Special Issue "Inland and Coastal Karst Aquifers: Functioning, Monitoring and Management"

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Hydrogeology".

Deadline for manuscript submissions: closed (31 July 2018)

Special Issue Editors

Guest Editor
Prof. M. Dolores Fidelibus

Polytechnic University of Bari, 70126 Bari BA, Italy
Website | E-Mail
Interests: hydrogeology; karst; hard rocks; karst geomorphology; coastal aquifers; natural tracers; mass transport; contaminated sites; ground water monitoring; submarine springs
Guest Editor
Prof. Antonio Pulido Bosch

University of Almeria, 04120 Almeria, Spain
Website | E-Mail
Interests: hydrogeology; karst; karst geomorphology; coastal aquifers; boron hydrogeochemistry; monitoring and management of karst aquifers; artificial recharge

Special Issue Information

Dear Colleagues,

The special issue is addressed to either inland or coastal karst aquifers. They are both complex systems, but in the coastal ones the complexity of the variable-density flow joins to the complexity of the intrinsic features of the karst medium. In the karst aquifers located in areas with a climate that favours the human life the pressure exerted by an increasing demography and related activities (particularly the agriculture) involves a high (and growing) water-demand, which has frequently scarce chances to be satisfied due to the low natural availability conditions. Thus, water resources are subject to a perennial hydrological stress, along with pollution and, in coastal aquifers, also seawater intrusion/salinization. Compared to other aquifers, fresh waters of karst aquifers are of excellent quality for drinking purposes, thus deserving high attention: in many regions they represent the unique source not only for supporting the potable sector, but also the ecosystem services and the human activities.

The intrinsic features of karst aquifers and, for the coastal ones, the peculiar border conditions, make surely difficult to define their functioning and their vulnerability (which for coastal aquifers, is a 3D vulnerability), the rules for their management, as well as the future of water resources ensuing the climate change (and sea level rise).

The issue welcomes new insights and research innovations on both inland and coastal karst aquifers.

Tentative topics, however partial, are: measuring, monitoring and modelling approaches; role of faults; fractures and karst forms in pollutant transport and/or salinization; intrinsic vulnerability and vulnerability to salinization; relation of karst ground waters with groundwater dependent ecosystems; chemical processes at the land-sea interface and submarine groundwater discharge (its assessment and effects on the marine environment); chemical processes in the mixing zone in relation to tides and sea level change; direct, proxy or remote control of seawater intrusion/salinization; genesis and exploitation of submarine springs; management approaches involving technical and social dimensions.

Prof. M. Dolores Fidelibus
Prof. Antonio Pulido Bosch
Guest Editors

Manuscript Submission Information

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Keywords

  • Karst aquifer
  • Karst coastal aquifer
  • Seawater intrusion
  • Anisotropy
  • SGWD
  • Groundwater dependent ecosystems (GDE)
  • Monitoring
  • Modelling
  • Groundwater management

Published Papers (10 papers)

