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Author |
Siarkos, I.; Latinopoulos, P. |
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Title |
Modeling seawater intrusion in overexploited aquifers in the absence of sufficient data: application to the aquifer of Nea Moudania, northern Greece |
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Journal Article |
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Year  |
2016 |
Publication |
Hydrogeology Journal |
Abbreviated Journal |
Hydrogeology J. |
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Volume |
24 |
Issue |
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Pages |
2123–2141 |
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Keywords |
Groundwater flow, Seawater intrusion, Numerical modeling, Greece, Sensitivity analysis |
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Abstract |
In many coastal areas, overexploitation of groundwater resources has led both to the quantitative degradation of local aquifers and the deterioration of groundwater quality due to seawater intrusion. To investigate the behavior of coastal aquifers under these conditions, numerical modeling is usually implemented; however, the proper implementation of numerical models requires a large amount of data, which are often not available due to the time-consuming and costly process of obtaining them. In the present study, the investigation of the behavior of coastal aquifers under the lack of adequate data is
attempted by developing a methodological framework consisting of a series of numerical simulations: a steady-state, a false-transient and a transient simulation. The sequence and the connection between these simulations constitute the backbone of the whole procedure aimed at adjusting the various
model parameters, as well as obtaining the initial conditions for the transient simulation. The validity of the proposed methodology is tested through evaluation of the model calibration procedure and the estimation of the simulation errors (mean error, mean absolute error, root mean square error, mean relative error) using the case of Nea Moudania basin, northern Greece. Furthermore, a sensitivity analysis is performed in order to minimize the error estimates and thus to maximize the reliability of the models. The results of the whole procedure affirm the proper implementation of the developed methodology under specific conditions and assumptions due to the lack of sufficient data, while they give a clear picture of the aquifer’s quantitative and qualitative status. |
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Address |
Ilias Siarkos: isiarkos@civil.auth.gr; Pericles Latinopoulos latin@civil.auth.gr |
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Corporate Author |
School of Civil Engineering, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece |
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IAH |
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Springer |
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English |
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ISSN |
1431-2174 |
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Area |
Hydrogeology; groundwater modelling, sea water intrusion |
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Approved |
yes |
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Call Number |
MGRE @ redha.menani @ |
Serial |
52 |
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Author |
Petelet-Giraud, E.; Négrel, P.; Aunay, B.; Ladouche, B.; Bailly-Comte, V.; Guerrot, C.; Flehoc, C.; Pezard, P.; Lofi, J.; Dörfliger, N. |
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Title |
Coastal groundwater salinization: Focus on the vertical variability in a multi-layered aquifer through a multi-isotope fingerprinting (Roussillon Basin, France) |
Type |
Journal Article |
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Year |
2016 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
566-567 |
Issue |
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Pages |
398-415 |
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Keywords |
Groundwater salinization, Coastal aquifer, Roussillon Basin, Isotopes, Westbay System, Barcarès and Canet sites |
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Abstract |
The Roussillon sedimentary Basin (South France) is a complex multi-layered aquifer, close to the Mediterranean Sea facing seasonally increases of water abstraction and salinization issues. We report geochemical and isotopic vertical variability in this aquifer using groundwater sampled with a Westbay System® at two coastal monitoring sites: Barcarès and Canet. The Westbay sampling allows pointing out and explaining the variation of water quality along vertical profiles, both in productive layers and in the less permeable ones where most of the chemical processes are susceptible to take place. The aquifer layers are not equally impacted by salinization, with electrical conductivity ranging from 460 to 43,000μS·cm−1. The δ2H–δ18O signatures show mixing between seawater and freshwater components with long water residence time as evidenced by the lack of contribution from modern water using 3H, 14C and CFCs/SF6. S(SO4) isotopes also evidence seawater contribution but some signatures can be related to oxidation of pyrite and/or organically bounded S. In the upper layers 87Sr/86Sr ratios are close to that of seawater and then increase with depth, reflecting water–rock interaction with argillaceous formations while punctual low values reflect interaction with carbonate. Boron isotopes highlight secondary processes such as adsorption/desorption onto clays in addition to mixings. At the Barcarès site (120m deep), the high salinity in some layers appear to be related neither to present day seawater intrusion, nor to Salses-Leucate lagoonwater intrusion. Groundwater chemical composition thus highlights binary mixing between fresh groundwater and inherited salty water together with cation exchange processes, water–rock interactions and, locally, sedimentary organic matter mineralisation probably enhanced by pyrite oxidation. Finally, combining the results of this study and those of Caballero and Ladouche (2015), we discuss the possible future evolution of this aquifer system under global change, as well as the potential management strategies needed to preserve quantitatively and qualitatively this water resource. |
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ISSN |
0048-9697 |
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Call Number |
THL @ christoph.kuells @ Peteletgiraud2016398 |
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181 |
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Author |
Cary, L.; Petelet-Giraud, E.; Bertrand, G.; Kloppmann, W.; Aquilina, L.; Martins, V.; Hirata, R.; Montenegro, S.M.G.L.; Pauwels, H.; Chatton, E.; Franzen, Melissa; Aurouet, A.; Lasseur, E.; Picot-Colbeaux, G.; Guerrot, C.; Fléhoc, C.; Labasque, T.; Santos, Jeane Glaucia; Paiva, Anderson L.R.; Braibant, G.; Pierre, D. |
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Title |
Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): a multi-isotope approach |
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Journal Article |
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Year |
2015 |
Publication |
Science of the Total Environment |
Abbreviated Journal |
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Volume |
530-531 |
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Pages |
