SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3808) / INIST... more SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3808) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Les préoccupartions des physiciens de l'atmosphère et des climatologues rejoignent celles des... more Les préoccupartions des physiciens de l'atmosphère et des climatologues rejoignent celles des hydrologues continentaux d'une part parce que le cycle de l'eau joue un rôle fondamental dans les bilans d'énergie de l'atmosphère elle-même, en particulier dans les tropiques, d'autre part en raison de la nécessité de comprendre et de représenter convenablement les échanges à la surface. Cependant les échelles abordées sont généralement différentes. Une rencontre plus étroite des deux domaines est souhaitable, au prix d'une adaptation des objectifs de chacun : les modèles météorologiques mésoéchelle, les radars météorologiques... peuvent atteindre des échelles applicables à l'hydrologie ; tandis que les bilans hydrologiques intégrés à plus grande échelle, utilisables dans des modèles de circulation générale, doivent pouvoir être établis en combinant télédétection et modélisation hydrologique. Pour parvenir à ces objectifs, deux types d'expérimentation sont nécessaires : une expérimentation "mésoéchelle", portant sur des régions et des périodes de temps relativement courtes, et combinant mesures hydrologiques et mesures atmosphériques ; une expérimentation "grande échelle", portant sur de plus vastes régions et des périodes beaucoup plus longues, visant à établir des bilans à l'échelle de quelques mailles de modèles de circulation générale atmosphérique. Dans ce dernier cas, ainsi que pour les échelles intermédiaires, la télédétection a un rôle important à jouer. Ses possibilités actuelles sont limitées, mais seront complétées par de nouvelles missions satellitaires. (Résumé d'auteur
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1998
Laboratoire degiocbimie isotopique et depalkoclimatologie, .&Cole nationale d'ing&ieurs de Sfm, r... more Laboratoire degiocbimie isotopique et depalkoclimatologie, .&Cole nationale d'ing&ieurs de Sfm, route de Soukra, BP W; 3038 Sfax, Tunisie ' Dipatiement de giographie, faculth des lettres et des sciences humaines. bd du 9-a&l, Tunis, Tunisie
Sustainable groundwater management strategies in water-scarce countries need to guide future deci... more Sustainable groundwater management strategies in water-scarce countries need to guide future decision-making processes pragmatically, by simultaneously considering local needs, environmental problems and economic development. The socio-hydrogeological approach named ‘Bir Al-Nas’ has been tested in the Grombalia region (Cap Bon Peninsula, Tunisia), to evaluate the effectiveness of complementing hydrogeochemical and hydrogeological investigations with the social dimension of the issue at stake (which, in this case, is the identification of groundwater pollution sources). Within this approach, the social appraisal, performed through social network analysis and public engagement of water end-users, allowed hydrogeologists to get acquainted with the institutional dimension of local groundwater management, identifying issues, potential gaps (such as weak knowledge transfer among concerned stakeholders), and the key actors likely to support the implementation of the new science-based management practices resulting from the ongoing hydrogeological investigation. Results, hence, go beyond the specific relevance for the Grombaila basin, showing the effectiveness of the proposed approach and the importance of including social assessment in any given hydrogeological research aimed at supporting local development through groundwater protection measures.RésuméLes futurs processus de prise de décision ont besoin d’être guidés par des stratégies de gestion durable des eaux souterraines dans les pays à faibles ressources en eau, en considérant simultanément les besoins locaux, les problèmes environnementaux et le développement économique. L’approche socio-hydrogéologique nommée « Bir Al-Nas » a été testée dans la région de Grombalia (Péninsule du cap Bon, Tunisie) afin d’évaluer l’efficacité de la complémentarité des études hydrogéologiques et hydrogéochimiques avec la dimension sociale de l’enjeu (qui, dans ce cas, est l’identification des sources de pollution des eaux souterraines). Dans le cadre de cette approche, l’évaluation sociale est effectuée par une analyse du réseau social et de l’engagement public des utilisateurs finaux de l’eau. Elle a permis aux hydrogéologues