Assessment of drinking and irrigation groundwater quality in Bundung-West Coast, Gambia

Abstract

Laboratory investigation performed to examine the suitability of groundwater quality from an open well, cover well and tap water for drinking and irrigation purposes around Bundung West Coast of the Gambia. The overall mean values obtained are; pH (7.89), Temperature (26.5 ^oC), Electrical Conductivity (1070.8 mS/cm), Total Dissolved Solids (696.00 mg/l), Salinity (0.44 %) and Faecal Coliforms (55.2/100ml). The Coefficient of Variability (CV) among samples for each analytical parameter was > 1, reflecting inconsistency among analysed samples. