Contributions of Chemical and Isotopic Tools for Understanding the Groundwater Modes Recharge and Flow in the Lower Cretaceous Aquifer in the Moroccan Sahara

Nabila Edoulati, Said Boutaleb, Ismail Bettar, Ali Ouchbani

Laboratory of Applied Geosciences and Geo-Environmental, Ibn Zohr University, Agadir, Morocco.

DOI: 10.4236/jwarp.2013.52020                

Abstract

The present work was conducted in the basin of Laayoun-Dakhla (South Morocco) to: 1) identify the recharge and flow characteristics of the Lower Cretaceous aquifer (LC); and 2) provide information about the mineralization of aquifer’s water. Isotopic and hydrochemical compositions combined with the geological and hydrogeological settings were used for this purpose. The principal changes in chemical composition of LC groundwater result from mixing with water of deeper circulation. Closer analysis of available chemical data reveals the importance of dissolution/precipitation processes in evolution of groundwater chemistry. Piezometric levels, as well as chemical and isotopic composition of groundwaters, confirm hydraulic connection between the LC and the others aquifers. Overlap of some major characteristics (δ18O, δ2H, Cl^-) in this aquifer suggests that mixing processes considerably influence the hydrochemical evolution of water. The surface electrical resistivity does not indicate any freshwater-saltwater interface in the coastal aquifer and the relationship between 18O and Cl allows us to reject the hypothesis of a seawater intrusion.

Keywords

Lower Cretaceous Aquifer; Arid Area; Process of Mineralization; Seawater Intrusion; Recharge and Flow