de connaître la dimension institutionnelle de la gestion locale des eaux souterraines, d’identifier les sujets à enjeux, les potentiels écarts (tels que les faiblesses de transfert de connaissance parmi les acteurs concernés) et les acteurs clés susceptibles de soutenir la mise en œuvre de nouvelles pratiques de gestion fondées scientifiquement et résultant des études hydrogéologiques en cours. Les résultats vont par conséquent au-delà de la pertinence spécifique pour le bassin de Grombalia. Ils montrent l’efficacité de l’approche proposée et l’importance d’inclure l’évaluation sociale dans toute recherche hydrogéologique ayant pour objectif de soutenir le développement local par des mesures de protection des eaux souterraines.ResumenLas estrategias de gestión sostenible del agua subterránea en los países con escasez de agua deben orientar los procesos de toma de decisiones en el futuro de forma pragmática, considerando simultáneamente las necesidades locales, los problemas ambientales y el desarrollo económico. En la región de Grombalia (Península de Cap Bon, Túnez) se ha puesto a prueba el enfoque socio-hidrogeológico denominado ‘Bir Al-Nas’, para evaluar la eficacia de complementar las investigaciones hidrogeoquímicas e hidrogeológicas con la dimensión social de la cuestión de interés (en este caso, es la identificación de las fuentes de contaminación del agua subterránea). Dentro de este enfoque, la evaluación social, realizada a través del análisis de la red social y el compromiso público de los usuarios finales del agua, permitió a los hidrogeólogos familiarizarse con la dimensión institucional de la gestión local del agua subterránea, identificando problemas, brechas potenciales (como una débil transferencia de conocimiento entre las partes interesadas) y los actores clave que probablemente apoyen la implementación de las nuevas prácticas científicas de manejo basadas en los resultados de la investigación hidrogeológica en curso. Los resultados, por lo tanto, van más allá de la relevancia específica para la cuenca de Grombaila, mostrando la efectividad del enfoque propuesto y la importancia de incluir a la evaluación social en cualquier investigación hidrogeológica destinada a apoyar el desarrollo local a través de medidas de protección del agua subterránea.摘要缺水国家的可持续地下水管理策略需要同时考虑当地需求、环境问题和经济发展来指引未来决策过程。在古兰巴利耶地区试验了被称为“Bir Al-Nas”的社会-水文地质方法,以评估在社会问题(在本研究案例中,问题就是地下水污染源的确定)岌岌可危的情况下补充水文化学调查和水文地质调查的有效性。在这个方法中,通过社会网络分析进行的社会评估及水最终用户的公共参与可以使水文地质工作者认识当地地下水管理的组织层面、需确定的问题、潜在的差距(如相关的利害关系人)及关键的活动者有可能支持在进行的水文地质调查中实施基于新科学的管理实践。因此,结果超出了古兰巴利耶流域特定的相关性,显示出了所提出方法的有效性及在任何旨在通过地下水保护措施支持当地发展的特定水文地质研究中的重要性。RiassuntoNei Paesi caratterizzati da problemi di scarsità idrica è necessario che le strategie di gestione sostenibile delle acque sotterranee influenzino i processi…
F. Agterberg W. Ambrose H. Asadi Haroni A.D. Bas E. Bedini P. Behnia A. Boluwade M. Brandmeier A.... more F. Agterberg W. Ambrose H. Asadi Haroni A.D. Bas E. Bedini P. Behnia A. Boluwade M. Brandmeier A. Cancelliere E.J.M. Carranza E. Chanda S. Chatterjee N. Chkir A. Ciampalini T. Coburn D. Cohen J. Combs A. Comunian B. Coto J. Davis C. Deutsch B. Elliott X. Emery A. Esmaeili A. Förster N. Freitag D. Gerard M. Gettings M. Gonçalves E. Grunsky J. Harris E. Haryono F. Hein M. Höök M. Icardi R.V. Ingersoll S. Jafari Behbahani M. Jalali S. Kanchibota K. Koike R. Kouda A. Kovscek O. Kreuzer M. Kumral J. Laherrere J.-Y. Lee J.F.C. Leite Costa Y. Liu K. Long D. Machuca-Mory H. Mahmoud B. Marchant S. McCoy D. McKinney P. McShane S. Michaelides A. Mokhtari L.R. Monteiro U. Mueller I.N. Myagkaya V. Nykänen B. Ogunyomi R. Olea Y. Ozcelik G. Partington J. Pashin A. Patiño-Douce D. Pedretti A. Porwal S. Purwar A.L. Ramanathan H. Ranjbar F. Rashidi-Nejad K. Rokni D. Rosbjerg M. Sadeghi J. Sample E. Shamir M. Sharma D. Singer A. Skabar E. Tercan H. Thompson
Hydrochemical and environmental isotope tracers have been used to identify the geochemical proces... more Hydrochemical and environmental isotope tracers have been used to identify the geochemical processes that affect groundwater masses in the aquifer system of Grombalia (northeastern Tunisia). The study area presents a multilayer aquifer system logged in the Quaternary and Miocene sandstones. Multi-tracer results show that the dissolution of evaporite minerals as well as the evaporation and the irrigation return flow are the main processes controlling groundwater quality. The isotopic data proves the origin of different groundwater masses as well as the natural and anthropogenic processes that control their mineralization.
