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Special Issue “Focus on the Salinization Issue in the Mediterranean Area”

March 2021
Water 13(5):681

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Università degli Studi della Campania "Luigi Vanvitelli

Throughout the Mediterranean Region, recent and past studies have highlighted an increase in temperature, especially during summer, a decrease in precipitation and a change in the in-year precipitation pattern [...]

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water

Editorial

Special Issue “Focus on the Salinization Issue in the

Mediterranean Area”

Micòl Mastrocicco





Citation: Mastrocicco, M. Special

Issue “Focus on the Salinization Issue

in the Mediterranean Area”. Water

2021,13, 681. https://doi.org/

10.3390/w13050681

Received: 1 March 2021

Accepted: 2 March 2021

Published: 3 March 2021

Publisher’s Note: MDPI stays neutral

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4.0/).

Department of Environmental Biological and Pharmaceutical Sciences and Technologies, University of Campania

“Luigi Vanvitelli”, Via Vivaldi, 43, 81100 Caserta, Italy; micol.mastrocicco@unicampania.it; Tel.: +39-0823-274609

1. Introduction

Throughout the Mediterranean Region, recent and past studies have highlighted an

increase in temperature, especially during summer, a decrease in precipitation and a change

in the in-year precipitation pattern [

–

]. The Mediterranean Region is undergoing inten-

sive demographic, social, cultural, economic and environmental changes. The population

of Mediterranean countries doubled from 240 M in 1960 to 480 M in 2010, with the urban

population of EU Med countries increasing from 57% to 76% in the same period [

]. Most

urbanization takes place along the coastal zones, contributing to increasing the salinization

of water resources. Thus, in the following years with the progressive loss of surface water

resources, groundwater resources will be gradually more stressed, especially in coastal

Mediterranean areas. This makes the Mediterranean a good benchmark to test and validate

scientiﬁc approaches to characterize and better understand the ongoing salinization trends

of water resources. Unfortunately, most of the research efforts on historical and projected

changes focus on the aboveground components of the hydrologic cycle [

]. While, for

the sub-surface components of the hydrologic cycle (e.g., recharge, groundwater levels,

aquifer ﬂuxes and groundwater quality), the research efforts are still in their infancy [

Nevertheless, since the Mediterranean is suffering from the progressive loss of surface

water resources [

], studies on groundwater quality and availability will be pivotal to

understand and regulate the changing hydrologic cycle, especially in coastal areas. The

limited knowledge of the ongoing and future effects of climate change on groundwater

resources thus inspired this Special Issue.

2. Contributions

The main goal of this Special Issue of Water is to focus on different methodological

approaches to improve the understanding of salinization mechanisms of both ground-

water and soil water, which may derive from actual seawater intrusion, paleo-seawater

intrusion, an increase in atmospheric temperatures that in turn drives evapoconcentration

and agricultural return ﬂows. From its ﬁrst announcement, and after being thoroughly

peer reviewed, six papers have been accepted for publication [

–

]. To gain an overview

of the ideas collected by this Special Issue, a brief summary of each published paper is

reported below.

This Special Issue of Water provides a valuable contribution to the characterization of

groundwater salinization in the Mediterranean by collecting and presenting current appli-

cations of ﬁeld-based studies using remote sensing, GIS spatial analyses, environmental

tracers, statistical analyses or combined approaches.

For example, a study focusing on statistical analysis of groundwater data to evaluate

the spatial changes of water level and electrical conductivity has been performed in an in-

tensively characterized and studied coastal phreatic aquifer of Emilia-Romagna (Northeast

Italy) for the decade from 2009 to 2018 [

]. The results highlight the existence of saline

groundwater at the bottom of the aquifer in most of the study area, thus stressing that

groundwater quality is not suitable for human consumption and irrigation. The spatial

Water 2021,13, 681. https://doi.org/10.3390/w13050681 https://www.mdpi.com/journal/water