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	R. Gonfiantini, G. Conrad, J.-Ch. Fontes, G. Sauzay and B. R. Payne, “étude Isotopique de la Nappe du Continental Intercalaire et Ses Relations Avec Les Autres Nappes du Sahara Septentrional,” Proceedings of IAEA Symposium on Isotope Techniques in Groundwater Hydrology, Vienna, 11-15 March 1974, pp. 227-241.
[2]	J. C. Fontes and R. Gonfiantini, “Isotopic Behavior during Evaporation of Two Saharan Basins,” Earth and Planetary Science Letters, Vol. 3, 1967, pp. 258-266.
[3]	Hydraulic Basin Agency, S. El Hamra and O. Ed-Dahab, “Study of the Master Plan Integrates Water Resources Mission II: Assessment of Water Needs and Potential Uses of Water Resources and Aquatic Ecosystems (Pdaire),” Repart 08/2007
[4]	A. Guendouz, A. S. Moulla, W. M. Edmunds, K. Zouar, P. Shand and A. Mamou, “Hydrogeochemical and Isotopic evolution of Water in the Complexe Terminal Aquifer in the Algerian Sahara,” Hydrogeology Journal, Vol. 11, No. 4, 2003, pp. 483-495.
[5]	S. Boutaleb, L. Bouchaou, Y. Hsissou, J. Mudry, J. Mania and P. Chauve, “Hydrogeologic Effects on the Quality of Water in the Oued Issen Watershed, Western Upper Atlas Mountains, Morocco,” Hydrogeology Journal, Vol. 8, No. 2, 2000, pp. 230-238. doi:10.1007/s100400050009
[6]	Y. Nazoumou and M. Besbes, “Estimation of Recharge and Groundwater Modeling in Arid Zone: The Case of the Sheet of Kairouan, Tunisia,” Proceedings of a Symposium Held during the Sixth IAHS Scientific Assembly, Maastricht, July 2001.
[7]	N. Al Farrah, K. Martens and K. Walraevens, “Hydro-chemistry of the Upper Miocene-Pliocene Quaternary Aquifer Complex of Jifarah Plain, NW-Libya,” Geologica Belgica, Vol. 14, No. 3-4, 2011, pp. 159-174.
[8]	A. M. Sharaky, S. A. Atta, A. S. El hassanein and K. M. A Khallaf, “Hydrogeochemistry of Groundwater in the Western Nile Delta Aquifers, Egypt,” 2nd International Conference on the Geology of Tethys, Cairo, 19-21 March 2007.
[9]	G. Choubert, “Histoire Géologique du Domaine de L’Anti Atlas,” Note et Mémoire Service Géologique Maroc, Vol. 100, 1952, pp. 75-194.
[10]	A. Michard, “Elements of Geology Morocco, Notes and Memories, Geological Survey of Morocco,” Vol. 252, 1976, pp. 1-420,
[11]	Quirol, “Regional Geology of the Moroccan Sahara,” Bureau de Recherche et de Participations Minières, 1976.
[12]	I. Davison, “Central Atlantic margin basins of North West Africa: Geology and hydrocarbon potential (Morocco to Guinea),” Journal of African Earth Sciences, 2005.
[13]	A. M. Morabet, R. Bouchta and H. Jabour, “An Overview of the Petroleum Systems of Morocco,” In: D. S. Macgregor, R. T. J. Moody and D. D. Clark-Lowes, Eds., Petroleum Geology of North Africa, Geological Society of London Special Publication, 1998, pp. 283-296.
[14]	M. A. Heyman, “Tectonic and Depositional History of the Moroccan Continental Margin,” In: A. Tankard and H. Balkwill, Eds., Extensional Tectonics and Stratigraphy of the North Atlantic Margin, AAPG Memoir 46, 1989, pp. 323-340.
[15]	L. Kouzana, “Intrusion Marine et Salinisation des Eaux D'une Nappe Phréatique Cotière (Korba, Cap-Bon, Tunisie)”, Geo-Eco-Trop, Vol. 31, 2007, pp. 57-70
[16]	A. Satriani, A. Loperte and M. Proto, “Electrical Resistivity Tomography for Coastal Salt Water Intrusion Characterization along the Ionian Coast of Basilicata Region (Southern Italy),” International Water Technology Journal, Vol. 1, No. 1, 2011.
[17]	D. Chapellier and J. L. Mari, “Cours Online de la Géo- physique de l’Université de Lausanne-Principes de Base,” 2007.
[18]	R. J. Gibbs, “Mechanisms Controlling Worlds Water Chemistry,” Science, Vol. 170, 1971, pp. 1088-1090.
[19]	S. Ettazarini, “Processes of Water-Rock Interaction in the Turonian Aquifer of Oum Er-Rabia Basin, Morocco,” Environmental Geology, Vol. 49, No. 2, 2005, pp. 293-299.
[20]	K. Srinivasamoorthy , S. Chidambaram, M. V. Prasanna, M. J. P. Vasanthavihar and P. Anandhan, “Identification of Major Sources Controlling Groundwater Chemistry from a Hard Rock Terrain: A Case Study from Mettur Taluk, Salem District, Tamil Nadu, India,” Journal of Earth System Science, Vol. 117, No. 1, 2008, pp. 49-58.
[21]	R. H. Brown, “Triassic Rocks of the Argana Valley, Southern Morocco, and Their Regional Structural Implications,” Bulletin American Association of Petroleum Geologists, Vol. 64, 1980, pp. 988-1003.
