Contribution of Piezometry and Hydro-Geochemistry to a Better Understanding of the Adamawa-Yadé Hard Rock Aquifer System in Ngaoundéré

Tamonkem Adzeh Roger^1, , Kemgang Dongmo Tchouta¹, Mvondo Valentin Yvan Emmanuel², Iwoudam Maïvow Edmond¹ and Ngounou Ngatcha Benjamin¹

¹The University of Ngaoundéré - Faculty of Science - Department of Earth Sciences - P.O. Box 454 Ngaoundéré

²Agricultural Research Centre of Maroua, P.O. Box 33 Maroua

Cite this paper

Tamonkem Adzeh Roger, Kemgang Dongmo Tchouta, Mvondo Valentin Yvan Emmanuel, Iwoudam Maïvow Edmond and Ngounou Ngatcha Benjamin. Contribution of Piezometry and Hydro-Geochemistry to a Better Understanding of the Adamawa-Yadé Hard Rock Aquifer System in Ngaoundéré. American Journal of Water Resources. 2024; 12(2):39-52. doi: 10.12691/AJWR-12-2-2

Abstract

The hard rock-aquifer system in the urban context of Ngaoundere was investigated using piezometric measurements and hydro-chemistry to enhance understanding of its functioning and assess groundwater suitability for drinking and domestic purposes. Seasonal and intra-seasonal piezometric monitoring was conducted in different localities, along with chemical analysis of thirty-five ground and surface water samples. The chemical composition was determined for major elements was determined using ion chromatography, and water facies and mineralization processes were assessed using Piper and Gibbs diagrams. The water quality index (WQI) was calculated to evaluate groundwater suitability for human consumption. The findings revealed diverse piezometric behaviors depending on well/borehole geomorphological positions and seasons. Wells situated on hilltops exhibited high piezometric fluctuations, while those in valleys near rivers showed low fluctuations due to support from river water levels. Recharge occurred during the rainy season through direct infiltration from hilltops, with stream water levels influencing piezometric levels in surrounding wells and boreholes. The surface and ground waters exhibited low mineralization, characterized by calcium-magnesium bicarbonate and sodic-potassic bicarbonate facies. Water-rock interactions and dilution with rainwater were identified as the main processes controlling water mineralization. According to the WQI, all groundwater samples were classified as "excellent quality water" for human consumption. However, the microbiological quality of groundwater in and around Ngaoundere was influenced by human activities, making it unsuitable for drinking without treatment.

Keywords

hard-rock aquifer, hydrodynamic, water-mineralization, water-quality, Ngaoundere

Copyright

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References

[1]	Soro, G.; Soro, N.; Ahoussi, K.E.; Lasm, T.; Kouame, F.K.; Soro, T.D.; Biemi, J. Assessment of the Hydraulic Properties of Fractured Aquifers in Crystalline and Metamorphic Formations in the Region of Lacs (Central Cote d’Ivoire). Estud. Geol. Madr. 2010, 66, 227–242.
[2]	Carter, R.C.; Parker, A. Climate Change, Population Trends and Groundwater in Africa. 2009.
[3]	Foster, S.; Chilton, J.; Moench, M.; Cardy, F.; Schiffler, M. Groundwater in Rural Development: Facing the Challenges of Supply and Resource Sustainability. World Bank Tech. Pap. 2000.
[4]	Kouam Kenmogne, G.; Rosillon, F.; Mpakam, H.; Nono, A. Enjeux sanitaires, socio-économiques et environnementaux liés à la réutilisation des eaux usées dans le maraîchage urbain : cas du bassin versant de l’Abiergué (Yaoundé-Cameroun). VertigO Rev. Électronique En Sci. L’environnement 2010, 10, 0–0.
[5]	La Banque Africaine de Developpement; Bankgroup The Africa Water Vision for 2025: Equitable and Sustainable Use of Water for Socioeconomic Development. Econ. Comm. Afr. Addis Abeba Ethiop. 2000.
