,Arizona (USA)

The processes that affect water chemistry as the water flows from recharge areas through breccia-pipe uranium deposits in the Grand Canyon region of the southwestern United States are not well understood. Pigeon Spring had elevated uranium in 1982 (44 μg/L), compared to other perched springs (2.7–18 μg/L), prior to mining operations at the nearby Pigeon Mine. Perched groundwater springs in an area around the Pigeon Mine were sampled between 2009 and 2015 and compared with material from the Pigeon Mine to better understand the geochemistry and hydrology of the area. Two general groups of perched groundwater springs were identified from this study; one group is characterized by calcium sulfate type water, low uranium activity ratio ²³⁴U/²³⁸U (UAR) values, and a mixture of water with some component of modern water, and the other group by calcium-magnesium sulfate type water, higher UAR values, and radiocarbon ages indicating recharge on the order of several thousand years ago. Multivariate statistical principal components analysis of Pigeon Mine and spring samples indicate Cu, Pb, As, Mn, and Cd concentrations distinguished mining-related leachates from perched groundwater springs. The groundwater potentiometric surface indicates that perched groundwater at Pigeon Mine would likely flow toward the northwest away from Pigeon Spring. The geochemical analysis of the water, sediment and rock samples collected from the Snake Gulch area indicate that the elevated uranium at Pigeon Spring is likely related to a natural source of uranium upgradient from the spring and not likely related to the Pigeon Mine.     

Compositional multivariate statistical analysis of thermal groundwater provenance: A hydrogeochemical case study from Ireland

Thermal groundwater is currently being exploited for district-scale heating in many locations world-wide. The chemical compositions of these thermal waters reflect the provenance and circulation patterns of the groundwater, which are controlled by recharge, rock type and geological structure. Exploring the provenance of these waters using multivariate statistical analysis (MSA) techniques increases our understanding of the hydrothermal circulation systems, and provides a reliable tool for assessing these resources.Hydrochemical data from thermal springs situated in the Carboniferous Dublin Basin in east-central Ireland were explored using MSA, including hierarchical cluster analysis (HCA) and principal component analysis (PCA), to investigate the source aquifers of the thermal groundwaters. To take into account the compositional nature of the hydrochemical data, compositional data analysis (CoDa) techniques were used to process the data prior to the MSA.The results of the MSA were examined alongside detailed time-lapse temperature measurements from several of the springs, and indicate the influence of three important hydrogeological processes on the hydrochemistry of the thermal waters: 1) salinity and increased water-rock interaction; 2) dissolution of carbonates; and 3) dissolution of sulfides, sulfates and oxides associated with mineral deposits. The use of MSA within the CoDa framework identified subtle temporal variations in the hydrochemistry of the thermal springs, which could not be identified with more traditional graphing methods, or with a standard statistical approach. The MSA was successful in distinguishing different geological settings and different annual behaviours within the group of springs. This study demonstrates the usefulness of the application of MSA within the CoDa framework in order to better understand the underlying controlling processes governing the hydrochemistry of a group of thermal springs in a low-enthalpy setting.     

Hydrogeochemistry and isotope techniques to determine water interactions in groundwater-dependent shallow lakes,Wet Pampa Plain,Argentina

This paper gives an account of the implementation of hydrochemical and isotopic techniques to identify and explain the processes that govern solute exchange in two groundwater-dependent shallow lakes in the Southeastern Pampa Plain of Argentina. Water samples (lakes, streams, spring water and groundwater) for hydrochemical and stable isotopic determination were collected and the main physical–chemical parameters were measured. The combination of stable isotope data with hydrogeochemical techniques was used for the identification of sources and preferential recharge areas to these aquatic ecosystems which allowed the explanation of the lake water origin. The hydrochemical processes which explain Los Padres Lake water chemistry are evaporation from groundwater, CO₂ input, calcite dissolution, Na⁺ release by Ca²⁺ and Mg²⁺ exchange, and sulfate reduction. The model that best aligns with La Brava Lake hydrochemical constraints includes: mixing, CO₂ and calcite dissolution, cationic exchange with Na⁺ release and Mg²⁺ adsorption, and to a lesser extent, Ca/Na exchange. This model suggests that the fractured aquifer contribution to this water body is greater than 50 %. An isotopic-specific fingerprint for each lake was identified, finding a higher evaporation rate for La Brava Lake compared to Los Padres Lake. Isotopic data demonstrate the importance of these shallow lakes as recharge areas to the regional aquifer, becoming areas of high groundwater vulnerability. The Tandilia Range System, considered in many hydrogeological studies as the impermeable bedrock of the Pampean aquifer, acts as a fissured aquifer in this area, contributing to low salinity waters and with a fingerprint similar to groundwater isotopic composition.     