Water 2021,13, 681 2 of 2

analyses of the horizontal distribution of compound-speciﬁc stable and radioactive isotopes

combined with major dissolved ions in the Grombalia coastal aquifer (Tunisia) were pivotal

to unravel the main geochemical processes driving aquifer salinization and groundwater

residence times [

]. In the same line of research, major and compound-speciﬁc isotope

analyses were combined with major ions to disentangle the ongoing salinization and factors

inﬂuencing groundwater quality in the coastal archeological site of Cumae located in the

volcanic district of the Phlegraean Fields (Southern Italy) [

]. Another contribution of this

Special Issue tackles complex transboundary aquifer management affected by different

sources of salinization that threaten the well ﬁeld of the Lower Yarmouk Gorge (LYG)

shared by Israel, Jordan and Syria [

]. In a different line of research, the study presented

by Kasim et al. [

] analyzed the salt-affected land which is predominant in the Keriya

River area of Northwestern China via satellite band reﬂectance and newly optimum spec-

tral indices (OSIs) based on two-dimensional and three-dimensional data. Finally, a review

paper closes this Special Issue discussing the new advances and challenges that still must

be faced in the Mediterranean with a special focus on predictions of climate change effects

on coastal aquifers, which surely deserve additional research [15].

I believe that, with the articles published in this Special Issue, the topic of groundwa-

ter salinization in the Mediterranean will receive more attention by the wider scientiﬁc

community and that the need to deal with groundwater salinization issues will be better

understood and shared.

Funding: This research received no external funding.

Conﬂicts of Interest: The author declares no conﬂict of interest.

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Kasim, N.; Maihemuti, B.; Sawut, R.; Abliz, A.; Dong, C.; Abdumutallip, M. Quantitative Estimation of Soil Salinization in an

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ResearchGate has not been able to resolve any citations for this publication.

Evolution of Salinity and Water Table Level of the Phreatic Coastal Aquifer of the Emilia Romagna Region (Italy)

Article

Full-text available

Jan 2021

The coastal aquifers of the Mediterranean region are highly susceptible to seawater intrusion due to a combination of challenges such as land subsidence, high aquifer permeability, urbanization, drainage, and an unsustainable use of water during the dry summer months. The present study is focused on a statistical analysis of groundwater data to evaluate the spatial changes of water level and electrical conductivity in the coastal phreatic aquifer of the Emilia-Romagna (Northeast Italy) for the period from 2009 to 2018. Data from 35 wells distributed across the entire regional coastal area are used to establish a temporal trend, as well as correlations between salinity, water table level, and rainfall. Water table and salinity distribution maps for the entire study area are discussed regarding surface geology and water management. Most of the wells are in the beach wedge sand unit, which allows for easy connectivity between groundwater and surface water. Surface water and groundwater salinization are enhanced along the surface water bodies connected to the sea. The lowest water table level occurs in the western and northern parts of the study area, because of the semiconfined behavior of the aquifer. Only in the northernmost, close to the Po River, and in the southernmost parts of the study area does the groundwater remain fresh for the whole period considered due to river aquifer recharge. In the rest of the region, the thickness of freshwater lenses, where present, is less than 4.5 m. The existence of a water table level below sea level and high saline water at the bottom of the aquifer in most of the study area suggest that the aquifer is in unstable hydrodynamic conditions and groundwater quality is not fit for human consumption or for irrigation. This study is the first to provide a regional overview of the state of groundwater level and salinization within the coastal aquifer of the Emilia-Romagna Region; it also suggests that, overall, the salinization trend has slightly decreased from 2009 to 2018.

Coastal Aquifer Salinization in Semi-Arid Regions: The Case of Grombalia (Tunisia)

Article

Full-text available

Jan 2021

Groundwater resources are facing increasing pressure especially in semi-arid regions where they often represent the main freshwater resource to sustain human needs. Several aquifers in the Mediterranean basin suffer from salinization and quality degradation. This study provides an assessment of Grombalia coastal aquifer (Tunisia) based on multidisciplinary approach that combines chemical and isotopic (δ2H, δ18O, 3H, 14C and δ13C) methods to characterize the relation between groundwater quality variation and aquifer recharge. The results indicate that total dissolved solids exceed 1000 mg/L in the most of samples excepting the recharge area. In addition to water–rock interaction, evaporation and nitrate pollution contributing to groundwater mineralization, the reverse cation exchange process constitute an important mechanism controlling groundwater mineralization with enhancing risk of saltwater intrusion. Environmental isotope tracers reveal that groundwater is evolving within an open system to close system. A significant component of recent water that is recharging Grombalia aquifer system is confirmed by applying correction models based on the δ13C values and 14C activities and tritium contents. However, this recharge, which is mainly associated to the return flow of irrigation water, contributes to the groundwater salinization, especially for the shallow aquifer.