[6]	Macdonald, A.M.; Calow, R.C.; Macdonald, D.M.J.; Darling, W.G.; Dochartaigh, B.É.Ó. What Impact Will Climate Change Have on Rural Groundwater Supplies in Africa? Hydrol. Sci. J. 2009, 54, 690–703.
[7]	Macdonald, A.; Bonsor, H.; Ó Dochartaigh, B.; Taylor, R. Quantitative Maps of Groundwater Resources in Africa. Environ. Res. Lett. 2012, 7, 024009.
[8]	Nono, A.; Likeng, J.; Wabo, H.; Tabue Youmbi, G.; Biaya, S. Influence de La Nature Lithologique et Des Structures Géologiques Sur La Qualité et La Dynamique Des Eaux Souterraines Dans Les Hauts Plateaux de l’Ouest-Cameroun. Int. J. Biol. Chem. Sci. 2009, 3.
[9]	WHO Progress on Drinking Water and Sanitation: Special Focus on Sanitation; World Health Organization, 2008;
[10]	Ngounou Ngatcha, B. Hydrogéologie d’aquifères Complexes En Zone Semi-Aride : Les Aquifères Quaternaires Du Grand Yaéré (Nord Cameroun). These de doctorat, Université Joseph Fourier (Grenoble ; 1971-2015), 1993.
[11]	Wakode, H.B.; Baier, K.; Jha, R.; Ahmed, S.; Azzam, R. Assessment of Impact of Urbanization on Groundwater Resources Using GIS Techniques-Case Study of Hyderabad, India. Int. J. Environ. Res. 2014, 8, 1145–1158.
[12]	Wakode, H.B.; Baier, K.; Jha, R.; Azzam, R. Impact of Urbanization on Groundwater Recharge and Urban Water Balance for the City of Hyderabad, India. Int. Soil Water Conserv. Res. 2018, 6, 51–62.
[13]	Acworth, R.I. The Development of Crystalline Basement Aquifers in a Tropical Environment. Q. J. Eng. Geol. 1987, 20, 265–272.
[14]	Lachassagne, P.; Wyns, R. Aquifères de Socle: Nouveaux Concepts. Application à La Prospection et La Gestion de La Ressource En Eau. Géosciences 2005, 32–37.
[15]	Razack, M.; Lasm, T. Geostatistical Estimation of the Transmissivity in a Highly Fractured Metamorphic and Crystalline Aquifer (Man-Danane Region, Western Ivory Coast). J. Hydrol. 2006, 325, 164–178.
[16]	Jones, M.J. The Weathered Zone Aquifers of the Basement Complex Areas of Africa. Q. J. Eng. Geol. 1985, 18, 35–46.
[17]	Lachassagne, P.; Dewandel, B.; Wyns, R. Review: Hydrogeology of Weathered Crystalline/Hard-Rock Aquifers—Guidelines for the Operational Survey and Management of Their Groundwater Resources. Hydrogeol. J. 2021, 29, 2561–2594.
[18]	Lachassagne, P.; Wyns, R.; Dewandel, B. The Fracture Permeability of Hard Rock Aquifers Is Due Neither to Tectonics, nor to Unloading, but to Weathering Processes. Terra Nova 2011, 23, 145–161.
[19]	Wyns, R.; Gourry, J.C.; Baltassat, J.M.; Lebert, F. Caractérisation Multiparamètres Des Horizons de Subsurface (0–100 m) En Contexte de Socle Altéré. In Proceedings of the 2e Colloque GEOFCAN, BRGM, IRD, UPMC; 1999; pp. 105–110.
[20]	Tchapnga, H.B.D.; Ngnikam, E.; Tanawa, E. Approvisionnement En Eau Potable; Presses Universitaires de Yaoundé, 2001;
[21]	Singhal, B.B.S.; Gupta, R.P. Water-Wells. In Applied Hydrogeology of Fractured Rocks: Second Edition; Singhal, B.B.S., Gupta, R.P., Eds.; Springer Netherlands: Dordrecht, 2010; pp. 299–315 ISBN 978-90-481-8799-7.