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Research

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Open AccessArticle Cross-Correlation and Cross-Spectral Analysis of the Hydrographs in the Northern Part of the Dinaric Karst of Croatia
Geosciences 2019, 9(2), 86; https://doi.org/10.3390/geosciences9020086
Received: 24 December 2018 / Revised: 31 January 2019 / Accepted: 31 January 2019 / Published: 13 February 2019
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Abstract
Correlation and cross-spectral analysis of hydrographs was performed on the karst area of the mountainous section of the Kupa River in two time periods. Since there are karst aquifers in this area that is a part of strategic groundwater reserves of potable water, [...] Read more.
Correlation and cross-spectral analysis of hydrographs was performed on the karst area of the mountainous section of the Kupa River in two time periods. Since there are karst aquifers in this area that is a part of strategic groundwater reserves of potable water, such an analysis could give better insight into the behavior of these aquifers. The functions used to describe karst aquifers are the cross-correlation function, coherence function, gain function, and phase function. The outcomes of the analysis results were very similar in the two analyzed periods, suggesting that differences in input signals between these two periods do not affect the aquifer function as a system filter. The results of this research suggest that the aquifer and overburden layer characteristics have a much stronger influence than the change of input signal on the runoff regime in the considered period. Full article
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Open AccessArticle Groundwater Temperature as an Indicator of the Vulnerability of Karst Coastal Aquifers
Geosciences 2019, 9(1), 23; https://doi.org/10.3390/geosciences9010023
Received: 11 December 2018 / Revised: 21 December 2018 / Accepted: 24 December 2018 / Published: 30 December 2018
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Abstract
Coastal karst aquifers show a three-dimensional vulnerability, which consists of the whole of the “intrinsic vulnerability” and the “groundwater vulnerability to seawater intrusion”. The results of a study carried out in the Salento karst coastal aquifer (southern Italy) show that temperature, as well [...] Read more.
Coastal karst aquifers show a three-dimensional vulnerability, which consists of the whole of the “intrinsic vulnerability” and the “groundwater vulnerability to seawater intrusion”. The results of a study carried out in the Salento karst coastal aquifer (southern Italy) show that temperature, as well as being a reliable tracer of groundwater flow, is also an effective indicator of vulnerability in anisotropic media. The trend of isotherms related to a cross-section of the aquifer thermal field, combined with geological, geomorphological, and hydrogeological information, allows the role of faults and dolines in the mass transport from ground surface to be inferred. Isotherm trends may also give information on the permeability distribution along faults. A specific temperature value evidence the saltwater top, thus indicating the groundwater vulnerability to salinization. Full article
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Open AccessArticle Enhanced Characterization of the Krania–Elassona Structure and Functioning Allogenic Karst Aquifer in Central Greece
Geosciences 2019, 9(1), 15; https://doi.org/10.3390/geosciences9010015
Received: 12 November 2018 / Revised: 16 December 2018 / Accepted: 17 December 2018 / Published: 27 December 2018
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Abstract
The present study highlights the importance of geological, hydrogeological, and hydrogeochemical characterization of a karst aquifer in building a conceptual model of the system. The karst system of Krania–Elassona in central Greece was chosen for this application. Hydrogeological research included geological mapping and [...] Read more.
The present study highlights the importance of geological, hydrogeological, and hydrogeochemical characterization of a karst aquifer in building a conceptual model of the system. The karst system of Krania–Elassona in central Greece was chosen for this application. Hydrogeological research included geological mapping and hydrogeological analysis. Additionally, hydrochemical analysis of water samples was performed in boreholes, rivers, and the system’s main spring. The Krania–Elassona aquifer consists of three horizons of marbles and is characterized by mature karstification. The karst aquifer is characterized by allogenic recharge mainly from the River Deskatis that accounts for up to 92% of the total flow. Groundwater and spring water are generally characterized as good quality and are suitable for irrigation and domestic use. The water type of the spring water is classified as Mg-HCO3. The application of a SARIMA (Seasonal Autoregressive Integrated Moving Average Model) model verified the conceptual model and successfully simulated spring discharge for a two-year period. The results of this study highlight the importance of basic hydrogeological research and the initial conceptualization of karst systems in reliably assessing groundwater vulnerability and modeling. Full article
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Open AccessArticle Hellenic Karst Aquifers Vulnerability Approach Using Factor Analysis: The Example of the Louros Karst Aquifers
Geosciences 2018, 8(11), 417; https://doi.org/10.3390/geosciences8110417
Received: 23 July 2018 / Revised: 30 October 2018 / Accepted: 5 November 2018 / Published: 13 November 2018
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Abstract
The karst aquifers of the Hellenic territory display high vulnerability that is related to the existence of the epikarst zone. If present, the epikarst zone regulates the vertical movement of the groundwater, which results in the chemical pollutants staying longer within it, thus [...] Read more.
The karst aquifers of the Hellenic territory display high vulnerability that is related to the existence of the epikarst zone. If present, the epikarst zone regulates the vertical movement of the groundwater, which results in the chemical pollutants staying longer within it, thus facilitating the inactivation of the microbial loads. The Hellenic karst is well developed; it displays high hydraulic conductivity, relatively large storage, and the characteristics of an important water reservoir. Although its porosity was calculated to be between 0.005–8%, the statistical processing of the springs’ discharge time series points to an increased storage. The increased storage was attributed to the presence of the epikarst zone, which regulates the water movement to the underlying formations, and finally to its discharge from the karst system through springs. In these areas, the influence of nitrogen compounds on the water quality is evident. The presence of cyanobacteria and toxic substances at concentrations that are too high for fresh, flowing waters whose temperature does not exceed 17 °C advocates the role of nutrients, even at concentrations that do not exceed the maximum permissible limits of drinking water. In mountainous areas, where agriculture is limited, the presence of these compounds is attributed to heavily polluting land uses. The impact of such uses became apparent from the application of factor analysis, which not only highlighted their contribution to the overall groundwater quality, but also determined their geographical distribution and origin. From the above, it becomes evident that there is a need for protection of the karst aquifers, and investigation of their vulnerability mechanisms. The Hellenic karst, which is expected to cover the drinking water needs in the near future, proves to be very vulnerable to any kind of pollution. Full article
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Open AccessArticle Identifying Karst Aquifer Recharge Areas using Environmental Isotopes: A Case Study in Central Italy
Geosciences 2018, 8(9), 351; https://doi.org/10.3390/geosciences8090351
Received: 27 July 2018 / Revised: 22 August 2018 / Accepted: 13 September 2018 / Published: 15 September 2018
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Abstract
Water resources management is one of the most important challenges worldwide because water represents a vital resource for sustaining life and the environment. With the aim of sustainable groundwater management, the identification of aquifer recharge areas is a useful tool for water resources [...] Read more.