Calcareous deposits, mainly consisting of mollusc shell accumulations, which have been dated by t... more Calcareous deposits, mainly consisting of mollusc shell accumulations, which have been dated by the U/Th disequilibrium method, mark the shorelines of paleolake highstands in the Great Chotts Area of Southern Tunisia. The 5 sites studied consist of discontinuous accumulations of fossils of marine-like organisms e.g.: Cerastoderma glaucum, Melania tuberculata, Melanopsis praemorsa, Cerithium rupestre. U/Th isochron plots and age frequency histograms for 39 shell samples are reported here. Limited variations for U content and 234U/238U activity ratios (AR) of shells support the hypothesis of closure of the geochemical system with respect to this element. It is remarkable that 234U/238U AR of shells collected in Chott Fejej or Chott Jerid are clustered around different values, reflecting probably different groundwater recharge from the Continental Intercalaire (CI) or Complexe Terminal (CT) aquifers. Furthermore waters collected near Wadi el Akarit show 234U/238U AR values comparable t...
The last deglaciation and its climatic events, such as the Bølling-Allerød (BA) and the Younger-D... more The last deglaciation and its climatic events, such as the Bølling-Allerød (BA) and the Younger-Dryas (YD), have been clearly recorded in the d 13 C profiles of three stalagmites from caves from Southern France to Northern Tunisia. The three d 13 C records, dated by thermal ionization mass spectrometric uranium-thorium method (TIMS), show great synchroneity and similarity in shape with the Chinese cave d 18 O records and with the marine tropical records, leading to the hypothesis of an in-phase (between 15.5 and 16 ka $70.5 ka) postglacial warming in the Northern Hemisphere, up to at least 451N. The BA transition appears more gradual in the speleothem records than in the Greenland records and the Allerød seems warmer than the Bølling, showing here close similarities with other marine and continental archives. A North-South gradient is observed in the BA trend: it cools in Greenland and warms in our speleothem records. Several climatic events are clearly recognizable: a cooler period at about 14 ka (Older Dryas (OD)); the Intra-Allerød Cold Period at about $13.3 ka; the YD cooling onset between 12.7 and 12.970.3 ka. Similar to the BA, the YD displays a gradual climate amelioration just after its onset at 12.7570.25 ka, up to the Preboreal, and is punctuated by a short climatic event at 12.15 ka.
Water in the fissured limestone and dolomite of the Turonian aquifer of Tunisia has been investig... more Water in the fissured limestone and dolomite of the Turonian aquifer of Tunisia has been investigated using geochemical (major ions) and isotopic (δ 18 O, δ 2 H, 14 C) data. To carry out a characterization of aquifer behaviour, 48 representative samples were collected at the end of the humid season. The evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium, chloride and sulphate contents as a result of leaching of evaporite rock. In the study, three distinct chemical trends in groundwater were identified. The major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories: (1) calcite precipitation, (2) gypsum and halite dissolution, and (3) ion exchange. The stable isotope composition of water samples indicates largescale interaction between the Continental Intercalaire and the Turonian aquifer and the presence of a young local component which probably enters the system via faults and/or fractures.