[22]	Bon, A.F.; Ndam Ngoupayou, J.R.; Ewodo Mboudou, G.; Ekodeck, G.E. Caractérisation Hydrogéologique Des Aquifères de Socle Altéré et Fissuré Du Bassin Versant de l’Olézoa à Yaoundé, Cameroun. Rev. Sci. L’eau 2016, 29, 149–166.
[23]	Bon, A.F.; Ngo Ngoss, T.A.M.; Ewodo Mboudou, G.; Banakeng, L.A.; Ndam Ngoupayou, J.R.; Ekodeck, G.E. Groundwater Flow Patterns, Hydrogeochemistry and Metals Background Levels of Shallow Hard Rock Aquifer in a Humid Tropical Urban Area in Sub-Saharan Africa-A Case Study from Olézoa Watershed (Yaoundé-Cameroon). J. Hydrol. Reg. Stud. 2021, 37, 100904.
[24]	Gastmans, D.; Hutcheon, I.; Menegário, A.A.; Chang, H.K. Geochemical Evolution of Groundwater in a Basaltic Aquifer Based on Chemical and Stable Isotopic Data: Case Study from the Northeastern Portion of Serra Geral Aquifer, São Paulo State (Brazil). J. Hydrol. 2016, 535, 598–611.
[25]	Malomo, S.; Okufarasin, V.A.; Olorunniwo, M.A.; Omode, A.A. Groundwater Chemistry of Weathered Zone Aquifers of an Area Underlain by Basement Complex Rocks. J. Afr. Earth Sci. Middle East 1990, 11, 357–371.
[26]	Njueya, A.K.; Zebaze, A.T.; Kengni, L.; Temgoua, E.; Nkouathio, D.G.; Chezie, S.D. Assessment of Groundwater Mineralization Processes in Mbakaou Area (Adamawa Plateau – Cameroon), by Using Conventional Diagrams and Multivariate Statistical Analysis. Eur. J. Environ. Earth Sci. 2021, 2, 44–52.
[27]	Njueya, A.K.; Kengni, L.; Fonteh, M.F.; David Nkouathio, G.; Mebo, S.M.B. Characterization of Aquifers and Hydrogeochemical Processes in Ngaoundéré, Adamawa Region, Cameroon. Arab. J. Geosci. 2022, 15, 1024.
[28]	Sonkamble, S.; Sahya, A.; Mondal, N.C.; Harikumar, P. Appraisal and Evolution of Hydrochemical Processes from Proximity Basalt and Granite Areas of Deccan Volcanic Province (DVP) in India. J. Hydrol. 2012, 438–439, 181–193.
[29]	Khatri, N.; Tyagi, S. Influences of Natural and Anthropogenic Factors on Surface and Groundwater Quality in Rural and Urban Areas. Front. Life Sci. 2015, 8, 23–39.
[30]	Ngatcha, B.N.; Mudry, J.; Aranyossy, J.F.; Naah, E.; Reynault, J.S. Apport de La Géologie, de l’hydrogéologie et Des Isotopes de l’environnement à La Connaissance Des «nappes En Creux» Du Grand Yaéré (Nord Cameroun). Rev. Sci. EauJournal Water Sci. 2007, 20, 29–43.
[31]	Yan, Z.-W.; Wang, J.; Xia, J.-J.; Feng, J.-M. Review of Recent Studies of the Climatic Effects of Urbanization in China. Adv. Clim. Change Res. 2016, 7, 154–168.
[32]	Ganwa, A.A.; Frisch, W.; Siebel, W.; Shang, C.K.; Mvondo Ondoa, J.; Satir, M.; Tchakounté Numbem, J. Zircon 207Pb/206Pb Evaporation Ages of Panafrican Metasedimentary Rocks in the Kombé-II Area (Bafia Group, Cameroon): Constraints on Protolith Age and Provenance. J. Afr. Earth Sci. 2008, 51, 77–88.
[33]	Ganwa, A.A.; Klötzli, U.S.; Hauzenberger, C. Evidence for Archean Inheritance in the Pre-Panafrican Crust of Central Cameroon: Insight from Zircon Internal Structure and LA-MC-ICP-MS Usbnd Pb Ages. J. Afr. Earth Sci. 2016, 120, 12–22.