[22]	P. Le Roy and A. Pique, “Triassic-Liassic Western Moroccan synrift Basins in Relation to the Central Atlantic Opening,” Marine Geology, Vol. 172, No. 3-4, 2001, pp. 359-381. doi:10.1016/S0025-3227(00)00130-4
[23]	P. Le Roy, A. Pique, B. Le Gall, L. Ait Brahim, Al M. Morabet and A. Denati, “Coastal Basins Triassic-Liassic of Morocco and Western Intracontinental Rifting of the Diachrony of the Central Atlantic,” Bulletin de la Société Géologique de France, Vol. 168, 1997, pp. 637-648.
[24]	G. Tari, J. Molnar, P. Ashton and R. Hedley, “Salt Tectonics in the Atlantic Margin of Morocco,” The Leading Edge, Vol. 19, No. 10, 2000, pp. 1074-1078. doi:10.1190/1.1438481
[25]	G. Tari, J. Molnar, P. Ashton and R. Hedley, “Examples of Salt Tectonics from West Africa: A Comparative Approach,” In: T. Arthur, D. S. MacGregor and N. R. Cameron, Eds., Petroleum Geology of Africa: New Themes and Developing Technologies, Geological Society London Special Publications, 2003, pp. 131-150.
[26]	U. Ranke, U. Von Raad and G. Wissmann, “Stratigraphy, Facies, and Tectonic Development of On- and Offshore Aaiun-Tarfaya Basin a Review,” In: U. Von Raad, Ed., Geology of the North West African Continental Margin, Springer-Verlag, Berlin, 1982, pp. 86-104. doi:10.1007/978-3-642-68409-8_6
[27]	E. K. Uchupi, K. O. Emery, C. O. Bowin, et al., “Continental Margin off Western Africa from Senegal to Portugal,” Bulletin American Association of Petroleum Geologists, Vol. 60, 1976, pp. 809-878.
[28]	U. Von Rad and G. Wissmann, “Cretaceous-Cenozoic History of the West Saharan Continental Margin (NW Africa): Development, Destruction and Gravitational Sedimentation in Geology of NW Africa,” In: U. Von Raad, Ed., Geology of the North West African Continental Margin, Springer-Verlag, Berlin, 1982, pp. 106-129.
[29]	ONAREP, “Opportunities for Hydrocarbon Exploration and Production in Morocco,” Publicity Brochure, Morroco, 2003:
[30]	J. F. Aranyossy, “The Contribution of Isotope Techniques to Study the Recharge under Constraints Techniques and Climate Extremes,” Diploma for Accreditation to Supervise Research in Sciences, Univ. Paris- Sud (Orsay), 1991, p. 576.
[31]	J. N. Andrews, J.-Ch. Fontes, J. F. Aranyossy, A. Dodo, W. M. Edmunds, A. Joseph and Y. Travi, “The Evolution of Alkaline Groundwaters in the Continental Intercalaire Aquifer of the Irhazer Plain, Niger,” Water Resources Research, Vol. 30, No. 1, 1994, pp. 45-61. doi:10.1029/93WR02226
[32]	J. Toth, “Groundwater as a Geologic Agent: An Overview of the Causes, Processes, and Manifestations,” Hydrogeology Journal, Vol. 7, 1999, pp. 1-14.
[33]	A. El Achheb, J. Mania and J. Mudry, “Mechanisms Acquisitions Mineralization of Groundwater in the Basin-Doukkala Sahel (Western Morocco) Approach Hydro-geochemical Tracers,” Madrid, 2003.
[34]	M. Bahir, P. Carreira, M. Oliveira da Silva and P. Fernandes, “Hydrodynamical, Hydrochemical and Isotopic Characterizationc of the Kourimat Aquifer System (Essaouira basin, Morocco),” Estudios Geologicos, 2008.
[35]	S. Boutaleb, L. Bouchaou, Y. Hsissou and T. Tagma, “Determining the Terms of Recharge through Chemical and Isotopic Tracers: Case of the Contact Area Western High Atlas-Souss Plain (SW Morocco),” Estudios Geologicos, Vol. 64, No. 1, 2008.
[36]	A. Marjoua, “Origins of salts in the aquifer of the coastal Chaouia (Morocco),” Proceedings of the Rabat Symposium, April 1997.
[37]	J. F. Aranyossy, R. Njitchoua and Zuppi, “The Contribution of Environmental Isotopes to Study Recharge and Aquifer Dynamics,”In: C. Causse and F. Gasse, Eds., Hydrologie et géochimie isotopique. ORSTOM, Paris, 1998, pp. 39-54.
[38]	A. Guendouz, et al., “Hydrochemical and Isotopic Behaviour of a Saharan Phreatic Aquifer Suffering Severe Natural and Anthropic Constraints (Case of Oued-Souf Region, Algeria),” Hydrogeology Journal, Vol. 14, No. 6, 2005, pp. 955-968.
[39]	S. Kamel, L. Dassi and K. Zouari, “Approche Hydro-géologique et Hydrochimique des éChanges Hydro-dynamiques Entre Aquifères Profond et Superficiel du Bassin du Djérid, Tunisie,” Hydrological Sciences Journal, Vol. 15, No. 4, 2010, pp. 713-730.
[40]	Y. Hamed, L. Dassi, R. Ahmadi and H. Ben Dhia, “Geochemical and Isotopic Study of the Multilayer Aquifer System in the Moulares-Redayef Basin, Southern Tunisia,” Hydrological Sciences Journal, Vol. 53, No. 6, 2010.