GIS-Hydrogeochemical Model of the Yaound&amp;#233; Fractured Rock Aquifer, Cameroon: Aquifer Setting, Seasonal Variations in Groundwater-Rock Interaction and Water Quality

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From the declaration made by the African Mayors in Senegal; the Mayors and Municipal Health Officers of the Americas in Columbia; the City Executives of Cities and Local Governments of the World in Spain and in the context of the Millennium Development Goals MDG 1&7; there is a need for increased food production in urban and peri-urban areas UPA in the world. Sub-Saharan Africa faces more development challenges than any other major region of the world with most of the people living in slums, without access to adequate food, water, or sanitation. UPA contributes to increased food security, nutrition and livelihoods in a combination of ways giving access to consumer markets; less need for packaging, storage and transportation of food; potential agricultural-related jobs and incomes; non-market access to food for poor consumers; availability of fresh, perishable food. In Abuja FCT, 40% of the populations in UPA are farmers, a reason why the agricultural quality of its groundwater which is used for irrigation begs for our attention. 33% of the fresh vegetables in the Abuja Federal Capital Territory (FCT) are produced in Abuja UPA. In order to assess groundwater for agro-industrial suitability the following were used: Physicochemical parameters (pH, Temperature, Elec-

Section: Kelly's Ratiosupporting

confidence: 87%

Agro-Industrial Groundwater Quality Abuja FCT, Nigeria: An Evaluation for Urban and Peri-Urban (UPA) Agricultural Irrigation

Akoachere¹,

Yaya²,

Eyong³

et al. 2019

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“…In Granite-Gneiss-type rocks, single weathering and erosional processes induce similar geological structures. From field observations, borehole lithostratigraphic sections and by comparing various case studies in similar terrain, a modified hydro-geological conceptual model of migmatite/gneiss-type fractured rock aquifers in Africa postulated by [1] has been adopted in Abuja FCT.…”

Section: Hydrogeologymentioning

confidence: 99%

“…Groundwater when biologically contaminated results in serious health related problems and consequences. Groundwater has been recognized as playing a very important role in the development of Abuja FCT, Nigeria's Capital as many private, government, and households establishments depend solely on hand-dug wells and boreholes for their daily water needs [1]. Therefore, the groundwater biological quality of Abuja FCT can never be over emphasized, since the wellbeing of the citizens of the capital territory, seat of the government of Nigeria, is of strategic importance.…”

Section: Introductionmentioning

confidence: 99%

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Groundwater Biological Quality in Abuja FCT: Myths and Realities of Point and Non-Point Pollution of Fractured Rock Aquifers

Akoachere¹,

Eyong²,

Ngassam³

et al. 2019

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The quality of groundwater is three fold: physical, chemical and biological. For water to be fit for human consumption, it must have satisfied all three quality aspects. Therefore, the groundwater biological quality of Abuja FCT can never be over emphasized since the wellbeing of the citizens of the capital territory, seat of the government of Nigeria, is of strategic importance. There are myths and realities about the biological quality of groundwater in fractured rock aquifers which must be clarified. Groundwater plays a very important role in the development of Abuja, Nigeria's Capital as many private, government, and households establishments depend solely on hand-dug wells and boreholes for their daily water needs. This study evaluates the biological quality using total bacterial density (TBD), total coliform (TC), coliform bacteria (CB), faecal coliform (FC), total bacteria count (TBC), and salmonella species (SS) as biological pollution indicators. From physicochemical parameters: pH ranged from, 4.8-7.9; EC, 13.4-1634 µS/cm; Temperature, 26˚C-36.1˚C and TDS, 17.42-1094.78 mg/L. Groundwater of Abuja FCT is not suitable for drinking as the species had the following concentration and percentages above the permissible limits for drinking water: TC (0-1280) 51.06%, FC (0-170) 19.15%, TBD (0-86.6) 98.94%, TBC (0-5120) 95.74%, CB (0-438) 74.47% and SS (0-223) 69.15%. Groundwater from Abuja FCT Granite-Gneiss fractured rock aquiferous formation is unfit for human consumption and an added danger to humans since it is usually assumed to be safe.

“…of Ca, Mg, and bicarbonate ions. Many African basement aquifers contain groundwater which can be characterized as rock weathering-dominated as discussed in[25] [26][27].…”

mentioning

confidence: 99%

Hydrogeology of Abuja FCT-Nigeria: A GIS Evaluation

Akoachere¹,

Yaya²,

Eyong³

et al. 2019

Self Cite

Groundwater has been recognized as playing a very important role in the development of Abuja FCT Nigeria's capital, as many private and government establishments depend solely on wells for their water needs. Exploitation of groundwater is delicate due to its potency to contamination and difficulty to remediate aquifers. This study is to evaluate the input of the rock formations to the groundwater solute chemistry and groundwater domestic quality using hydrogeochemical tools and physicochemical parameters: pH, EC, Temperature, TDS, Chloro-alkaline indices, Ionic ratios, Gibbs diagrams, Piper diagrams, Durov diagrams and water quality index. From physicochemical parameters: pH ranged from, 4.8 -7.9; EC, 13.4 -1634 µS/cm; Temperature, 26˚C -36.1˚C and TDS, 17.42 -1094.78 mg/L. The major ions fell below WHO acceptable limits. The sequences of abundance of major ions were, K + > Ca 2+ > Na + > Mg 2+ for cations and Cl − >anions. Borehole depths range from 19.5 -34.5 m with static water levels between 3 -12 m.a.m.s.l. Yields were between 3.2 -7.2 m 3 /Hr. Ionic ratios show ninety-five (95%) percent of the groundwater chemistry resulting from chemical weathering of rock-forming minerals through the dissolution of the host rock. The Chloro-alkaline indices: CAI 1 87.23% are positive indicating exchange of Na and K from water with Mg and Ca of the rocks and 12.77% are negative, indicating reverse softening of groundwater in rocks by infiltrating rainwater while CAI 2 85.11% are positive indicating exchange of Na and K from water with Mg and Ca of the rocks and 14.89% are negative, indicating reverse softening of groundwater in rocks by infiltrating rainwater. Thus chloro-alkaline indices indicate the dominance of alkaline earth elements over alkalis in majority of samples due to direct exchange of Ca 2+ and Mg 2+ from the aquifer matrix with Na + and K + from the groundwater. Gibbs How to cite this paper: Akoachere, R.A., diagram revealed groundwater ionic content was as a result of ion exchange from rock-weathering. Piper diagrams give three water types: 75% are CaH-CO 3 , 21.20% are of MgHCO 3 and 3.19% are of Na + KHCO 3 water types respectively. Piper diagrams also give three hydrogeochemical facies in Abuja FCT: 54.25% are of Ca-Mg-Cl-SO 4 , 42.56% are of Ca-Mg-HCO 3 and 3.19% are of Na-K-Cl-SO 4 hydrogeochemical facies respectively. Durov plot shows 20.21% are anion discriminate Ca dominant; mixed water and 63.83% had no dominant ion; simple dissolution. Water quality indices (WQI) values were between −220 -180, Total hardness (TH) values were between 0 -519.12. These WQI and TH values indicate that 69.2% and 47.37% of the groundwater respectively are suitable for domestic purpose. The groundwater in Abuja FCT is acidic to slightly alkaline in nature, soft to moderately hard and of low to high salinity. Major processes controlling the water quality are the weathering of the host rock through mineral dissolution, cation exchange and inverse cation exchange processes. Ion-exchange, simple dissolution and uncommon diss...