Journal of Resources Development and Management, 2014
Arid and semi-arid areas are threatened by desertification, and thus the degradation due to vario... more Arid and semi-arid areas are threatened by desertification, and thus the degradation due to various factors, including drought, of course, but also the exploitation of resources. They are, in fact, already in a state of stress (resources less than 500 m 3 per year per capita) with important disorders induced by climate change. These make an impact on the hydrological cycle, with longer droughts and increased flooding. These disorders will strengthen the already observed degradation of ecosystems, which are often overexploited. Essaouira synclinal area is part of the semi-arid areas of Morocco that are subject to the impact of climatic and human pressures. In the case of this coastal area, which includes two main aquifers superimposed; the Plio-Quaternary and Turonian, the resulting vulnerability is compounded by the risk of infiltration navy. The Rainfall in the area does not exceed 300 mm year-1 , the average temperature hovers around 20 °C, the piezometric map of Essaouira synclinal basin was made, different water samples have been collected from October 2009 after exceptional rainfall, all waters are sodium-chloride facies, interpretation of mineralization indicates power by the Ksob Wadi in the northeast and increasing levels of chlorides in the central part generated by the Essaouira diaper hidden. Excessive levels of nitrates have been identified, as well as chlorides after rains of winter 2009. The electrical conductivity and concentrations of 18 O and 2 H were measured, a local meteoric water line was determined according to the Atlantic origin of precipitation. However, the water Turonian, characterized by significant resources, demonstrates a very low charging current; its vulnerability would be more related to human pressure than changes in climatic conditions. The Essaouira Basin is more vulnerable to drought because its climate is entirely dependent on recharge meteoric waters.
Stable isotopes (δ 2 H, δ 18 O and δ 13 C) and radiocarbon (14 C) have been used in conjunction w... more Stable isotopes (δ 2 H, δ 18 O and δ 13 C) and radiocarbon (14 C) have been used in conjunction with chemical data to evaluate recharge mechanisms and groundwater residence time, and to identify inter-aquifer mixing in the Djeffara multi-aquifer in semi-arid southeastern Tunisia. The southern part of this basin, the Djeffara of Medenine aquifer system, is comprised of two main aquifers of Triassic and Miocene sandstone. The Triassic aquifer presents two compartments; the first one (west of the Medenine fault system) is unconfined with a well-defined isotope fingerprint; the second compartment is deeper and confined. Multi-tracer results show groundwater of different origins, ages and salinities, and that tectonic features control groundwater flows. Fresh and brackish groundwater from the unconfined part of the Triassic aquifer was mostly recharged during the Holocene. The recharge rates of this aquifer, inferred by 14 C ages, are variable and could reach 3.5mm/year. Brackish water of the deep confined part of the Triassic aquifer has stable isotope composition and 14 C content that indicates earlier recharge during late Pleistocene cold periods. Brackish to saline water of the Miocene aquifer presents variable isotope composition. Groundwater flowing through the Medenine fault system is mainly feeding the Miocene aquifer rather than the deep confined part of the Triassic aquifer.
Environmental tracers ((2)H, (18)O, isotopes of Uranium) and geochemical processes occurring with... more Environmental tracers ((2)H, (18)O, isotopes of Uranium) and geochemical processes occurring within groundwaters from the Continental Intercalaire (CI) in Southern Tunisia were used to understand the hydrodynamics and the recharge conditions of this aquifer. This study investigates the chemical and isotopic compositions of the CI groundwater. The water types are dominated by Na(+), SO4(2-), Cl(-) throughout most of the basin with a general increase in total dissolved solids from the Saharan Platform margins towards the Chotts region. Large scale groundwater flow paths are toward the Chotts region. The stable isotopes composition of the analyzed groundwater ranges from -8.8 to -6‰ vs V-SMOW for δ(18)O and from -67 to -40‰ vs V-SMOW for δ(2)H. The relatively enriched stable isotopes contents suggest the contribution of the Dahar sandstones outcrops in the current recharge of the CI aquifer in an arid context. However, the most depleted values in heavy isotopes indicate a paleorecharge of the aquifer under wetter conditions revealing a long residence time of groundwaters. The results from water samples using alpha spectrometry method indicate a range in (238)U concentrations and (234)U/(238)U activity ratios (AR) of 0.044-1.285 μg kg(-1) and 1.2 to 8.84 respectively. The geochemistry of uranium isotopes in groundwater is controlled by many factors, essentially, the influence of water rock interactions, the preferential dissolution of (234)U relative to (238)U due to alpha recoil and the mixing processes between different waters with distinct AR as well as (238)U concentrations.
SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3808) / INIST... more SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3808) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Les préoccupartions des physiciens de l'atmosphère et des climatologues rejoignent celles des... more Les préoccupartions des physiciens de l'atmosphère et des climatologues rejoignent celles des hydrologues continentaux d'une part parce que le cycle de l'eau joue un rôle fondamental dans les bilans d'énergie de l'atmosphère elle-même, en particulier dans les tropiques, d'autre part en raison de la nécessité de comprendre et de représenter convenablement les échanges à la surface. Cependant les échelles abordées sont généralement différentes. Une rencontre plus étroite des deux domaines est souhaitable, au prix d'une adaptation des objectifs de chacun : les modèles météorologiques mésoéchelle, les radars météorologiques... peuvent atteindre des échelles applicables à l'hydrologie ; tandis que les bilans hydrologiques intégrés à plus grande échelle, utilisables dans des modèles de circulation générale, doivent pouvoir être établis en combinant télédétection et modélisation hydrologique. Pour parvenir à ces objectifs, deux types d'expérimentation sont nécessaires : une expérimentation "mésoéchelle", portant sur des régions et des périodes de temps relativement courtes, et combinant mesures hydrologiques et mesures atmosphériques ; une expérimentation "grande échelle", portant sur de plus vastes régions et des périodes beaucoup plus longues, visant à établir des bilans à l'échelle de quelques mailles de modèles de circulation générale atmosphérique. Dans ce dernier cas, ainsi que pour les échelles intermédiaires, la télédétection a un rôle important à jouer. Ses possibilités actuelles sont limitées, mais seront complétées par de nouvelles missions satellitaires. (Résumé d'auteur
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1998
Laboratoire degiocbimie isotopique et depalkoclimatologie, .&Cole nationale d'ing&ieurs de Sfm, r... more Laboratoire degiocbimie isotopique et depalkoclimatologie, .&Cole nationale d'ing&ieurs de Sfm, route de Soukra, BP W; 3038 Sfax, Tunisie ' Dipatiement de giographie, faculth des lettres et des sciences humaines. bd du 9-a&l, Tunis, Tunisie
Sustainable groundwater management strategies in water-scarce countries need to guide future deci... more Sustainable groundwater management strategies in water-scarce countries need to guide future decision-making processes pragmatically, by simultaneously considering local needs, environmental problems and economic development. The socio-hydrogeological approach named ‘Bir Al-Nas’ has been tested in the Grombalia region (Cap Bon Peninsula, Tunisia), to evaluate the effectiveness of complementing hydrogeochemical and hydrogeological investigations with the social dimension of the issue at stake (which, in this case, is the identification of groundwater pollution sources). Within this approach, the social appraisal, performed through social network analysis and public engagement of water end-users, allowed hydrogeologists to get acquainted with the institutional dimension of local groundwater management, identifying issues, potential gaps (such as weak knowledge transfer among concerned stakeholders), and the key actors likely to support the implementation of the new science-based management practices resulting from the ongoing hydrogeological investigation. Results, hence, go beyond the specific relevance for the Grombaila basin, showing the effectiveness of the proposed approach and the importance of including social assessment in any given hydrogeological research aimed at supporting local development through groundwater protection measures.RésuméLes futurs processus de prise de décision ont besoin d’être guidés par des stratégies de gestion durable des eaux souterraines dans les pays à faibles ressources en eau, en considérant simultanément les besoins locaux, les problèmes environnementaux et le développement économique. L’approche socio-hydrogéologique nommée « Bir Al-Nas » a été testée dans la région de Grombalia (Péninsule du cap Bon, Tunisie) afin d’évaluer l’efficacité de la complémentarité des études hydrogéologiques et hydrogéochimiques avec la dimension sociale de l’enjeu (qui, dans ce cas, est l’identification des sources de pollution des eaux souterraines). Dans le cadre de cette approche, l’évaluation sociale est effectuée par une analyse du réseau social et de l’engagement public des utilisateurs finaux de l’eau. Elle a permis aux hydrogéologues