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Author | Sarker, M.M.R.; Van Camp, M.; Islam, M.; Ahmed, N.; Walraevens, K. | ||||
Title | Hydrochemistry in coastal aquifer of southwest Bangladesh : origin of salinity | Type | Journal Article | ||
Year | 2018 | Publication | Environmental Earth Sciences | Abbreviated Journal | |
Volume | 77 | Issue | 2 | Pages | 20 |
Keywords | Hydrochemistry,Stable isotope,Seawater intrusion,Coastal aquifer,Bangladesh,DAR-ES-SALAAM,SEAWATER INTRUSION,DELTA PLAIN,GROUNDWATER,DRINKING,TANZANIA,DROUGHT,COMPLEX | ||||
Abstract | In the coastal region of Bangladesh, groundwater is mainly used for domestic and agricultural purposes, but salinization of many groundwater resources limits its suitability for human consumption and practical application. This paper reports the results of a study that has mapped the salinity distribution in different aquifer layers up to a depth of 300 m in a region bordering the Bay of Bengal based on the main hydrochemistry and has investigated the origin of the salinity using Cl/Br ratios of the samples. The subsurface consists of a sequence of deltaic sediments with an alternation of more sandy and clayey sections in which several aquifer layers can be recognized. The main hydrochemistry shows different main water types in the different aquifers, indicating varying stages of freshening or salinization processes. The most freshwater, soft NaHCO3-type water with Cl concentrations mostly below 100 mg/l, is found in the deepest aquifer at 200-300 m below ground level (b.g.l.), in which the fresh/saltwater interface is pushed far to the south. Salinity is a main problem in the shallow aquifer systems, where Cl concentrations rise to nearly 8000 mg/l and the groundwater is mostly brackish NaCl water. Investigation of the Cl/Br ratios has shown that the source of the salinity in the deep aquifer is mixing with old connate seawater and that the saline waters in the more shallow aquifers do not originate from old connate water or direct seawater intrusion, but are derived from the dissolution of evaporite salts. These must have been formed in a tidal flat under influence of a strong seasonal precipitation pattern. Long dry seasons with high evaporation rates have evaporated seawater from inundated gullies and depressions, leading to salt precipitation, while subsequent heavy monsoon rains have dissolved the formed salts, and the solution has infiltrated in the subsoil, recharging groundwater. | ||||
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ISSN | 1866-6280 | ISBN | Medium | ||
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Notes | Approved | no | |||
Call Number | THL @ christoph.kuells @ Sarker2018 | Serial | 194 | ||
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Author | Siarkos, I.; Latinopoulos, P. | ||||
Title | Modeling seawater intrusion in overexploited aquifers in the absence of sufficient data: application to the aquifer of Nea Moudania, northern Greece | Type | Journal Article | ||
Year | 2016 | Publication | Hydrogeology Journal | Abbreviated Journal | Hydrogeology J. |
Volume | 24 | Issue | Pages | 2123–2141 | |
Keywords | Groundwater flow, Seawater intrusion, Numerical modeling, Greece, Sensitivity analysis | ||||
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 | ||||
Corporate Author | School of Civil Engineering, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece | Thesis | |||
Publisher | IAH | Place of Publication | Editor | Springer | |
Language | English | Summary Language | Original Title | ||
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Series Volume | Series Issue | Edition | |||
ISSN | 1431-2174 | ISBN | Medium | ||
Area | Hydrogeology; groundwater modelling, sea water intrusion | Expedition | Conference | ||
Notes | Approved | yes | |||
Call Number | MGRE @ redha.menani @ | Serial | 52 | ||
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Author | Zhao, Q.; Su, X.; Kang, B.; Zhang, Y.; Wu, X.; Liu, M. | ||||
Title | A hydrogeochemistry and multi-isotope (Sr, O, H, and C) study of groundwater salinity origin and hydrogeochemcial processes in the shallow confined aquifer of northern Yangtze River downstream coastal plain, China | Type | Journal Article | ||
Year | 2017 | Publication | Applied Geochemistry | Abbreviated Journal | |
Volume | 86 | Issue | Pages | 49-58 | |
Keywords | Coastal confined groundwater, Salinity, Hydrogeochemcial processes, Multiple environmental tracers | ||||
Abstract | Economically developed coastal areas have a high water demand, and their groundwater resources can be threatened by salinization. Many methods and tracers have been used to discriminate the source of salinization because a single method does not yield reliable results. In this paper, the shallow confined coastal plain aquifer, north of the downstream Yangtze River in China, is used as a case study to investigate the origin of the salinity and the relevant geochemical processes for this aquifer. Multiple environmental tracers of major ions, minor ions (Br−, I−), and isotopes (18O, 2H, 13C, 87Sr, 3H, 14C) were used so as to provide reliable conclusions. The TDS distribution of the aquifer has an increasing trend, from below 500 mg/L in the inland areas to more than 20,000 mg/L around the southeast coastline. The water chemical type evolves from HCO3-Ca to Cl-Na as the TDS increases. The results suggest that the groundwater salinity is influenced by seawater intrusion. The seawater proportions in the groundwater samples range from 0.07% to 94.41% and show the same spatial distribution pattern as TDS. The 3H and 14C values show that the highest salinity was mainly caused by a seawater transgression around 6000a B.P. The aquifer is also affected by other hydrogeochemical processes: base exchange has enriched Ca2+ and depleted K+ and Na+, sulfate reduction has reduced the concentration of SO42− and enriched HCO3−, and iodine-rich organic matter decomposition has enriched the concentration of I−. The iodine enrichment also suggests paleo-seawater intrusion. In addition, the precipitation of carbonate minerals has decreased the concentration of Ca2+, Mg2+, and HCO3−, albeit to a limited extent. | ||||
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ISSN | 0883-2927 | ISBN | Medium | ||
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Notes | Approved | no | |||
Call Number | THL @ christoph.kuells @ Zhao201749 | Serial | 182 | ||
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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. | ||||
Title | Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): a multi-isotope approach | Type | Journal Article | ||
Year | 2015 | Publication | Science of the Total Environment | Abbreviated Journal | |
Volume | 530-531 | Issue | Pages | 411-429 | |
Keywords | Salinization origins; Salinization processes; Groundwater; Coastal aquifer; Strontium isotopes; Boron isotopes; Recife; Brazil | ||||
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Publisher | Elsevier | Place of Publication | Editor | ||
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Notes | Approved | no | |||
Call Number | THL @ christoph.kuells @ cary:hal-01161949 | Serial | 85 | ||
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Author | Han, D.M.; Song, X.F.; Currell, M.J.; Yang, J.L.; Xiao, G.Q. | ||||
Title | Chemical and isotopic constraints on evolution of groundwater salinization in the coastal plain aquifer of Laizhou Bay, China | Type | Journal Article | ||
Year | 2014 | Publication | Journal of Hydrology | Abbreviated Journal | |
Volume | 508 | Issue | Pages | 12-27 | |
Keywords | Laizhou Bay, Coastal aquifers, Groundwater hydrochemistry, Stable isotopes, Saltwater intrusion | ||||
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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ISSN | 0022-1694 | ISBN | Medium | ||
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Notes | Approved | no | |||
Call Number | THL @ christoph.kuells @ Han201412 | Serial | 174 | ||
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