[34]	Nzenti, J.P.; Barbey, P.; Bertrand, J.M.; Macaudière, J. La Chaîne Panafricaine Au Cameroun: Cherchons Suture et Modèle. Abstr. 15eme RST Nancy Société Géologique Fr. Édition Paris 1994, 99.
[35]	Penaye, J.; Toteu, S.F.; Michard, A.; Bertrand, J.-M.; Dautel, D. Reliques Granulitiques d’âge Protérozoïque Inférieur Dans La Zone Mobile Panafricaine d’Afrique Centrale Au Cameroun; Géochronologie U-Pb Sur Zircons. CR Acad Sci Paris 1989, 309, 315–318.
[36]	Saha-Fouotsa, A.N.; Tchameni, R.; Vanderhaeghe, O.; Zeh, A.; Tchunte, P.M.F.; Eglinger, A.; Nomo, E.N.; Barbey, P. Lu-Hf Isotopic Data of the Mbé-Sassa-Mbersi Tonalite (Central Cameroon Domain): Indicator of ca. 1.0 Ga Juvenile Tonian Magmatism in the Region. J. Geosci. Environ. Prot. 2021, 9, 1–19.
[37]	Tchameni; Pouclet, A.; Penaye, J.; Ganwa, A.A.; Toteu, S.F. Petrography and Geochemistry of the Ngaoundéré Pan-African Granitoids in Central North Cameroon: Implications for Their Sources and Geological Setting. J. Afr. Earth Sci. 2006, 44, 511–529.
[38]	Tchouatcha, M.S.; Kouske, A.P.; Galal, W.F.; Mahmoud, M.S.; Sobdjou, C.K.; Ngantchu, L.D.; Takou, J.P.; Preat, A.; Noubissie, C.G.; Miyemeck Ngonlep, V.T. The Cretaceous of the Cameroon Atlantic Basin (Central Africa): Sediment Provenance, Correlation, Paleoenvironment and Paleogeographic Evolution of the Eastern Proto-Atlantic Margin (Central Gondwana). Environ. Earth Sci. 2023, 82, 103.
[39]	Nguetnkam, J.P.; Solleiro-Rebolledo, E.; Díaz-Ortega, J.; Tématio, P. Evaluating Weathering of Palaeosols in Cameroon (Central Africa) as a Tool for Paleoenvironmental Reconstruction. CATENA 2020, 194, 104688.
[40]	Sighomnou, D. Analyse et Redéfinition Des Régimes Climatiques et Hydrologiques Du Cameroun: Perspectives d’évolution Des Ressources En Eau. These Doct Etat Univ Yaoundé Cameroun 2004.
[41]	Suchel, J.B. Les Régions Climatiques Du Cameroun. Clim. Cameroun Thčse Dr. D‟ Etat Univ. St Etienne Fr. 1988.
[42]	Djoufack, V. Étude multi-échelles des précipitations et du couvert végétal au Cameroun : Analyses spatiales, tendances temporelles, facteurs climatiques et anthropiques de variabilité du NDVI. PhD Thesis, Université de Bourgogne, 2011.
[43]	Vicat, J.-P.; Ngounouno, I.; Pouclet, A. Existence de Dykes Doléritiques Anciens à Composition de Tholéiites Continentales Au Sein de La Province Alcaline de La Ligne Du Cameroun. Implication Sur Le Contexte Géodynamique. Comptes Rendus Académie Sci. - Ser. IIA - Earth Planet. Sci. 2001, 332, 243–249.
[44]	Dawaï, D.; Tchameni, R.; Bascou, J.; Wangmene, S.A.; Tchunte, P.M.F.; Bouchez, J.-L. Microstructures and Magnetic Fabrics of the Ngaoundéré Granite Pluton (Cameroon): Implications to the Late-Pan-African Evolution of Central Cameroon Shear Zone. J. Afr. Earth Sci. 2017, 129, 887–897.