de connaître la dimension institutionnelle de la gestion locale des eaux souterraines, d’identifier les sujets à enjeux, les potentiels écarts (tels que les faiblesses de transfert de connaissance parmi les acteurs concernés) et les acteurs clés susceptibles de soutenir la mise en œuvre de nouvelles pratiques de gestion fondées scientifiquement et résultant des études hydrogéologiques en cours. Les résultats vont par conséquent au-delà de la pertinence spécifique pour le bassin de Grombalia. Ils montrent l’efficacité de l’approche proposée et l’importance d’inclure l’évaluation sociale dans toute recherche hydrogéologique ayant pour objectif de soutenir le développement local par des mesures de protection des eaux souterraines.ResumenLas estrategias de gestión sostenible del agua subterránea en los países con escasez de agua deben orientar los procesos de toma de decisiones en el futuro de forma pragmática, considerando simultáneamente las necesidades locales, los problemas ambientales y el desarrollo económico. En la región de Grombalia (Península de Cap Bon, Túnez) se ha puesto a prueba el enfoque socio-hidrogeológico denominado ‘Bir Al-Nas’, para evaluar la eficacia de complementar las investigaciones hidrogeoquímicas e hidrogeológicas con la dimensión social de la cuestión de interés (en este caso, es la identificación de las fuentes de contaminación del agua subterránea). Dentro de este enfoque, la evaluación social, realizada a través del análisis de la red social y el compromiso público de los usuarios finales del agua, permitió a los hidrogeólogos familiarizarse con la dimensión institucional de la gestión local del agua subterránea, identificando problemas, brechas potenciales (como una débil transferencia de conocimiento entre las partes interesadas) y los actores clave que probablemente apoyen la implementación de las nuevas prácticas científicas de manejo basadas en los resultados de la investigación hidrogeológica en curso. Los resultados, por lo tanto, van más allá de la relevancia específica para la cuenca de Grombaila, mostrando la efectividad del enfoque propuesto y la importancia de incluir a la evaluación social en cualquier investigación hidrogeológica destinada a apoyar el desarrollo local a través de medidas de protección del agua subterránea.摘要缺水国家的可持续地下水管理策略需要同时考虑当地需求、环境问题和经济发展来指引未来决策过程。在古兰巴利耶地区试验了被称为“Bir Al-Nas”的社会-水文地质方法,以评估在社会问题(在本研究案例中,问题就是地下水污染源的确定)岌岌可危的情况下补充水文化学调查和水文地质调查的有效性。在这个方法中,通过社会网络分析进行的社会评估及水最终用户的公共参与可以使水文地质工作者认识当地地下水管理的组织层面、需确定的问题、潜在的差距(如相关的利害关系人)及关键的活动者有可能支持在进行的水文地质调查中实施基于新科学的管理实践。因此,结果超出了古兰巴利耶流域特定的相关性,显示出了所提出方法的有效性及在任何旨在通过地下水保护措施支持当地发展的特定水文地质研究中的重要性。RiassuntoNei Paesi caratterizzati da problemi di scarsità idrica è necessario che le strategie di gestione sostenibile delle acque sotterranee influenzino i processi…
F. Agterberg W. Ambrose H. Asadi Haroni A.D. Bas E. Bedini P. Behnia A. Boluwade M. Brandmeier A.... more F. Agterberg W. Ambrose H. Asadi Haroni A.D. Bas E. Bedini P. Behnia A. Boluwade M. Brandmeier A. Cancelliere E.J.M. Carranza E. Chanda S. Chatterjee N. Chkir A. Ciampalini T. Coburn D. Cohen J. Combs A. Comunian B. Coto J. Davis C. Deutsch B. Elliott X. Emery A. Esmaeili A. Förster N. Freitag D. Gerard M. Gettings M. Gonçalves E. Grunsky J. Harris E. Haryono F. Hein M. Höök M. Icardi R.V. Ingersoll S. Jafari Behbahani M. Jalali S. Kanchibota K. Koike R. Kouda A. Kovscek O. Kreuzer M. Kumral J. Laherrere J.-Y. Lee J.F.C. Leite Costa Y. Liu K. Long D. Machuca-Mory H. Mahmoud B. Marchant S. McCoy D. McKinney P. McShane S. Michaelides A. Mokhtari L.R. Monteiro U. Mueller I.N. Myagkaya V. Nykänen B. Ogunyomi R. Olea Y. Ozcelik G. Partington J. Pashin A. Patiño-Douce D. Pedretti A. Porwal S. Purwar A.L. Ramanathan H. Ranjbar F. Rashidi-Nejad K. Rokni D. Rosbjerg M. Sadeghi J. Sample E. Shamir M. Sharma D. Singer A. Skabar E. Tercan H. Thompson
Hydrochemical and environmental isotope tracers have been used to identify the geochemical proces... more Hydrochemical and environmental isotope tracers have been used to identify the geochemical processes that affect groundwater masses in the aquifer system of Grombalia (northeastern Tunisia). The study area presents a multilayer aquifer system logged in the Quaternary and Miocene sandstones. Multi-tracer results show that the dissolution of evaporite minerals as well as the evaporation and the irrigation return flow are the main processes controlling groundwater quality. The isotopic data proves the origin of different groundwater masses as well as the natural and anthropogenic processes that control their mineralization.
