The knowledge about groundwater flow conditions within Volta river basin in Benin, has restricted information coming to piezometry, water storage time, water path, and water quality. A good groundwater resources assessment of this sudano-sahelian area, is a huge condition for the sustainable management of water resources, which since the part of the 20th century is facing a severe drought that leads to a greater aridity. This article provides a summary with the main elements of carbon isotope ( 13 C and 14 C) as well as tritium ( 3 H) coupled with hydrogeological and hydrochemical data. The goal is to improve the initial water recharging and the groundwater flow system within the aquifer. Two main results can be produced from the groundwater chemistry. First, the interactions between groundwater and clay minerals related to the residence time of groundwater are indicated by a slight evolution of Ca-HCO 3 and Ca-Mg-HCO 3 to Na-HCO 3 . Beside that towards water types Cl-NO 3 indicates the anthropogenic influence on groundwater, related to agricultural activities and sanitation conditions. The carbon-14 activity measured on the TDIC is between 17.29 and 85.47 pmC. Therefore, it contains some samples covering a wide period of time from now to the Holocene implying a continuous system recharging over time. All the data confirm the assumption of a homogeneous, largely unified aquifer system with a multi-layer structure, but it also points out the low resource sustainability and a strong anthropogenic contamination of the most superficial horizons.
KeywordsHydrochemistryRadiocarbonRechargingResidence TimeDatingVolta River Basin in Benin
Martin, N., Eguavoen, I., Sandwidi, J.P. and Sessouma, A. (2008) Aspects hydrogéologiques et socio-légaux des eaux souterraines dans la satisfaction des besoins domestiques au niveau du bassin versant de la Volta. 13th World Water Congress, Montpellier, 1-4 September 2008, 6 p.
Banoeng-Yakubo, B., Yidana, S.M., Emmanuel, N., Akabzaa, T. and Asiedu, D. (2007) Analysis of Groundwater Quality Using Water Quality Index and Conventional Graphical Methods: The Volta Region, Ghana. Environmental Earth Sciences, 59, 867-879. https://doi.org/10.1007/s12665-009-0082-9
Boubakar Hassane, A. (2010) Aquifères superficiels et profonds et pollution urbaine en Afrique: Cas de la communauté urbaine de Niamey (NIGER). Thèse de doctorat, Université Abdou Moumouni de Niamey, Niamey, 249 p.
Totin, V.S.H., Afouda, A., Amoussou, A., Tumbulto, J. and Boko, M. (2010) Variabilité hydroclimatique et des ressources en eau de surface dans le bassin béninois de la Volta. In: Servat, E., et al., Ed., Proceedings of the Sixth World Friend Conference: Global Change: Facing Risks and Threats to Water Resources, IAHS Publication, Fez, Morocco, 164-171.
Totin, V.S.H., Zannou, A., Amoussou, E., Afouda, A. and Boko, M. (2014) Progressive Aridity Impact on the Hydrological Regime in the Volta River Basin in Benin (West Africa). Hydrology in a Changing World: Environmental and Human Dimensions. Proceedings of FRIEND-Water 2014, Montpellier, 7-10 October 2014, 17-22.
Barry, B., Obuobié, E., Andreini, M., Andah, W. and Pluquet, M. (2005) The Volta River Basin. Comprehensive Assessment of Water Management in Agriculture. Comparative Study of River Basin Development and Management. IWMI Report.
Leemhuis, C., Jung, G., Kasei, R. and Liebe, J. (2009) The Volta Basin Water Allocation System: Assessing the Impact of Small-Scale Reservoir Development on the Water Resources of the Volta Basin, West Africa. Advances in Geosciences, 21, 57-62. https://www.adv-geosci.net/21/57/2009/ https://doi.org/10.5194/adgeo-21-57-2009
Lemoalle, J. and De Condappa, D. (2009) Atlas de l’eau du bassin de la Volta. [Water Atlas of the Volta Basin.] CGIAR/CPWF, IRD, 96 p.