[45]	Toteu, S.F.; Penaye, J.; Djomani, Y.P. Geodynamic Evolution of the Pan-African Belt in Central Africa with Special Reference to Cameroon. Can. J. Earth Sci. 2004, 41, 73–85.
[46]	Nkouandou, O.F.; Ngounouno, I.; Déruelle, B.; Ohnenstetter, D.; Montigny, R.; Demaiffe, D. Petrology of the Mio-Pliocene Volcanism to the North and East of Ngaoundéré (Adamawa, Cameroon). Comptes Rendus Géoscience 2008, 340, 28–37.
[47]	Nkouandou, O.F.; Bardintzeff, J.-M.; Fagny, A.M. Sub-Continental Lithospheric Mantle Structure beneath the Adamawa Plateau Inferred from the Petrology of Ultramafic Xenoliths from Ngaoundéré (Adamawa Plateau, Cameroon, Central Africa). J. Afr. Earth Sci. 2015, 111, 26–40.
[48]	Fagny, A.M.; Nkouandou, O.F.; Bardintzeff, J.-M.; Temdjim, R.; Guillou, H. Pétrologie Du Volcanisme Eocène-Oligocène Du Massif de Tchabal Mbabo, Adamaoua-Cameroun, Afrique Centrale. Afr. Sci 2016, 12, 35–47.
[49]	Ganwa, A.A.; Siebel, W.; Frisch, W.; Shang, C.K. Geochemistry of Magmatic Rocks and Time Constraints on Deformational Phases and Shear Zone Slip in the Méiganga Area, Central Cameroon. Int. Geol. Rev. 2011, 53, 759–784.
[50]	Bitom, D. Organisation et Évolution d’une Couverture Ferralitique En Zone Tropicale Humide (Cameroun): Génèse et Transformation d’ensembles Ferrugineux Indurés Profonds. PhD Thesis, Poitiers, 1988.
[51]	Mathieu, C. Les Principaux Sols Du Monde: Voyage à Travers l’épiderme Vivant de La Planète Terre; Ed. Tec & Doc, 2009;
[52]	Souaibou, S.; Ondoa, J.M.; Elimbi, A.; Ekodeck, G.E.; Kamgang, V.K.B. Caractéristiques Morphologiques et Géochimiques Des Manteaux d’altération Développés Sur Granitoïdes Dans La Région de l’Adamaoua (Cameroun). Eur. Sci. J. 2015, 11.
[53]	Tchaptchet, T.W.; Tematio, P.; Guimapi, T.N.; Happi, E.; Tiomo, I.; Momo, N.M. Morphological, Mineral and Geochemical Characterization of Soil Profiles in Meïganga as Tools for Rock Weathering Intensity and Trend Evaluation and Residual Ore Deposit Prospection in the Mineralized Domain of Central Cameroon. 2020.
[54]	Lachassagne, P.; Aunay, B.; Frissant, N.; Guilbert, M.; Malard, A. High-Resolution Conceptual Hydrogeological Model of Complex Basaltic Volcanic Islands: A Mayotte, Comoros, Case Study. Terra Nova 2014, 15.
[55]	Lachassagne, P.; Dewandel, B.; Wyns, R. The Conceptual Model of Hard Rock Aquifers and Its Practical Applications. Vingtièmes Journ. Tech. Com. Fr. Hydrogéologie Assoc. Int. Hydrogéologues Roche-Sur-Yon 11 Pp 2015.
[56]	Zebaze, A.T.; Njueya, A.K.; Kwekam, M.; Temgoua, E. Assessment of Hydrogeoelectrical Characteristics of Crystalline Aquifers and Groundwaters Quality in Adamawa Plateau: Case of Mbakaou (Adamawa-Cameroon). Environ. Earth Sci. Res. J. 2020, 7.
[57]	Ngounou Ngatcha, B.; Sara, L.; Ekodeck, G. Problématique de L’Accès à L’Eau Potable Dans La Ville de Ngaoundéré (Centre Nord-Cameroun). Editor. Advis. Board E 2007, 18, 223–230.