Hydrochemistry and isotope geochemistry as tools for groundwater hydrodynamic investigation in multilayer aquifers: a case study from Lomellina, Po plain, South-Western Lombardy, Italy

A multicriteria approach in studying hydrodynamics of a multilayer aquifer system has been used in the Lomellina region (Northern Italy). It involves the reconstruction of the hydrogeological framework coupled to the definition of the hydrochemical and isotopic features of the aquifers. A shallow phreatic aquifer, reaching depths of about 60–80 m from the surface, and deeper aquifers containing confined groundwater, were distinguished. Groundwater generally shows mineralisation decreasing with depth; dissolved ions depict calcium-bicarbonate hydrochemical facies and stable isotopes define the recharge mechanisms, the origin of groundwater, and the hydraulic confinement of deep aquifers. The phreatic aquifer is fed by local infiltration and by streams and irrigation channels. Tritium and Carbon-14 groundwater dating indicate long residence times (on the order of thousands of years) for confined aquifers. The confined aquifers show essentially passive hydrodynamic conditions and maintain a higher piezometric level than the phreatic aquifer. This inhibits the possibility of recent water penetrating far below the surface. The hydrogeological setting of the Lomellina region displays features which are common to other sectors of the Po plain. As a consequence, the results of this study, although conducted on a restricted area, are highly illustrative of groundwater hydrodynamics in large sedimentary aquifers.     

Hydrogeological and hydrochemical features of an area polluted by heavy metals in central Nicaragua

Geophysical and hydrochemical surveys were used to investigate the hydrogeological conditions in one of the Río Sucio microbasins, in central Nicaragua. Zones of vertical structures (i.e. fractures and quartz veins) and weathering were mapped using Continuous Vertical Electrical Soundings (CVES), as such zones are of major importance for groundwater transport. Water from the springs was analysed to determine concentrations of major ions and heavy metals. Low ion concentrations and ¹⁸O analyses indicate that the springs occur close to their recharge areas and there is a relatively rapid groundwater circulation. Mercury (Hg) content in the springs was low, while comparatively high amounts of lead (Pb) were found. The results presented here demonstrate the important function of weathering and tectonics in the occurrence of groundwater systems in the basin. Hg and Pb found in the springs’ water reveal the existence of an increase in pollution sources disseminating in the area. More than 100 years of using mercury in the gold-mining industry and releasing wastes into rivers has affected water quality and ecosystems. Further investigations are needed in this area to determine the groundwater vulnerability to this pollution as this resource may be needed in the future.     

Stable isotope (2H, 18O and 87Sr/86Sr) and hydrochemistry monitoring for groundwater hydrodynamics analysis in a karst aquifer (Gran Sasso,Central Italy)

This paper deals with chemical and isotope analyses of 21 springs, which were monitored 3 times in the course of 2001; the monitoring program was focused on the groundwater of the Gran Sasso carbonate karst aquifer (Central Italy), typical of the mountainous Mediterranean area.Based on the hydrogeological setting of the study area, 6 groups of springs with different groundwater circulation patterns were distinguished. The hydrogeochemistry of their main components provided additional information about groundwater flowpaths, confirming the proposed classification. The spatial distribution of their ion concentrations validated the assumptions underlying the hydrogeological conceptual model, showing diverging groundwater flowpaths from the core to the boundaries of the aquifer. Geochemical modelling and saturation index computation elucidated water–carbonate rock interaction, contribution by alluvial aquifers at the karst aquifer boundaries, as well as impacts of human activities.The analysis of ¹⁸O/¹⁶O and ²H/H values and their spatial distribution in the aquifer substantiated the hydrogeology-based classification of 6 groups of springs, making it possible to trace back groundwater recharge areas based on mean isotope elevations; the latter were calculated by using two rain monitoring stations. ⁸⁷Sr/⁸⁶Sr analyses showed seasonal changes in many springs: in winter–spring, the changes are due to inflow of new recharge water, infiltrating into younger rocks and thus increasing ⁸⁷Sr/⁸⁶Sr values; in summer–autumn, when there is no recharge and spring discharge declines, changes are due to base flow groundwater circulating in more ancient rocks, with a subsequent drop in ⁸⁷Sr/⁸⁶Sr values.The results of this study stress the contribution that spatio-temporal isotope monitoring can give to the definition of groundwater flowpaths and hydrodynamics in fissured and karst aquifers, taking into account their hydrogeological and hydrogeochemical setting.     