Ouassa-Kouaro, M. (2008) Les déterminants socioculturels de la désertification dans l’Atacora Ouest au Bénin. Thèse de doctorat, Université Paris IV et Université d’Abomey-Calavi, Cotonou, 217 p.
Idiéti, E.M. (2012) Variabilité hydro-climatique dans le bassin versant de la Pendjari (Nord-Ouest du Bénin). Thèse de Doctorat, Université d’Abomey-Calavi, Cotonou, Bénin, 229 p.
Le Barbé, L., Alé, G., Millet, B., Texier, H., Borel, Y. and Gualde, R. (1993) Les ressources en eau superficielles de la république du Bénin. Edition Orstom, Paris, France, 540 p.
Achidi, J., Bourguet, L., Elsaesser, R., Legier, A., Paulvé, E. and Tribouillard, N. (2012) Notice explicative de la carte hydrogéologique du Bénin: carte du bassin sédimentaire de la Volta à l’échelle du 1/200 000. Thechnical Report, GIZ Germany et DGEau, Cotonou, Benin, 39 p.
Vissin, E.W. (2007) Impact de la variabilité climatique et de la dynamique des états de surface sur les écoulements du bassin béninois du fleuve Niger. Thèse de Doctorat, Université de Bourgogne, Dijon, France.
Affaton, P. (1975) Etude geologique et structurale du NordOuest du Dahomey, du Nord du Togo, et du Sud-Est de la Haute Volta. Travaux Laboratoire Sciences Terre Bulletin, 10, 201.
Affaton, P., Sougy, J. and Trompette, R. (1980) The Tectono-Stratigraphic Relationships between the Upper Precambrian and Lower Paleozoic Volta Basin and the Pan-African Dahomeyide Orogenic Belt West Africa. American Journal of Science, 280, 224-248. https://doi.org/10.2475/ajs.280.3.224
Affaton, P., Aguirre, L. and Ménot, R.P. (1997) Thermal and Geodynamic Setting of the Buem Volcanic Rocks near Tiélé, Northwest Bénin, West Africa. Precambrian Research, 82, 191-209. https://doi.org/10.1016/S0301-9268(97)80686-9
Technoexport (1980) La constitution et les substances utiles de la République Populaire du Bénin entre les 10ème et 11ème parallèles de latitude nord. Rapport Office Béninois des Mines, Cotonou.
IRB Istituto Recherche Breda (1982) Etude de cartographie géologique et de prospection minière de reconnaissance au Nord du 11ème parallèle. Final Report, OBEMINES, Cotonou.
Attoh, K., Dallmeyer, R.D. and Affaton, P. (1997) Chronology of Nappe Assembly in the Pan-African Dahomeyide Orogen, West Africa: Evidence from 40Ar/39Ar Mineral Ages. Precambrian Research, 82, 153-171. https://doi.org/10.1016/S0301-9268(96)00031-9
El-Hadj Tidjani, M., Affaton, P., Louis, P. and Socohou, A. (1997) Gravity Characteristics of the Pan-African Orogen in Ghana, Togo and Benin (West Africa). Journal of African Earth Sciences, 24, 241-258. https://doi.org/10.1016/S0899-5362(97)00041-9
Ganade, C.E., Cordani, U.G., Agbossoumounde, Y., Caby, R., Basei, M.A.S., Weinberge, F.R. and Sato, K. (2016) Tightening-Up NE Brazil and NW Africa Connections: New U-Pb/Lu-Hf Zircon Data of a Complete Plate Tectonic Cycle in the Dahomey Belt of the West Gondwana Orogen in Togo and Benin. Precambrian Research, 276, 24-42. https://doi.org/10.1016/j.precamres.2016.01.032
Boukari, M. (2007) Hydrogéologie de la république du Bénin (Afrique de l’ouest). Africa Geosciences Revue, 14, 303-328.
Kalsbeek, F., Affaton, P., Ekwuemec, B., Frei, R. and Thrane, K. (2012) Geochronology of Granitoid and Metasedimentary Rocks from Togo and Benin, West Africa: Comparisons with NE Brazil. Precambrian Research, 196-197, 218-233. https://doi.org/10.1016/j.precamres.2011.12.006
Wright, J.B., Hastings, D.A., Jones, W.B. and Williams, H.R. (1985) Geology and Mineral Resources of West Africa, Vol. 187. Allen & Unwin, London.
El-Fahem, T. (2008) Hydrogeological Conceptualisation of a Tropical River Catchment in a Crystalline Basement Area and Transfer into a Numerical Groundwater Flow Model, Case Study for the Upper Ouémé Catchment in Benin. PhD Thesis, Bonn, 157 p.
Agbossoumondé, Y., Menot, R.P. and Guillot, S. (2001) Metamorphic Evolution of Neoproterozoic Eclogites from South Togo (West Africa). Journal of African Earth Sciences, 33, 227-244. https://doi.org/10.1016/S0899-5362(01)80061-0
Agbossoumondé, Y., Guillot, S. and Menot, R.P. (2004) Pan-African Subduction-Collision Event Evidenced by High-P Coronas in Metanorites from the Agou Massif (Southern Togo). Precambrian Research, 135, 1-21. https://doi.org/10.1016/j.precamres.2004.06.005
Tairou, M.S. (2006) La tectonique tangentielle panafricaine au Nord-Togo. Thèse de Doctorat, Université de Lomé 135, 401 p.
Acheampong, S.Y. and Hess, J.W. (2000) Origin of the Shallow Groundwater System in the Southern Voltaian Sedimentary Basin of Ghana: An Isotopic Approach. Journal of Hydrology, 233, 37-53. https://doi.org/10.1016/S0022-1694(00)00221-3
Prakla Seismos, Gmbh (1984) The 30 Well Drilling Project. Internal Report, Catholic Diocese of Accra, Accra, 40 p.
Acheampong, S.Y. and Hess, J.W. (1998) Hydrogeologic and Hydrochemical Framework of the Shallow Groundwater System in the Southern Voltaian Sedimentary Basin of Ghana. Hydrogeology Journal, 6, 527-537. https://doi.org/10.1007/s100400050173
Buckley, D.K. (1986) Report on Advisory Visit to Wateraid Projects in Ghana. Unpublished Report, British Geological Survey, Hydrogeology Research Group, Wallingford, 56 p.
Freeze, R.A. and Cherry, J.A. (1979) Groundwater. Prentice Hall, Englewood Cliffs.
Penna, D., Stenni, B., Wrede, S., Bogaard, T.A., Gobbi, A., Borga, M., Fischer, B.M.C., Bonazza, M. and Charova, Z. (2010) On the Reproducibility and Repeatability of Laser Absorption Spectroscopy Measurements for 2H and 18O Isotopic Analysis. Hydrology and Earth System Sciences, 7, 2975-3014. https://doi.org/10.5194/hessd-7-2975-2010
Thatcher, L.L., Janzer, V.J. and Edwards, R.W. (1977) Methods for Determination of Radioactive Substances in Water and Fluvial Sediments. In: Techniques of Water Resources Investigations, U.S. Geological Survey, Washington DC, 79-81.
Stuiver, M. and Polach, H.A. (1977) Discussion: Reporting of 14C Data. Radiocarbon, 19, 355-363.