Water resources management is one of the most important challenges worldwide because water represents a vital resource for sustaining life and the environment. With the aim of sustainable groundwater management, the identification of aquifer recharge areas is a useful tool for water resources protection. In a well-developed karst aquifer, environmental isotopes provide support for identifying aquifer recharge areas, residence time and interconnections between aquifer systems. This study deals with the use of environmental isotopes to identify the main recharge area of a karst aquifer in the Upper Valley of Aniene River (Central Italy). The analysis of 18O/16O and 2H/H values and their spatial distribution make it possible to trace back groundwater recharge areas based on average isotope elevations. The Inverse Hydrogeological Balance Method was used to validate spring recharge elevations obtained by the use of stable isotopes. Areas impacted by direct and rapid rainfall recharge into the study area were delineated, showing groundwater flowpaths from the boundaries to the core of the aquifer. The results of this study demonstrate the contribution that spatial and temporal isotope changes can provide to the identification of groundwater flowpaths in a karst basin, taking into account the hydrogeological setting. Full article
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Open AccessArticle Assessment of Specific Yield in Karstified Fractured Rock through the Water-Budget Method
Geosciences 2018, 8(9), 344; https://doi.org/10.3390/geosciences8090344
Received: 26 July 2018 / Revised: 1 September 2018 / Accepted: 1 September 2018 / Published: 11 September 2018
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Abstract
In this note, the Water Budget Method (WBM) is applied to estimate local values of the specific yield of the deep karst aquifer of Salento peninsula. A selection in a period of two years of relevant short precipitation events has been considered and [...] Read more.
In this note, the Water Budget Method (WBM) is applied to estimate local values of the specific yield of the deep karst aquifer of Salento peninsula. A selection in a period of two years of relevant short precipitation events has been considered and the related localized recharges have been compared to the water table fluctuations measured at two selected wells. The recharge amounts have been corrected by using data of evapotranspiration and soil water storage available from a micrometeorological base. The results are very similar for both the wells and more consistent when the corrections are applied. A discussion involving frequency and apertures of the fractures in the rock mass of the aquifer suggests the effect of the karst dissolution to be dominant in determining these values of the specific yield. Full article
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Open AccessArticle Groundwater Characterization by Means of Conservative (δ18O and δ2H) and Non-Conservative (87Sr/86Sr) Isotopic Values: The Classical Karst Region Aquifer Case (Italy–Slovenia)
Geosciences 2018, 8(9), 321; https://doi.org/10.3390/geosciences8090321
Received: 31 July 2018 / Revised: 18 August 2018 / Accepted: 21 August 2018 / Published: 28 August 2018
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Abstract
The study of the different hydrogeological compartments is a prerequisite for understanding and monitoring different fluxes, thereby evaluating the environmental changes in an ecosystem where anthropogenic disturbances are present in order to preserve the most vulnerable groundwaters from contamination and degradation. In many [...] Read more.
The study of the different hydrogeological compartments is a prerequisite for understanding and monitoring different fluxes, thereby evaluating the environmental changes in an ecosystem where anthropogenic disturbances are present in order to preserve the most vulnerable groundwaters from contamination and degradation. In many karst domains in the Mediterranean, areas groundwaters and surface waters are a single system, as a result of the features that facilitate the ingression of waters from surface to subsurface. This is also the case for the Classical Karst hydrostructure, which is a carbonate plateau that rises above the northern Adriatic Sea, shared between Italy and Slovenia. The main suppliers to the aquifer are the effective precipitations and the waters from three different rivers: Reka/Timavo, Soča/Isonzo and Vipava/Vipacco. Past and ongoing hydrogeological studies on the area have focused on the connections within the Classical Karst Region aquifer system through the analysis of water caves and springs hydrographs and chemographs. In this paper, the authors present new combined data from major ions, oxygen, hydrogen and strontium stable and radiogenic isotopes which have allowed a more complementary knowledge of the groundwater circulation, provenance and water-rock interactions. All the actions occurred in the framework of the European project HYDROKARST. Full article
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Open AccessArticle Diffuse Versus Conduit Flow in Coastal Karst Aquifers: The Consequences of Island Area and Perimeter Relationships
Geosciences 2018, 8(7), 268; https://doi.org/10.3390/geosciences8070268
Received: 29 June 2018 / Revised: 15 July 2018 / Accepted: 17 July 2018 / Published: 20 July 2018
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Abstract
The majority of limestone islands are made of eogenetic carbonate rock, with intrinsic high porosity and permeability. The freshwater lenses of small islands are dominated by diffuse flow regimes as the island perimeter is everywhere close to the meteoric catchment of the island [...] Read more.
The majority of limestone islands are made of eogenetic carbonate rock, with intrinsic high porosity and permeability. The freshwater lenses of small islands are dominated by diffuse flow regimes as the island perimeter is everywhere close to the meteoric catchment of the island interior. This flow regime produces flank margin caves at the lens margin, where dissolution is enhanced by mixing corrosion, superposition of organic decay horizons and higher flow velocities as the lens thins. The lens interior develops touching-vug flow systems that result in enhanced permeability and lens thinning over time. As islands become larger, the area (meteoric catchment) goes up by the square, but the island perimeter (discharge zone) goes up linearly; diffuse flow becomes inefficient; conduit flow develops to produce traditional epigenic cave systems that discharge the freshwater lens by specific turbulent flow routes, which in turn are fed by diffuse flow in the island interior. Locally, diffuse flow to the island perimeter continues in coastal proximal areas between major conduit flow routes to produce flank margin caves. The Bahamian Archipelago represents a case history in which tectonics is limited, the rocks are entirely eogenetic and the diffuse to conduit flow transition is demonstrated. Full article
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Open AccessArticle Geophysical Input to Improve the Conceptual Model of the Hydrogeological Framework of a Coastal Karstic Aquifer: Uley South Basin, South Australia
Geosciences 2018, 8(7), 226; https://doi.org/10.3390/geosciences8070226
Received: 17 May 2018 / Revised: 19 June 2018 / Accepted: 19 June 2018 / Published: 21 June 2018
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Abstract
A lack of closely spaced datasets on layer elevations, aquifer parameters, identification of areas with high recharge potential, dominant conduit porosity zones, and well defined boundary conditions hampers the ability of groundwater models to produce a reliable water balance. Typically, geological structure, aquifer [...] Read more.
A lack of closely spaced datasets on layer elevations, aquifer parameters, identification of areas with high recharge potential, dominant conduit porosity zones, and well defined boundary conditions hampers the ability of groundwater models to produce a reliable water balance. Typically, geological structure, aquifer properties, and groundwater heads are obtained from point measurements which are sparse. The drillhole information in aquifers is usually available at locations far apart, distances ranging from hundreds to thousands of meters. Furthermore, pump tests are usually conducted at limited locations and generalized to the aquifer. This limited knowledge leads to errors in the conceptual understanding of the aquifer. In this study, Airborne Electromagnetic Survey (AEM) was used to define base elevations of the aquifers where drillhole information was lacking. Surface Nuclear Magnetic Resonance (sNMR), borehole NMR, Transient Electromagnetic (TEM), and downhole geophysical surveys have given new insight to the conceptualization of hydrogeological framework. These methods are relatively low in cost compared to traditional well drilling and provide information on layer elevations, aquifer parameters, point and diffuse recharge zones, and conduit porosity zones in the profile, which improves our definition of the boundary conditions. From a practical point of view, combining drillhole information with a variety of geophysical techniques provides sound datasets to develop a comprehensive conceptual model. This in turn can be used to build a robust groundwater model. Full article
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Review

