Hydrogeochemical Model and Water Quality of Groundwater in the Granito-Basaltic Fractured Rock Aquiferous Formations in Bafoussam, West Region-Cameroon

摘要

This study determined the hydrogeochemical model of groundwater and groundwater domestic-agro-industrial quality in Bafoussam using hydrogeochemical tools and physicochemical parameters: Ionic ratios, Gibbs diagrams, Piper diagrams, Durov diagrams and water quality indices. From physico-chemical parameters; pH ranged from, 4.47 - 7.84; EC, 10 - 820 μS/cm; Temperature, 22.3℃ - 29.5℃ and TDS, 6.7 - 549.4 mg/L. The major ions fell below WHO acceptable limits. The sequences of major ionic abundance are: Ca~(2+) > Mg~(2+) > K~+ > Na~+ > NH_4~+ , HCO_3~- > Cl~- > SO_4~(2-) > NO_3 > HPO_4~(2-). Recharge by atmospheric precipitation, ion-exchange and simple dissolution processes are responsible for groundwater character, ionic content resulted from ion exchange and rock-weathering. Water types are Ca-HCO_3 and Ca-Cl Hydrogeochemical facies are Ca-Mg-Cl-SO_4 and Ca-Mg-HCO_3. Domestic water quality was determined by use of pH, electrical Conductivity EC, total dissolved solids TDS, total Hardness H_T and water quality index WQI. WQI values ranged from 0 - 42.09 and H_T 67.89 - 339.01 indicating that water is of good domestic quality. Agro-industrial suitability of groundwater was determined using, sodium adsorption ratio SAR, permeability index PI, Magnesium adsorption ratio MAR, percent sodium %Na, Kelly's ratio KR and Residual sodium carbonate RSC and Wilcox diagram; From irrigational water suitability parameters, SAR values ranged from 0.01 - 0 05; %Na 3.69 -15.50; KR 0.005 - 0.023; PI 1.04 - 67.98; MAR 2.89 - 55.27; RSC -5.22 to -0.44 and Wilcox diagram indicate that inorganic groundwater content in the study area is excellent-good for irrigation; this is of significance since Bafoussam a major agroindustrial zone in Cameroon and Central Africa is in the process of developing large scaled irrigation based agricultural projects dependent on use of surface and groundwater. Recharge from precipitation exchanges ions with the weathered country rocks and mixes with regional flow in a generally south-east north-westerly direction by piston flow in the granito-basaltic aquiferous formations in Bafoussam. There is need for detailed studies to determine aquifer characteristics: permeability, transmissivity and storativity, vertical-lateral regional extent of aquifer boundaries, groundwater pollution potentials for biological, organic and trace metals.