Kortatsi, B.K., Anku, Y.S.A. and Anornu, G.K. (2009) Characterization and Appraisal of Facets Influencing Geochemistry of Groundwater in the Kulpawn Sub-Basin of the White Volta Basin, Ghana. Environmental Geology, 58, 1349-1359. https://doi.org/10.1007/s00254-008-1638-9
Adomako, D., Osae, S., Akiti, T.T., Faye, S. and Maloszewski, P. (2011) Geochemical and Isotopic Studies of Groundwater Conditions in the Densu River Basin of Ghana. Environmental Earth Sciences, 62, 1071-1084. https://doi.org/10.1007/s12665-010-0595-2
Huneau, F. and Travi, Y. (2008) The Miocene Aquifer of Valreas, France. In: Edmunds, W.M. and Shand, P., Eds., Natural Groundwater Quality, Blackwell Publishing, London, 287-305. https://doi.org/10.1002/9781444300345.ch13
Huneau, F., Dakoure, D., Celle-Jeanton, H., Vitvar, T., Ito, M., Traore, S., Compaore, N.F., Jirakova, H. and Le Coustumer, P. (2011) Flow Pattern and Residence Time of Groundwater within the South-Eastern Taoudeni Sedimentary Basin (Burkina Faso, Mali). Journal of Hydrology, 409, 423-439. https://doi.org/10.1016/j.jhydrol.2011.08.043
Dossou-Yovo, E.R., Brüggemann, N., Ampofo, E., Igue, A.M., Jesse, N., Huat, J. and Agbossou, E.K. (2016) Combining No-Tillage, Rice Straw Mulch and Nitrogen Fertilizer Application to Increase the Soil Carbon Balance of Upland Rice Field in Northern Benin. Soil & Tillage Research, 163, 152-159. https://doi.org/10.1016/j.still.2016.05.019
Lucas, L.L. and Unterweger, M.P. (2000) Comprehensible Review and Critical of the Half-Life of Tritium. Journal of Research of the National Institute of Standards and Technology, 105, 541-549.
Mook, W.G. (2001) Isotopes de l’environnement dans le cycle hydrologique. Vol, 1, 81-92.
Chéry, L. (2006) Qualité naturelle des eaux souterraines. Méthode de caractérisation des états de référence des aquifères français, Guide technique. BRGM édition, 238, 90.
Abid, K., Hadj Ammar, F., Chkir, N. and Zouari, K. (2011) Relationship between Senonian and Deep Aquifers in Southern Tunisia. Quaternary International, 257, 13-26. https://doi.org/10.1016/j.quaint.2011.09.022
Fontes, J.C., Andrews, J.N., Edmunds, W.M., Guerre, A.L. and Travi, Y. (1991) Paleorecharge by the Niger River (Mali) Deduced from Groundwater Geochemistry. Water Resources, 27, 199-214. https://doi.org/10.1029/90WR01703
Tamers, M.A. (1975) Validity of Radiocarbon Dates on Groundwater. Surveys in Geophysics, 2, 217-239. https://doi.org/10.1007/BF01447909
Fontes, J.C. and Garnier, J.M. (1979) Determination of the Initial Activity of the Total Dissolved Carbon a Review of the Existing Models and a New Approach. Water Resources Research, 12, 399-413. https://doi.org/10.1029/WR015i002p00399
Evans, G.V., Otlet, R.L., Downing, A., Monkhouse, R.A. and Rae, G. (1979) Some Problems in the Interpretation of Isotope Measurements in United Kingdom Aquifers. Isotope Hydrology II, IAEA, Vienna, 679-708.
Ingerson, E. and Pearson, F.J. (1964) Estimation of Age and Rate of Motion of Groundwater by 14C Method. In: Miyake, Y. and Koyama, T., Eds., Recent Researches in Field of Hydrosphere, Atmosphere and Nuclear Geochemistry, Maruzen, Tokyo, 263-283.
Eichinger, L. (1983) A Contribution to the Interpretation of 14C Groundwater Ages Considering the Example of a Partially Confined Sandstone Aquifer. Radiocarbon, 25, 347-356. https://doi.org/10.1017/S0033822200005634
Salem, O., Visser, J.H., Dray, M. and Gonfiantini, R. (1980) Groundwater Flow Patterns in the Western Lybian Arab Jamahiriaya. In: Arid-Zone Hydrology: Investigation with Isotope Techniques, IAEA, Vienna, 165-179.
Mook, W.G. (1980) Carbon-14 in Hydrogeological Studies. In: Fritz, P. and Fontes, J.C., Eds., Handbook of Environmental Isotopes Geochemistry 1, Elsevier, Amsterdam, 1-74. https://doi.org/10.1016/B978-0-444-41780-0.50008-0
Gasse, F. (2000) Hydrological Changes in the African Tropics since the Last Glacial Maximum. Quaternary Science Reviews, 19, 189-211. https://doi.org/10.1016/S0277-3791(99)00061-X