[58]	Courtois, N. Ressources En Eaux Souterraines En Zone de Socle de La Vendée–Aspects Qualitatifs. Rapp. BRGM N RP-50394-FR 2000.
[59]	Piper, A. A Graphic Procedure in the Geochemical Interpretation of Water Analyses. Am. Geophys. Union Trans. 1944, 25, 914–923.
[60]	Singh, D.F. Studies on the Water Quality Index of Some Major Rivers of Pune, Maharashtra. In Proceedings of the Proc Acad Environ Biol; 1992; Vol. 1, pp. 61–66.
[61]	Raghunathan, T.S.; Subba Rao, S.; Solis, L.E. A Comparative Study of Quality Practices: USA, China and India. Ind. Manag. Data Syst. 1997, 97, 192–200.
[62]	Mishra, P.C.; Patel, R.K. Quality of Drinking Water in Rourkela, Outside the Steel Township. J. Environ. Pollut. 2001, 8, 165–169.
[63]	Varol, S.; Davraz, A. Evaluation of the Groundwater Quality with WQI (Water Quality Index) and Multivariate Analysis: A Case Study of the Tefenni Plain (Burdur/Turkey). Environ. Earth Sci. 2015, 73, 1725–1744.
[64]	WHO Guidelines for Drinking-Water Quality: First Addendum to the Fourth Edition. In Guidelines for drinking-water quality: first addendum to the fourth edition; 2017.
[65]	Sahu, P.; Sikdar, P.K. Hydrochemical Framework of the Aquifer in and around East Kolkata Wetlands, West Bengal, India. Env. Geol 2008, 55, 823–835.
[66]	Edmunds, W.M.; Fellman, E.; Goni, I.B. Lakes, Groundwater and Palaeohydrology in the Sahel of NE Nigeria: Evidence from Hydrogeochemistry. J. Geol. Soc. 1999, 156, 345–355.
[67]	Kuitcha, D.; Takounjou, A.L.F.; Ndjama, J. Apport de l’hydrochimie et de l’isotope de l’environnement à La Connaissance Des Ressources En Eaux Souterraines de Yaoundé, Cameroun. J. Appl. Biosci. 2013, 67, 5194–5208.
[68]	Lapworth, D.J.; MacDonald, A.M.; Tijani, M.N.; Darling, W.G.; Gooddy, D.C.; Bonsor, H.C.; Araguás-Araguás, L.J. Residence Times of Shallow Groundwater in West Africa: Implications for Hydrogeology and Resilience to Future Changes in Climate. Hydrogeol. J. 2012, 21, 673–686.
[69]	Ngoupayou, J.R.N.; Bon, A.F.; Mboudou, G.E.; Abdou, N.N.; Ekodeck, G.E. Hydrogeological Characteristics of Shallow Hard Rock Aquifers in Yaounde (Cameroon, Central Africa). In Groundwater Hydrology; IntechOpen, 2019.
[70]	70. Takounjou, A.F.; Ngoupayou, J.N.; Riotte, J.; Takem, G.E.; Mafany, G.; Maréchal, J.C.; Ekodeck, G.E. Estimation of Groundwater Recharge of Shallow Aquifer on Humid Environment in Yaounde, Cameroon Using Hybrid Water-Fluctuation and Hydrochemistry Methods. Environ. Earth Sci. 2010, 64, 107–118.
[71]	Chilton, P.J.; Foster, S.S.D. Hydrogeological Characterisation And Water-Supply Potential Of Basement Aquifers In Tropical Africa. Hydrogeol. J. 1995, 3, 36–49.
[72]	Compaore, G.; Lachassagne, P.; Travi, Y. Evaluation Du Stock d’eau Des Altérites: Expérimentation Sur Le Site Granitique de Sanon (Burkina Faso). IAHS-AISH Publ. 1997, 241.
[73]	Nkouandou, O.F.; Ngounouno, I.; Deruelle, B. Géochimie Des Laves Basaltiques Récentes Des Zones Nord et Est de Ngaoundéré (Cameroun, Plateau de l’Adamaoua, Afrique Centrale): Pétrogenèse et Nature de La Source. Int. J. Biol. Chem. Sci. 2010, 4.