Calcareous deposits, mainly consisting of mollusc shell accumulations, which have been dated by t... more Calcareous deposits, mainly consisting of mollusc shell accumulations, which have been dated by the U/Th disequilibrium method, mark the shorelines of paleolake highstands in the Great Chotts Area of Southern Tunisia. The 5 sites studied consist of discontinuous accumulations of fossils of marine-like organisms e.g.: Cerastoderma glaucum, Melania tuberculata, Melanopsis praemorsa, Cerithium rupestre. U/Th isochron plots and age frequency histograms for 39 shell samples are reported here. Limited variations for U content and 234U/238U activity ratios (AR) of shells support the hypothesis of closure of the geochemical system with respect to this element. It is remarkable that 234U/238U AR of shells collected in Chott Fejej or Chott Jerid are clustered around different values, reflecting probably different groundwater recharge from the Continental Intercalaire (CI) or Complexe Terminal (CT) aquifers. Furthermore waters collected near Wadi el Akarit show 234U/238U AR values comparable t...
The last deglaciation and its climatic events, such as the Bølling-Allerød (BA) and the Younger-D... more The last deglaciation and its climatic events, such as the Bølling-Allerød (BA) and the Younger-Dryas (YD), have been clearly recorded in the d 13 C profiles of three stalagmites from caves from Southern France to Northern Tunisia. The three d 13 C records, dated by thermal ionization mass spectrometric uranium-thorium method (TIMS), show great synchroneity and similarity in shape with the Chinese cave d 18 O records and with the marine tropical records, leading to the hypothesis of an in-phase (between 15.5 and 16 ka $70.5 ka) postglacial warming in the Northern Hemisphere, up to at least 451N. The BA transition appears more gradual in the speleothem records than in the Greenland records and the Allerød seems warmer than the Bølling, showing here close similarities with other marine and continental archives. A North-South gradient is observed in the BA trend: it cools in Greenland and warms in our speleothem records. Several climatic events are clearly recognizable: a cooler period at about 14 ka (Older Dryas (OD)); the Intra-Allerød Cold Period at about $13.3 ka; the YD cooling onset between 12.7 and 12.970.3 ka. Similar to the BA, the YD displays a gradual climate amelioration just after its onset at 12.7570.25 ka, up to the Preboreal, and is punctuated by a short climatic event at 12.15 ka.
Water in the fissured limestone and dolomite of the Turonian aquifer of Tunisia has been investig... more Water in the fissured limestone and dolomite of the Turonian aquifer of Tunisia has been investigated using geochemical (major ions) and isotopic (δ 18 O, δ 2 H, 14 C) data. To carry out a characterization of aquifer behaviour, 48 representative samples were collected at the end of the humid season. The evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium, chloride and sulphate contents as a result of leaching of evaporite rock. In the study, three distinct chemical trends in groundwater were identified. The major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories: (1) calcite precipitation, (2) gypsum and halite dissolution, and (3) ion exchange. The stable isotope composition of water samples indicates largescale interaction between the Continental Intercalaire and the Turonian aquifer and the presence of a young local component which probably enters the system via faults and/or fractures.
Journal of Resources Development and Management, 2014
Arid and semi-arid areas are threatened by desertification, and thus the degradation due to vario... more Arid and semi-arid areas are threatened by desertification, and thus the degradation due to various factors, including drought, of course, but also the exploitation of resources. They are, in fact, already in a state of stress (resources less than 500 m 3 per year per capita) with important disorders induced by climate change. These make an impact on the hydrological cycle, with longer droughts and increased flooding. These disorders will strengthen the already observed degradation of ecosystems, which are often overexploited. Essaouira synclinal area is part of the semi-arid areas of Morocco that are subject to the impact of climatic and human pressures. In the case of this coastal area, which includes two main aquifers superimposed; the Plio-Quaternary and Turonian, the resulting vulnerability is compounded by the risk of infiltration navy. The Rainfall in the area does not exceed 300 mm year-1 , the average temperature hovers around 20 °C, the piezometric map of Essaouira synclinal basin was made, different water samples have been collected from October 2009 after exceptional rainfall, all waters are sodium-chloride facies, interpretation of mineralization indicates power by the Ksob Wadi in the northeast and increasing levels of chlorides in the central part generated by the Essaouira diaper hidden. Excessive levels of nitrates have been identified, as well as chlorides after rains of winter 2009. The electrical conductivity and concentrations of 18 O and 2 H were measured, a local meteoric water line was determined according to the Atlantic origin of precipitation. However, the water Turonian, characterized by significant resources, demonstrates a very low charging current; its vulnerability would be more related to human pressure than changes in climatic conditions. The Essaouira Basin is more vulnerable to drought because its climate is entirely dependent on recharge meteoric waters.
Stable isotopes (δ 2 H, δ 18 O and δ 13 C) and radiocarbon (14 C) have been used in conjunction w... more Stable isotopes (δ 2 H, δ 18 O and δ 13 C) and radiocarbon (14 C) have been used in conjunction with chemical data to evaluate recharge mechanisms and groundwater residence time, and to identify inter-aquifer mixing in the Djeffara multi-aquifer in semi-arid southeastern Tunisia. The southern part of this basin, the Djeffara of Medenine aquifer system, is comprised of two main aquifers of Triassic and Miocene sandstone. The Triassic aquifer presents two compartments; the first one (west of the Medenine fault system) is unconfined with a well-defined isotope fingerprint; the second compartment is deeper and confined. Multi-tracer results show groundwater of different origins, ages and salinities, and that tectonic features control groundwater flows. Fresh and brackish groundwater from the unconfined part of the Triassic aquifer was mostly recharged during the Holocene. The recharge rates of this aquifer, inferred by 14 C ages, are variable and could reach 3.5mm/year. Brackish water of the deep confined part of the Triassic aquifer has stable isotope composition and 14 C content that indicates earlier recharge during late Pleistocene cold periods. Brackish to saline water of the Miocene aquifer presents variable isotope composition. Groundwater flowing through the Medenine fault system is mainly feeding the Miocene aquifer rather than the deep confined part of the Triassic aquifer.
Environmental tracers ((2)H, (18)O, isotopes of Uranium) and geochemical processes occurring with... more Environmental tracers ((2)H, (18)O, isotopes of Uranium) and geochemical processes occurring within groundwaters from the Continental Intercalaire (CI) in Southern Tunisia were used to understand the hydrodynamics and the recharge conditions of this aquifer. This study investigates the chemical and isotopic compositions of the CI groundwater. The water types are dominated by Na(+), SO4(2-), Cl(-) throughout most of the basin with a general increase in total dissolved solids from the Saharan Platform margins towards the Chotts region. Large scale groundwater flow paths are toward the Chotts region. The stable isotopes composition of the analyzed groundwater ranges from -8.8 to -6‰ vs V-SMOW for δ(18)O and from -67 to -40‰ vs V-SMOW for δ(2)H. The relatively enriched stable isotopes contents suggest the contribution of the Dahar sandstones outcrops in the current recharge of the CI aquifer in an arid context. However, the most depleted values in heavy isotopes indicate a paleorecharge of the aquifer under wetter conditions revealing a long residence time of groundwaters. The results from water samples using alpha spectrometry method indicate a range in (238)U concentrations and (234)U/(238)U activity ratios (AR) of 0.044-1.285 μg kg(-1) and 1.2 to 8.84 respectively. The geochemistry of uranium isotopes in groundwater is controlled by many factors, essentially, the influence of water rock interactions, the preferential dissolution of (234)U relative to (238)U due to alpha recoil and the mixing processes between different waters with distinct AR as well as (238)U concentrations.
Uploads
Papers by Najiba CHKIR