Hydrogeochemical appraisal of groundwater quality in the Ga west municipality, Ghana: Implication for domestic and irrigation purposes

This study was conducted to appraise the quality of groundwater for irrigation and domestic water supply in the Ga West Municipality, Ghana. A total of 29 borehole water samples were collected for hydrogeochemical analysis and interpreted using hydrogeochemical plots and multivariate statistical analysis. The relative abundance of the major ions in the analyzed water samples were in the order Na+ > Ca2+ > Mg2+ > K+ and HCO3- > Cl- > SO42-. Trilinear Piper plot shows that Na-HCO3-Cl and Na-Ca-HCO3-Cl are the dominant water types in the area. The Ca2+ and HCO3- in these type of waters are primarily from dissolution of carbonate minerals whilst the Na+ and Cl- may have been input from water-rock interaction with granitic rocks, seawater intrusion, and anthropogenic activities in the watershed. All the analyzed physico-chemical parameters are within the acceptable limits of the World Health Organization (WHO) for drinking except TDS, total hardness, Na+, and Cl- which could be as a result of solid waste leachate and marine water intrusion. The samples have low to medium sodium hazard values with high to very high salinity hazard values when plotted on the Wilcox diagram. This suggests that the water is suitable for irrigation purposes with regard to sodium hazard but a mixing of the high salinity water with low salinity water is highly recommended prior to irrigation to reduce the salinity hazard in the area. However, if the crops are salt tolerant, then mixing is not necessary. Three factors explain 99.8% of the total variance and suggest that water-rock interaction is the most important factor that controls the groundwater chemistry. Besides, some contribution from agricultural activities and seawater mixing are the other factors influencing the groundwater chemistry. These factors are indicated by the positive correlation among the individual hydrochemical parameters.