[74]	Nguet, P.W.; Ntieche, B.; Tchop, J.L.; Mana, B.C.; Mbossi, E.F. Geochemistry of Volcanic Rocks of Beka, North East of Ngaoundéré (Adamawa Plateau, Cameroon): Petrogenesis and Geodynamic Context. J. Geol. Res. 2021, 3.
[75]	Ganwa, A.A.; Siebel, W.; Frisch, W.; Shang, C.K. Geochemistry of Magmatic Rocks and Time Constraints on Deformational Phases and Shear Zone Slip in the Méiganga Area, Central Cameroon. Int. Geol. Rev. 2011, 53, 759–784.
[76]	Dewandel, B.; Lachassagne, P.; Zaidi, F.K.; Chandra, S. A Conceptual Hydrodynamic Model of a Geological Discontinuity in Hard Rock Aquifers: Example of a Quartz Reef in Granitic Terrain in South India. J. Hydrol. Amst. 2011, 405, 474–487.
[77]	Guihéneuf, N.; Boisson, A.; Bour, O.; Dewandel, B.; Perrin, J.; Dausse, A.; Viossanges, M.; Chandra, S.; Ahmed, S.; Maréchal, J.C. Groundwater Flows in Weathered Crystalline Rocks: Impact of Piezometric Variations and Depth-Dependent Fracture Connectivity. J. Hydrol. 2014, 511, 320–334.
[78]	Santoni, S.; Huneau, F.; Garel, E.; Aquilina, L.; Vergnaud-Ayraud, V.; Labasque, T.; Celle-Jeanton, H. Strontium Isotopes as Tracers of Water-Rocks Interactions, Mixing Processes and Residence Time Indicator of Groundwater within the Granite-Carbonate Coastal Aquifer of Bonifacio (Corsica, France). Sci. Total Environ. 2016, 573, 233–246.
[79]	Chegbeleh, L.P.; Akurugu, B.; Yidana, S. Assessment of Groundwater Quality in the Talensi District, Northern Ghana. Sci. World J. 2020, 2020, 1–24.
[80]	Aboubacar Modibo, S.; Lin, X.; Koné, S. Assessing Groundwater Mineralization Process, Quality, and Isotopic Recharge Origin in the Sahel Region in Africa. Water 2019, 11, 789.
[81]	Sunkari, E.; Abu, M.; Bayowobie .S, P.; Dokuz, U. Hydrogeochemical Appraisal of Groundwater Quality in the Ga West Municipality, Ghana: Implication for Domestic and Irrigation Purposes. Groundw. Sustain. Dev. 2019, 8, 501–511.
[82]	Aquilina, L.; Stumpp, C.; Tonina, D.; Buffington, J.M. Hydrodynamics and Geomorphology of Groundwater Environments. In Groundwater Ecology and Evolution; Elsevier, 2023; pp. 3–37.
[83]	Bouteldjaoui, F.; Bessenasse, M.; Kettab, A.; Scheytt, T. Combining Geology, Hydrogeology and Groundwater Flow for the Assessment of Groundwater in the Zahrez Basin, Algeria. Arab. J. Geosci. 2019, 12.
[84]	Perrin, J.; Ahmed, S.; Hunkeler, D. The Effects of Geological Heterogeneities and Piezometric Fluctuations on Groundwater Flow and Chemistry in a Hard-Rock Aquifer, Southern India. Hydrogeol. J. 2011, 19, 1189.
[85]	Senthilkumar, M.; Arumugam, R.; Gnanasundar, D.; C Thambi, D.S.; Kumar, E.S. Effects of Geological Structures on Groundwater Flow and Quality in Hardrock Regions of Northern Tirunelveli District, Southern India. J. Earth Syst. Sci. 2015, 124, 405–418.
[86]	Abba, S.; Hamelin, B.; Michelot, J.-L.; Garcin, Y.; Deschamps, P. Water Budget of Tropical Volcanic Lakes in Center-North Cameroon: Reconciling the Stable Isotope and Chloride Mass Balance. Hydrol. Process. 2023, 37, e14923.
