Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km 2 , and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm 3 /year, and in 2015 about 2.91 Mm 3 /year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.
KeywordsFum Al Wad AquiferOver-ExploitationPumping WellsSaltwater IntrusionPiezometric HeadWater-Table
Gaaloul, N. (2011) Water Resources and Management in Tunisia. International Journal of Water, 6, 92-116.
Bear, J., Cheng, A.H.D., Sorek, S., Herrera, I. and Ouazar, D. (1999) Seawater Intrusion in Coastal Aquifers. Kluwer Academic Publishers, Dordrecht, 625 p.
Chatelier, N.C. and Surdyk, N. (2011) Sea Level Rise Induced by Climate Change: Consequences on Saline Intrusion in the Coastal Aquifers of Metropolitan France. BRGM Report.
Comte, J.C. (2008) Contribution of Electrical Tomography to the Modeling of Densities in Coastal Aquifers. PhD Thesis, University of Avignon and Pays de Vaucluse, Avignon.
Priyanka, B.N. and Mohan Kumar, M.S. (2017) Direct and Inverse Modeling of Seawater Intrusion: A Perspective. Journal Geological Society of India, 90, 595-601. https://doi.org/10.1007/s12594-017-0757-x
Colombani, N. and Mastrocicco, M. (2017) Modelling the Salinization of a Coastal Lagoon-Aquifer System. IOP Conference Series Earth and Environmental Science, 82, Article ID: 012003. https://doi.org/10.1088/1755-1315/82/1/012003
Gopinath, S., Srinivasamoorthy, S., Saravanan, K., Suma, K., Prakash, C.S., Senthilnathan, R., Chandrasekaran, D., Srinivas, N., Sriniva, Y. and Sarma, V.S. (2016) Modeling Saline Water Intrusion in Nagapattinam Coastal Aquifers, Tamilnadu, India. Modeling Earth Systems and Environment, 2, 2. https://www.researchgate.net/publication/286477701
Lathashri, U.A. and Mahesha, A. (2015) Simulation of Saltwater Intrusion in a Coastal Aquifer in Karnataka, India. International Conference on Water Resources, Coastal and Ocean Engineering, Mangalore, 12-14 March 2015, 700-705. http://creativecommons.org/licenses/by-nc-nd/4.0/
Zexuan, X., Bill, X.H. and Ming, Y. (2017) Numerical Modeling and Sensitivity Analysis of Seawater Intrusion in a Dual-Permeability Coastal Karst Aquifer with Conduit Networks. Hydrology and Earth System Sciences, 22, 221-239, https://doi.org/10.5194/hess-2017-85
Idris, A.N., Aris, A.Z., Narany, T.S., Mangala, S.P., Suratman, S., Tawnie, I., Shamsuddin, M.K.N. and Sefie, A. (2017) Simulation of Saltwater Intrusion in Coastal Aquifer of Kg. Salang, Tioman Island, Pahang, Malaysia. MATEC Web of Conferences, 103, Article No. 04024. https://doi.org/10.1051/matecconf/201710304024
Thomas, A., Eldho, T.I. and Rastogi, A.K. (2016) Simulation of Seawater Intrusion in Coastal Confined Aquifer Using a Point Collocation Method Based Meshfree Model. Journal of Water Resource and Protection, 8, 534-549. http://www.scirp.org/journal/jwarp https://doi.org/10.4236/jwarp.2016.84045
Noorabadi, S., Sadraddini, A.A., Nazemi, A.H. and Delirhasannia, R. (2017) Laboratory and Numerical Investigation of Saltwater Intrusion into Aquifers. Journal of Materials and Environmental Sciences, 8, 4273-4283. http://www.jmaterenvironsci.com/
Hanasaki, N., Yoshikawa, S., Kakinuma, K. and Kanae, S. (2016) A Seawater Desalination Scheme for Global Hydrological Models. Hydrology and Earth System Sciences, 20, 4143-4157. http://www.hydrol-earth-syst-sci.net/20/4143/2016/ https://doi.org/10.5194/hess-20-4143-2016
Frissant, N., René-Crail, C., Bonnier, J. and De La Torre, Y. (2005) The Phenomenon of Saline Intrusion in Réunion: State of Knowledge and Synthesis of Available Data. Report BRGM/RP-54330-FR.
Christian, D., Langevin1, W., Shoemaker1, B. and Weixing, G. (2003) MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model-Documentation of the SEAWAT-2000 Version with the Variable-Density Flow Process (VDF) and the Integrated MT3DMS Transport Process (IMT). U.S. Geological Survey Open-File Report 03-426.
Arfib, B., Cavalera, T. and Gilli, E. (2006) Influence of Hydrodynamics on the Saltwater Intrusion in Coastal Karstic Aquifer. C. R. Geoscience, 338, 757-767. https://doi.org/10.1016/j.crte.2006.07.001
Bear, J. (1979) Hydraulics of Groundwater. Mac Graw-Hill, Inc., New York, 568 p.
