Validity of a sharp-interface model in a confined coastal aquifer

Sakr, Sameh A.

doi:10.1007/s100400050187

Cited by 27 publications

(19 citation statements)

References 5 publications

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“…Fetter, 1972;Underwood et al, 1992;Stuyfzand, 1993;Sakr, 1999), the mixing zone in the seepage areas can be labelled as relatively wide compared to its depth. Therefore, the analytical and numerical approaches that assume a sharp interface and satisfactorily simulate BGH-lenses (e.g.…”

Section: Characteristics Of the Mixing Zone In Seepage Areasmentioning

confidence: 99%

“…Therefore, the analytical and numerical approaches that assume a sharp interface and satisfactorily simulate BGH-lenses (e.g. according to van der Veer, 1977;van Dam and Sikkema, 1982;Sikkema and van Dam, 1982;Sakr, 1999;Boekelman, 2001) should not be applied to these shallow rainwater lenses. As the mixing zones occur at shallow depth, their position and width is of great importance for the freshwater available for crop growth.…”

Section: Characteristics Of the Mixing Zone In Seepage Areasmentioning

confidence: 99%

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Shallow rainwater lenses in deltaic areas with saline seepage

Louw

Eeman

Siemon

et al. 2011

Hydrol. Earth Syst. Sci.

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Abstract. In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and size. Our findings are based on different types of field measurements and detailed numerical groundwater models applied in the south-western delta of the Netherlands. By combining the applied techniques we could extrapolate measurements at point scale (groundwater sampling, temperature and electrical soil conductivity (TEC)-probe measurements, electrical cone penetration tests (ECPT)) to field scale (continuous vertical electrical soundings (CVES), electromagnetic survey with EM31), and even to regional scale using helicopter-borne electromagnetic measurements (HEM). The measurements show a gradual mixing zone between infiltrating fresh rainwater and upward flowing saline groundwater. The mixing zone is best characterized by the depth of the centre of the mixing zone D mix , where the salinity is half that of seepage water, and the bottom of the mixing zone B mix , with a salinity equal to that of the seepage water (Cl-conc. 10 to 16 g l −1 ). D mix is found at very shallow depth in the confining top layer, on average at 1.7 m below ground level (b.g.l.), while B mix lies about 2.5 m b.g.l. The model results show that the constantly alternating upward and downward flow at low velocities in the confining layer is the main mechanism of mixing between rainwater and saline seepage and determines the position and extent of the mixing zone (D mix and B mix ). Recharge, seepage flux, and drainage depth are the controlling factors.

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Section: Characteristics Of the Mixing Zone In Seepage Areasmentioning

confidence: 99%

Section: Characteristics Of the Mixing Zone In Seepage Areasmentioning

confidence: 99%

Shallow rainwater lenses in deltaic areas with saline seepage

Louw

Eeman

Siemon

et al. 2011

Hydrol. Earth Syst. Sci.

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“…Processes and mechanisms of groundwater salinization in coastal areas have been the subject of research and investigation of several authors (Sakr 1999, Bear et al 2001, Das and Datta 2001, Oude Essink 2001, Grube et al 2002, Martinez and Bocanegra 2002, Trabelsi et al 2007, Kouzana et al 2010, Lachaal et al 2011. Most of them studied the occurrence of seawater intrusion based on modelling and simulation of the dynamic of interaction between saltwater and freshwater.…”

Section: Introductionmentioning

confidence: 99%

Hydrogeochemistry and groundwater salinization in an ephemeral coastal flood plain: Cap Bon, Tunisia

Chekirbane

Tsujimura

Kawachi

et al. 2013

Hydrological Sciences Journal

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The Wadi Al Ayn plain is a coastal system on the eastern coast of Cap Bon in northeastern Tunisia. The area is known for its intensive agriculture, which is based mainly on groundwater exploitation. The aim of this study is to identify the sources of groundwater salinization in the Wadi Al Ayn aquifer system and deduce the processes that drive the mineralization. Surface water and groundwater samples were taken and analysed for major ions and stable isotopes. The geochemical data were used to characterize and classify the water samples based on a variety of ion plots and diagrams. Stable isotopes are useful tools to help us understand recharge processes and to differentiate between salinity origins. The oilfield brines infiltrated from the sandy bed of Wadi Al Ayn comprise the main source of groundwater salinization in the central part of the plain, while seawater intrusion is mainly responsible for the increased salinity in the groundwater of the coastal part of the plain (at Daroufa).Key words hydrogeochemistry; stable isotopes; salinization; ephemeral coastal plain; Cap Bon; Tunisia Hydrogéochimie et salinisation des eaux souterraines d'une plaine côtière éphémère au Cap Bon, Tunisie Résumé La plaine de l'Oued Al Ayn est un système côtier appartenant à la côte orientale du Cap Bon au Nord-Est de la Tunisie. La zone est connue pour ses activités agricoles intensives principalement basées sur l'exploitation des eaux souterraines. L'objectif de ce travail est d'identifier les origines de la salinisation des eaux du système aquifère de la plaine de l'Oued Al Ayn et d'éclaircir ses mécanismes et ses processus. Les eaux de surface ainsi que les eaux souterraines ont été échantillonnées et analysées pour déterminer les teneurs des éléments chimiques majeurs et des isotopes stables. Ces données géochimiques ont servi à caractériser et classer les eaux échantillonnées en se basant sur de nombreux diagrammes et illustrations. Les isotopes stables constituent un outil efficace permettant de comprendre les processus de recharge et d'identifier les origines de la salinisation. Les saumures pétrolifères qui se sont infiltrées à travers le lit sableux de l'Oued Al Ayn constituent la cause majeure da la salinisation des eaux souterraines dans la partie centrale de la plaine, tandis que l'augmentation de la salinité des eaux souterraines dans la zone côtière de la plaine (Daroufa) est principalement due à l'intrusion marine.

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“…Up to 2007, many studies focused on situations with a relatively thin mixing zone between fresh and saline water relative to the lens thickness, justifying the assumption of a sharp interface, for example Souza (1987), andOude Essink (2001). The validity of assuming a sharp interface between fresh and saline water for coastal aquifers was discussed by Sakr (1999), who concluded that it is limited to cases with either a small dispersion to convection ratio or a large seepage factor (flux to conductivity ratio). However, the mixing zone in thin lenses is generally found to have a thickness of more than one meter according to De Louw et al (2013, Chapter 4 of this thesis), based on field measurements.…”

Section: Small But Important Systemsmentioning

confidence: 99%

“…Those solutions differ with regard to whether the saline water is considered to flow or to be stagnant. The validity of assuming a sharp interface for coastal aquifers was discussed by Sakr (1999) for confined aquifers, assuming a constant diffusion coefficient. He concluded that the sharp interface assumption only holds for a relatively small diffusion coefficient, which is disputable for the cases we consider here.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of rainwater lenses on upward seeping saline groundwater

Eeman¹

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Validity of a sharp-interface model in a confined coastal aquifer

Cited by 27 publications

References 5 publications

Shallow rainwater lenses in deltaic areas with saline seepage

Shallow rainwater lenses in deltaic areas with saline seepage

Hydrogeochemistry and groundwater salinization in an ephemeral coastal flood plain: Cap Bon, Tunisia

Dynamics of rainwater lenses on upward seeping saline groundwater

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