Tracer tests, hydrochemical and microbiological investigations as a basis for groundwater protection in a remote tropical mountainous karst area, Vietnam

The Tam Duong karst area in NW Vietnam is among the poorest and remotest regions in the country. The local population largely depends on water from two main karst springs. Due to agricultural activity and untreated domestic wastewaters, the spring water is often microbiologically contaminated. In order to provide a scientific basis for groundwater protection in the area, different field methods have been applied including hydrogeological framework investigations, tracer tests, and hydrochemical and microbiological sampling and analyses. All methods had to be adapted to the conditions of a poor and remote area. These adaptations included, amongst other measures, the use of a portable microbiological water_testing kit and the involvement of the local population in the sampling campaign. The tracer tests showed simple and direct connections between two important swallow holes and the two main springs, and made it possible to determine the linear groundwater flow velocities, which are extremely high (up to 875 m/h). The hydrochemical and microbiological data confirmed the strong impact of the streams sinking into the swallow holes on the spring water quality. Future groundwater source protection strategies should consequently focus on the reduction of polluting activities near the sinking streams and within their catchment areas.     

Determination of the origin of the Helvadere drinking springs by means of hydrochemical and isotopic techniques, Aksaray, Central Anatolia, Turkey

The main aquifer of the Helvadere springs that emerges on the strike-slip of the Hasanda?? fault set alongside the Tuzgölü (salt lake) fault zone, and trends in a NW–SE direction of Aksaray city, in the western part of Central Anatolia, is the exposed rocks of Hasanda?? which are volcanics that have distinct hydrogeological properties. The meteoric origin of the spring waters is deduced from hydrochemical and environmental isotope (¹⁸O, ²H, ³H) studies. The springs have high discharge (Q>100?l/s) and low ion concentrations because of fast circulation along the groundwater flow path in the aquifer. Furthermore, because it has Ca-Na-Mg-HCO₃ hydrochemical facies, it conforms to high standards of drinking and irrigation water.     

Hydrogeological characteristics of some deep siphonal springs in Serbia and Montenegro karst

In terms of hydrogeological, engineering-geological, and hydrotechnical tapping in karst in relation to ground waters, karst channels, springs and ponors, speleodiving is the only research method which enables direct observation, studying and exact geological mapping of karst channels and caverns. Data collected during speleodiving research contribute considerably to the analysis of karst evolution process in the given region, which is very important in evaluating the depth of karstification and determining the main direction of the groundwater flow. In the past 30 years in Serbia and Montenegro, speleodivers have investigated over 40 siphonal springs, active cave channels and ponors, of which more than 20 are proof of deep siphonal circulation in karstic aquifers. The karstic springs are the most interesting phenomenon from a hydrogeological view point, and their investigations need particular attention. Most of significant karstic springs are on the rims of erosion basins—perimeters of karst poljes, river valleys, sea coasts and contact areas between karst aquifers and hydrogeological barriers. General characteristics of the spring regime are the direct correlation between precipitation and spring discharge. Moreover, the hydrogeological regime of these springs also depends on the size of the catchment area, karstic aquifer retardation capacity, total porosity, as well as lithological and structural characteristics.     

Hydrogeological and hydrochemical features of an area polluted by heavy metals in central Nicaragua

Geophysical and hydrochemical surveys were used to investigate the hydrogeological conditions in one of the Río Sucio microbasins, in central Nicaragua. Zones of vertical structures (i.e. fractures and quartz veins) and weathering were mapped using Continuous Vertical Electrical Soundings (CVES), as such zones are of major importance for groundwater transport. Water from the springs was analysed to determine concentrations of major ions and heavy metals. Low ion concentrations and ¹⁸O analyses indicate that the springs occur close to their recharge areas and there is a relatively rapid groundwater circulation. Mercury (Hg) content in the springs was low, while comparatively high amounts of lead (Pb) were found. The results presented here demonstrate the important function of weathering and tectonics in the occurrence of groundwater systems in the basin. Hg and Pb found in the springs’ water reveal the existence of an increase in pollution sources disseminating in the area. More than 100 years of using mercury in the gold-mining industry and releasing wastes into rivers has affected water quality and ecosystems. Further investigations are needed in this area to determine the groundwater vulnerability to this pollution as this resource may be needed in the future.The online version of the original article can be found at     

Identifying sources of salinization using hydrochemical and isotopic techniques, Konarsiah, Iran