411-429 |
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Keywords |
Salinization origins; Salinization processes; Groundwater; Coastal aquifer; Strontium isotopes; Boron isotopes; Recife; Brazil |
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Elsevier |
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no |
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Call Number |
THL @ christoph.kuells @ cary:hal-01161949 |
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85 |
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Author |
Han, D.M.; Song, X.F.; Currell, M.J.; Yang, J.L.; Xiao, G.Q. |
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Title |
Chemical and isotopic constraints on evolution of groundwater salinization in the coastal plain aquifer of Laizhou Bay, China |
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Journal Article |
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Year |
2014 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
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Volume |
508 |
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Pages |
12-27 |
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Keywords |
Laizhou Bay, Coastal aquifers, Groundwater hydrochemistry, Stable isotopes, Saltwater intrusion |
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Abstract |
Summary A hydrochemical-isotopic investigation of the Laizhou Bay Quaternary aquifer in north China provides new insights into the hydrodynamic and geochemical relationships between freshwater, seawater and brine at different depths in coastal sediments. Saltwater intrusion mainly occurs due to two cones of depression caused by concentrated exploitation of fresh groundwater in the south, and brine water for salt production in the north. Groundwater is characterized by hydrochemical zonation of water types (ranging from Ca–HCO3 to Na–Cl) from south to north, controlled by migration and mixing of saline water bodies with the regional groundwater. The strong adherence of the majority of ion/Cl ratios to mixing lines between freshwater and saline water end-members (brine or seawater) indicates the importance of mixing under natural and/or anthropogenic influences. Examination of the groundwater stable isotope δ18O and δ2H values (between −9.5‰ and −3.0‰ and −75‰ and −40‰, respectively) and chloride contents (∼2 to 1000meq/L) of the groundwater indicate that the saline end-member is brine rather than seawater, and most groundwater samples plot on mixing trajectories between fresh groundwater (δ18O of between −6.0‰ and −9.0‰; Cl<5meq/L) and sampled brines (δ18O of approximately −3.0‰ and Cl>1000meq/L). Locally elevated Na/Cl ratios likely result from ion exchange in areas of long-term freshening. The brines, with radiocarbon activities of ∼30 to 60 pMC likely formed during the Holocene as a result of the sequence of transgression-regression and evaporation; while deep, fresh groundwater with depleted stable isotopic values (δ18O=−9.7‰ and δ2H=−71‰) and low radiocarbon activity (<20 pMC) was probably recharged during a cooler period in the late Pleistocene, as is common throughout northern China. An increase in the salinity and tritium concentration in some shallow groundwater sampled in the 1990s and re-sampled here indicates that intensive brine extraction has locally resulted in rapid mixing of young, fresh groundwater and saline brine. The δ18O and δ2H values of brines (∼−3.0‰ and −35‰) are much lower than that of modern seawater, which could be explained by 1) mixing of original (δ18O enriched) brine that was more saline than presently observed, with fresh groundwater recharged by precipitation and/or 2) dilution of the palaeo-seawater with continental runoff prior to and/or during brine formation. The first mechanism is supported by relatively high Br/Cl molar ratios (1.7×10−3–2.5×10−3) in brine water compared with ∼1.5×10−3 in seawater, which could indicate that the brines originally reached halite saturation and were subsequently diluted with fresher groundwater over the long-term. Decreasing 14C activities with increasing sampling depth and increasing proximity to the coastline indicate that the south coastal aquifer in Laizhou Bay is dominated by regional lateral flow, on millennial timescales. |
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0022-1694 |
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no |
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Call Number |
THL @ christoph.kuells @ Han201412 |
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174 |
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Author |
Di Lorenzo, T.; Galassi, D.M.P. |
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Title |
Agricultural impact on Mediterranean alluvial aquifers: do groundwater communities respond? |
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Journal Article |
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Year |
2013 |
Publication |
Fundamental and Applied Limnology/Archiv für Hydrobiologie |
Abbreviated Journal |
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182 |
Issue |
4 |
Pages |
271-282 |
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Keywords |
alluvial aquifers, groundwater, stygobiont, nitrate, overexploitation |
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Abstract |
In Mediterranean countries agricultural development heavily depends on groundwater availability due
to arid and semi-arid climate and poor surface-water resources. Agriculture represents one of the most relevant
pressures which generate impacts in alluvial aquifers by means of fertilizers and pesticides usage and groundwater
overexploitation. Until now, very few studies have addressed the ecological response of groundwater fauna to
groundwater contamination and overexploitation due to agricultural practices. We investigated a Mediterranean
alluvial aquifer heavily affected by nitrates contamination and groundwater abstraction stress due to crop irrigation. The aim of this study was to evaluate the sensitivity of groundwater communities to (a) groundwater nitrate
contamination, (b) groundwater abstraction due to irrigation practices, and (c) saltwater intrusion. The present
work suggests that nitrate concentration lower than 150 mg l
–1 is not an immediate threat to groundwater biodiversity in alluvial aquifers. This conclusion must be carefully considered in the light of the total lack of knowledge
of the effects of long-term nitrate pollution on the groundwater biota. Moreover, local extinctions of less tolerant
species, prior to monitoring, cannot be ruled out. Conversely, species abundances in ground water are affected by
groundwater withdrawal, but species richness may be less sensitive. This result is attributable to the disappearance
of saturated microhabitats and to the depletion of fine unconsolidated sediments, reducing the surface available
to bacterial biofilm, which represent the trophic resource for several groundwater invertebrates and where the
main aquifer self-purification processes, such as denitrification, take place. Saltwater intrusion seems not to affect
groundwater species at the values measured in this coastal aquifer. |
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E. Schweizerbart'sche Verlagsbuchhandlung |
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1863-9135 |
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Call Number |
THL @ luqianxue.zhang @ DiLorenzo2013 |
Serial |
43 |
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