The Issue of Groundwater Salinization in Coastal Areas of the Mediterranean Region: A Review

Article

Full-text available

Jan 2021

The Mediterranean area is undergoing intensive demographic, social, cultural, economic, and environmental changes. This generates multiple environmental pressures such as increased demand for water resources, generation of pollution related to wastewater discharge, and land consumption. In the Mediterranean area, recent climate change studies forecast large impacts on the hydrologic cycle. Thus, in the next years, surface and ground-water resources will be gradually more stressed, especially in coastal areas. In this review paper, the historical and geographical distribution of peer-review studies and the main mechanisms that promote aquifer salinization in the Mediterranean area are critically discussed, providing the state of the art on topics such as actual saltwater wedge characterization, paleo-salinities in coastal areas, water-rock interactions, geophysical techniques aimed at delineating the areal and vertical extent of saltwater intrusion, management of groundwater overexploitation using numerical models and GIS mapping techniques for aquifer vulnerability to salinization. Each of the above-mentioned approaches has potential advantages and drawbacks; thus, the best tactic to tackle coastal aquifer management is to employ a combination of approaches. Finally, the number of studies focusing on predictions of climate change effects on coastal aquifers are growing but are still very limited and surely need further research.

Natural and Anthropogenic Groundwater Contamination in a Coastal Volcanic‐Sedimentary Aquifer: The Case of the Archaeological Site of Cumae (Phlegraean Fields, Southern Italy)

Article

Full-text available

Dec 2020

Archeological sites close to coastal volcanic‐sedimentary aquifers are threatened by groundwater contaminated by natural and anthropogenic processes. The paper reports on a hydrogeological, chemical (major, minor and trace elements) and isotopic (δD‐H2O, δ18O‐H2O, δ15N‐NO3, δ18O‐NO3, δ11B, 222Rn) survey of groundwater at the Cumae archaeological site, which is located in the coastal north‐western sector of the volcanic district of Phlegraean Fields (southern Italy), where groundwater flooding phenomena occur. Results show the presence of a complex coastal volcanic‐sedimentary aquifer system where groundwater quality is influenced mainly by: (i) aquifer lithology and localized ascent of magmatic fluids along buried volcano‐tectonic discontinuities, (ii) mixing of groundwater, deep mineralized fluids and seawater during groundwater pumping, and (iii) nitrate contamination >50 mg/L from non‐point agricultural sources. Moreover, δD and δ18O point toward fast recharge from seasonal precipitations, while the isotopic ratios of N and O in nitrate reveal the contribution of mineral and organic fertilizers as well as leakage from septic tanks. Results can assist the local archaeological authority for the safeguarding and management of the archaeological heritage of the Cumae site.

Sources of Salinization of Groundwater in the Lower Yarmouk Gorge, East of the River Jordan

Article

Full-text available

May 2020

In the Lower Yarmouk Gorge the chemical composition of regional, fresh to brackish, mostly thermal groundwater reveals a zonation in respect to salinization and geochemical evolution, which is seemingly controlled by the Lower Yarmouk fault (LYF) but does not strictly follow the morphological Yarmouk Gorge. South of LYF, the artesian Mukeihbeh well field region produces in its central segment groundwaters, an almost pure basaltic-rock type with a low contribution (<0.3 vol-%) of Tertiary brine, hosted in deep Cretaceous and Jurassic formations. Further distal, the contribution of limestone water increases, originating from the Ajloun Mountains in the South. North of the LYF, the Mezar wells, the springs of Hammat Gader and Ain Himma produce dominantly limestone water, which contains 0.14–3 vol-% of the Tertiary brine, and hence possesses variable salinity. The total dissolved equivalents, TDE, of solutes gained by water/rock interaction (WRI) and mixing with brine, TDE WRI + brine , amount to 10%–70% of total salinity in the region comprising the Mukheibeh field, Ain Himma and Mezar 3 well; 55%–70% in the springs of Hammat Gader; and 80%–90% in wells Mezar 1 and 2. The type of salinization indicates that the Lower Yarmouk fault seemingly acts as the divide between the Ajloun and the Golan Heights-dominated groundwaters.