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Open AccessReview Coastal Karst Groundwater in the Mediterranean: A Resource to Be Preferably Exploited Onshore, Not from Karst Submarine Springs
Geosciences 2018, 8(7), 258; https://doi.org/10.3390/geosciences8070258
Received: 21 May 2018 / Revised: 3 July 2018 / Accepted: 4 July 2018 / Published: 11 July 2018
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Abstract
Coastal karst aquifers are common in the Mediterranean basin. With their significant potential storage capacity, they are an attractive groundwater resource in areas where the water demand is the most important. They discharge either at the coastal zone or directly into the sea [...] Read more.
Coastal karst aquifers are common in the Mediterranean basin. With their significant potential storage capacity, they are an attractive groundwater resource in areas where the water demand is the most important. They discharge either at the coastal zone or directly into the sea at karst submarine springs (KSMS). Decision makers take an interest in this unconventional groundwater resource and are convinced by companies and research consultancies that KSMS’s should be exploited because they would discharge huge amount of fresh water. Being now well documented, the occurrence of KSMS’s along the Mediterranean coast is discussed in the light of recent geological history favourable to the development of karst. Conduit flow conditions are common, inherited from an intense phase of karstification during the Messinian Crisis of Salinity at the end of Miocene, when the sea level was 1500 to 2500 m below present sea level. From investigations carried out along the coasts of France and the Levant, compared with studies done along other Mediterranean coastlines, it appears that capturing groundwater discharged at KSMS raises different problems which make the operation dicey and expansive. Full article
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