Barlow Paul, M. (2003) Ground Water in Freshwater-Saltwater Environments of the Atlantic Coast.
ABHSHOD (Hydraulic Basin Agency of the Sakia El Hamra and Wadi Eddahab) (2010) Inventory of the Pumping Groundwater in the Basin of Sakia El Hamra and Wad Eddahab.
DRHS (Regional Direction of Sahara Hydraulic) (2003) Geophysical Survey by Electrical Soundings, by Nuclear Magnetic Resonance Soundings and by Seismic in the Laayoun-Dakhla Sedimentary Basin.
Dillon, R. and Soujy, J. (1974) Geology of West Africa and Canary and Cape Verde Islands. In: Nairn, A.E.M. and Stehli, F.G., Eds., The Ocean Basins and Margin, Volume 2: The North Atlantic, Plenum Press, New York, 315-390. https://doi.org/10.1007/978-1-4684-3033-2_10
Lehner, P. and De Ruiter, P.A.D. (1977) Structural History of the Atlantic Margin of Africa. Bulletin—American Association of Petroleum Geologists, 61, 961-981.
Alia, M. (1945) Caracteristicas morphograficas y geologicas de la zona septentrional del sahara espanol.
Alia, M. (1945) El Quaternario en el Sahara espanol. 149-163.
Choubert, G. and Ambroggi, R. (1953) Preliminary Note on the Presence of Two Sedimentary Cycles in the Marine Pliocene of Morocco. Notes Serv. Geol. Morocco, t. 7Mem., No. 117, 5-53.
Choubert, G., Faure Muret, A. and Hottinger, L. (1966) Geological Survey of the Coastal Basin of Tarfaya. Notes et memoires du service geologique No 175 Tome I, stratigraphie, 7-106.
Lecointre, G. (1952) Research on the Neogene and the Quaternary Marine of the Atlantic Coast of Morocco. Notes and Mem. Serv. Geol. Morocco, No. 174, t. III.
Lecointre, G. (1963) Note on the Marine Neogene and Quaternary of the Spanish Sahara (Seguia el Hamra and Rio the Oro). Notas Com. Inst. geol. minero Esp., No. 71.
Lecointre, G. (1965) A Hypothesis on the Age of Quaternary Transgression in Mauritania. Notes and Mem. Serv. Geol. Morocco., t. 25, No. 185, 79-80.
Lecointre, G. (1966) Neogene and Quaternary of the Tarfaya Coastal Basin. Notes and Mem. Serv. Geol. Morocco., No. 175, 255-288.
Martinis, B. and Visintin, V. (1966) Geological Datas on the Coastal Sedimentary Basin of Tarfaya (Southern Morocco). In: Reyre, D., Ed., Sedimentary Basins of the African Coast, Part 1 (Atlantic Coast), Ass Afr Geol Surv, UNESCO, 13-26.
Ratschiller, L.K. (1970) Lithostratigraphy of the Northern Spanisch Sahara. Mem. Mus. Trid. Sc. Nat trento, Vol. 18, fasc. 1, 9-78.
MEM (Ministry of Energy and Mines) (2002) Geological Map to 1000000th. Paper of Laayoun.
Harbaugh, A.W., Banta, E.R., Hill, M.C. and McDonald, M.G. (2000) MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model-User Guide to Modularization Concepts and the Ground-Water Flow Process. U.S. Geological Survey Open-File Report 00-92, 121 p.
Zheng, C. (2006) MT3DMS v5.2 Supplemental User’s Guide. Technical Report to the U.S. Army Engineer Research and Development Center, Department of Geological Sciences, University of Alabama, Tuscaloosa, 24 p.
Zheng, C. and Wang, P.P. (1999) MT3DMS, A Modular Three-Dimensional Multi-Species Transport Model for Simulation of Advection, Dispersion and Chemical Reactions of Contaminants in Groundwater Systems; Documentation and User’s Guide. U.S. Army Engineer Research and Development Center Contract. Report SERDP-99-1, Vicksburg, 202 p.
Guo, W. and Langevin, C.D. (2002) User’s Guide to SEAWAT: A Computer Program for Simulation of Three-Dimensional Variable-Density Ground-Water Flow: U.S. Geological Survey Techniques of Water-Resources Investigations. Book 6, Chap. A7, 77 p.
Bear, J. and Bachmat, Y. (1991) Introduction to Modeling of Transport Pheno-Mena in Porous Media. Kluwer Academic Publishers, Dordrecht.
DRHS (Regional Direction of Sahara Hydraulic) (2005) Modeling Study of the Fum Al Wad Aquifer-Laayoun Region, Morocco.
El Mokhtar, M., Chibout, M., El Kanti, S.M., El Mansouri, B., Benslimane, A. and Faqihi, F.-Z. (2016) Application of Geophysical Methods to the Determination of the Hydrogeological Situation of the Saline Intrusion at the Sensing Field of the Fum Al Wad Coastal Aquifer, Province of Laayoun, Morocco. Journal of Geomaghreb, 12, 1-11.