Quantitative Estimation of Soil Salinization in an Arid Region of the Keriya Oasis Based on Multidimensional Modeling

Article

Full-text available

Mar 2020

Soil salinity is one of the major factors causing land degradation and desertification on earth, especially its important damage to farming activities and land-use management in arid and semiarid regions. The salt-affected land is predominant in the Keriya River area of Northwestern China. Then, there is an urgent need for rapid, accurate, and economical monitoring in the saltaffected land. In this study, we used the electrical conductivity (EC) of 353 ground-truth measurements and predictive capability parameters of WorldView-2 (WV-2), such as satellite band reflectance and newly optimum spectral indices (OSI) based on two dimensional and threedimensional data. The features of spectral bands were extracted and tested, and different new OSI and soil salinity indices using reflectance of wavebands were built, in which spectral data was preprocessed (based on First Derivative (R-FD), Second Derivative (R-SD), Square data (R-SQ), Reciprocal inverse (1/R), and Reciprocal First Derivative (1/R-FD)), utilizing the partial least-squares regression (PLSR) method to construct estimation models and mapping the regional soil-affected land. The results of this study are the following: (a) the new OSI had a higher relevance to EC than one-dimensional data, and (b) the cross-validation of established PLSR models indicated that the β-PLSR model based on the optimal three-band index with different process algorithm performed the best result with R2V = 0.79, Root Mean Square Errors (RMSEV) = 1.51 dS·m−1, and Relative Percent Deviation (RPD) = 2.01 and was used to map the soil salinity over the study site. The results of the study will be helpful for the study of salt-affected land monitoring and evaluation in similar environmental conditions.

Deciphering Interannual Temperature Variations in Springs of the Campania Region (Italy)

Article

Full-text available

Feb 2019

While the effects of climate change on the thermal regimes of surface waters have already been assessed by many studies, there is still a lack of knowledge on the effects on groundwater temperature and on the effects on spring water quality. The online available dataset of the Campania Environmental Agency (ARPAC) was analysed via spatial, temporal and statistical analyses to assess the impact of climate variability on 118 springs, monitored over the period from 2002 to 2017. The meteorological dataset was used to compute average annual precipitation and atmospheric temperatures. Spring water temperatures, electrical conductivity, pH, chloride and fluoride were selected to determine if climate variations had a significant impact on spring water quality. This study shows that the Campania region has experienced an increase of spring water temperatures of approximately 2.0 °C during the monitored period. This is well-linked with the increase of atmospheric minimum temperatures, but not with average and maximum atmospheric temperatures. The spring water temperature increases were not reflected by a concomitant change of the analysedwater quality parameters. The latter were linked to the precipitation trend and other local factors, like spring altitude and the presence of geothermal heat fluxes.

Ground water and climate change

Article

Full-text available

Apr 2013

As the world's largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate change as more frequent and intense climate extremes (droughts and floods) increase variability in precipitation, soil moisture and surface water. Here we critically review recent research assessing the impacts of climate on ground water through natural and human-induced processes as well as through groundwater-driven feedbacks on the climate system. Furthermore, we examine the possible opportunities and challenges of using and sustaining groundwater resources in climate adaptation strategies, and highlight the lack of groundwater observations, which, at present, limits our understanding of the dynamic relationship between ground water and climate.

Climate change and water in the UK: Recent scientific evidence for past and future change

Article

Jan 2017
PROG PHYS GEOG

A changing climate is anticipated to alter hydroclimatological and hydroecological processes across the UK and around the world. This paper builds on a series of reports commissioned in 2012 (Water Climate Change Impacts Report Card [WCCRC], 2012) and published in a special issue of Progress in Physical Geography in 2015 that interpreted and synthesised the relevant, peer-reviewed scientific literature of climate change impacts on the UK’s water environment. It aims to provide reliable, clear information about the potential impacts of climate change on hydrology and the water environment. We review new evidence since 2012 for historical and potential future changes in precipitation and evapotranspiration, river flows and groundwater levels, river and groundwater temperature/quality and, finally, aquatic ecosystems. Some new evidence exists for change in most of these hydrological components, typically in support of the spatial and temporal trends reported in WCCRC 2012. However, it remains the case that more research has been conducted on rainfall and river flows than evapotranspiration, groundwater levels, river and groundwater temperature, water quality or freshwater ecosystems. Consequently, there remains a clear disparity of robust evidence for historical and potential future change between the top and bottom of the hydroclimatological–hydroecological process chain. As was the case in WCCRC 2012, this remains a significant barrier to informed climate change adaptation in these components of the water environment.

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