[87]	He, X.; Li, P.; Ji, Y.; Wang, Y.; Su, Z.; Elumalai, V. Groundwater Arsenic and Fluoride and Associated Arsenicosis and Fluorosis in China: Occurrence, Distribution and Management. Expo. Health 2020, 12, 355–368.
[88]	Abu-Bakr, H.A. el-Aziz Groundwater Vulnerability Assessment in Different Types of Aquifers. Agric. Water Manag. 2020, 240, 106275.
[89]	Braga, A.C. de O.; Francisco, R.F. Natural Vulnerability Assessment to Contamination of Unconfined Aquifers by Longitudinal Conductance–(s) Method. J. Geogr. Geol. 2014, 6, 68–79.
[90]	Caprario, J.; Rech, A.S.; Finotti, A.R. Vulnerability Assessment and Potential Contamination of Unconfined Aquifers. Water Supply 2019, 19, 1008–1016.
[91]	Foster, S.S.D. Fundamental Concepts in Aquifer Vulnerability, Pollution Risk and Protection Strategy. In Proceedings of the Vulnerability of Soil and Groundwater to Pollutants; The Hague, 1987; pp. 69–86.
[92]	Rudd, H.; Neal, A.; Genereux, D.P.; Shea, D.; Nichols, E.G. Vulnerability of Wells in Unconfined and Confined Aquifers to Modern Contamination from Flood Events. Sci. Total Environ. 2023, 901, 165729.
[93]	Sathish, S.; Elango, L. Groundwater Quality and Vulnerability Mapping of an Unconfined Coastal Aquifer. J. Spat. Hydrol. 2011, 11.
[94]	Tesoriero, A.J.; Inkpen, E.L.; Voss, F.D. Assessing Groundwater Vulnerability Using Logistic Regression. In Proceedings of the Source Water Assessment and Protection 98 Conference; Dallas, TX, 1998; pp. 157–165.
[95]	Vasileva, T.; Valtchev, S.; Toteva, A. Regional Characterization of the Vulnerability of the Unconfined Groundwaters in Bulgaria. Geol. Balc. 2023, 52.
[96]	Abd-Elhamid, H.F.; Abdelaal, G.M.; Abd-Elaty, I.; Said, A.M. Evaluation of Groundwater Vulnerability to Seepage from Open Drains Considering Different Pumping Schemes in Unconfined Aquifers. In Proceedings of the Twenty-First International Water Technology Conference, IWTC21,; Ismailia, Egypt, 2018; pp. 28–30.
[97]	Omezuruike, O.I.; Damilola, A.O.; Adeola, O.T.; Fajobi, E.A.; Shittu, O.B. Microbiological and Physicochemical Analysis of Different Water Samples Used for Domestic Purposes in Abeokuta and Ojota, Lagos State, Nigeria. Afr. J. Biotechnol. 2008, 7, 617–621.
[98]	Oladeji, A.; Adeleye, A.O.; Bate, G.B.; Sadiq, I.S.; Amoo, F.K.; Raji, M.; Isiaq, S.M.; Abubakar, Y.B. Groundwater Quality Assessment: Physicochemical and Bacteriological Evidences from Hand-Dug Wells in Gaya Town, Nigeria. SLU J. Sci. Technol. 2021, 2, 16–24.
[99]	Viban, T.B.; Herman, O.-N.N.; Layu, T.C.; Madi, O.P.; Nfor, E.N.; Kingsly, M.T.; Germanus, B.; Victor, N.N.; Albert, N. Risk Factors Contributing to Microbiological Contamination of Boreholes and Hand Dug Wells Water in the Vina Division, Adamawa, Cameroon. 2021.
[100]	Fodouop, S.P.C.; Gingir, B.; Nodem, S.F.S.; Yaou, F.M.; Roselyne, T.N.; Talom, B.T.; Donatien, G. Water Related Diseases in Adamawa Region, Cameroon: A Prospective and Retrospective Case Study. J. Adv. Microbiol. 2021, 21, 75–85.