Konarsiah salt diapir is situated in the Simply Folded Zone of the Zagros Mountain, south Iran. Eight small permanent brine springs emerge from the Konarsiah salt body, with average total dissolved solids of 326.7 g/L. There are numerous brackish to saline springs emerging from the alluvial and karst aquifers adjacent to the diapir. Concerning emergence of Konarsiah diapir in the study area, halite dissolution is the most probable source of salinity in the adjacent aquifers. However, other sources including evaporation and deep brines through deep Mangerak Fault are possible. The water samples of the study area were classified based on their water-type, salinity, and the trend of the ions concentration curves. The result of this classification is in agreement with the hydrogeological setting of the study area. The hydrochemical and isotopic evaluations show that the groundwater samples are the result of mixing of four end members; Gachsaran sulfate water, Sarvak and Asmari carbonate fresh waters, and diapir brine. The molar ratios of Na/Cl, Li/Cl, Br/Cl, and SO₄/Cl; and isotopic signature of the mixed samples justify a groundwater mixing model for the aquifers adjacent to the salt diapir. The share of brine in each adjacent aquifer was calculated using Cl mass balance. In addition, concentrations of 34 trace elements were determined to characterize the diapir brine and to identify the possible tracers of salinity sources in the mixed water samples. B, Mn, Rb, Sr, Cs, Tl, and Te were identified as trace elements evidencing contact of groundwater with the salt diapir.     

Hydro-morphological characteristics and hydrogeological functioning of a wetland system: a case study in southern Spain

The analysis and interpretation of physical and limnological parameters combined with hydrochemical (major ions and stable isotopes) analyses enabled us to evaluate the hydrogeological functioning and the hydrogeochemical evolution of groundwater in two adjacent lakes related to a karstic aquifer (Archidona, southern Spain). Lake water, groundwater and the outflow from a spring, were monitored periodically from 1998 to 1999 and sporadically from 2000 to 2006. The evolution of groundwater chemistry from recharge (dolines) to discharge areas (spring) showed an increment of 20% in magnesium and 15% in sulphate, and such higher increments were recorded for the water from the lakes, suggesting the existence of different hydrogeological paths. A simple water budget model, together with morphological interpretation, suggests that groundwater discharge into the lakes is of relative importance to the input into these systems. Finally, we believe that the development of a new typology for hydro-morphological elements, by means of several hydrological factors and the assessment of pressures and impacts will be useful for the correct management of these lakes and other semi-arid aquatic ecosystems.     

Factors which determine the hydrogeochemical behaviour of karstic springs. A case study from the Betic Cordilleras,Spain

The Cabra-Alcaide karstic massif situated in the south of Spain constitutes an important part of the so-called Natural Park of the Subbetic Sierras. This aquifer system is drained by various springs which supply a population of some 100,000 inhabitants. The feed areas of these springs show very different characteristics with respect to their geological structure, size of the drainage area, thickness of the vadose zone, elevation and degree of karstification. In addition, the carbonate rocks lie over a clayey substratum which contains large masses of intercalated evaporites. Due to these conditions, the hydrochemical composition of the springs is relatively variable. In this study a hydrogeochemical characterization of the aquifer in both space and time is undertaken and the factors that determine it are discussed. To achieve this, 19 monthly samples were taken from the 6 most significant springs of the hydrogeological system. The commencement of sampling coincided with the transition from a period of several years of severe drought and a very wet two-year period, which amplified considerably the hydrochemical and hydrodynamic response of the springs to the recharge. Identification of hydrogeochemical processes was performed by studying hydrographs, the temporal evolution of physico-chemical parameters, ionic ratios (mainly Mg/Ca) and by means of simple and multivariate statistical analyses. The saturation status was established using the WATEQF program and the mass transfer was quantified using PHREEQC. With the exception of the epikarstic subsystem (i.e. the Zarza spring), the majority of the results indicate that the aquifer exhibits a diffuse flow model, in which piston flow phenomena are seen, closely linked to the most intense precipitation. Along the direction of flow hydrochemical trends are seen as the water type changes from Ca–HCO₃ to Ca–Mg–HCO₃; at the same time enrichment in some ions, derived from the dissolution of evaporitic minerals of the impermeable substratum, and dedolomitization processes occur. In this way, almost 90% of the water samples were oversaturated in calcite, the majority of cases being a consequence of the dissolution of the gypsum of the substratum. Only in the epikarstic springs can it be considered that the oversaturation in calcite is due to loss of CO₂ from the emerging groundwater. It is concluded that hydrodynamic aspects together with hydrogeochemical characteristics need to be taken into account to correctly explain the hydrochemical evolution of the karstic springs. Moreover, the use of both approaches permits a more accurate establishment of the degree of aquifer karstification, which in turn needs to be known in order to assess its vulnerability to contamination and to protect recharge zones.