Groundwater Quality Assessment in a Coastal Sand Aquifer: Implications for Drinking Water and Agricultural Use

Abstract

In many countries, specifically those located in semi-arid zones, groundwater is the major source of drinking water, domestic and agriculture use. The present hydro geochemical study was carried out in the coastal sand aquifer of Thiaroye Dakar, Senegal. A total of 36 groundwater samples were collected from different dug wells, piezometers and boreholes in the study area to decipher hydro geochemistry and groundwater quality for determining its suitability for drinking and agricultural purposes. The analytical results of hydro geochemical parameters such as Na + , Ca 2+ , Mg 2+ , Cl - , SO4 2- of groundwater samples in the study area reveals that over 66% were found to be well within the safe range with respect to the world Health Organization for drinking water indicating that most of groundwater sampling sites are fit for drinking with respect of these parameters. The K + concentrations show that 56% of groundwater is suitable for drinking water. On the other hand, NO 3 - concentration show high levels exceeding the maximum permissible limits for drinking standard at almost 61% of groundwater samples indicating groundwater which is unfit for drinking water thus suggesting the need for treatment or precautionary measures to use for drinking water purpose. The TDS and EC values of groundwater indicate respectively that 69.5 and 61% are suitable for drinking water. According to the irrigation quality parameters such %N, SAR, RSC, KR and Ca 2+ /Mg 2+ ratio it was demonstrated that over 80% of groundwater samples in the study area are suitable for irrigation purpose. Furthermore, the interpretation of graphical plots such as Wilcox and US Salinity Laboratory for the classification of groundwater shows that most of the groundwater samples in the study area are suitable for irrigation purpose except for few groundwater samples.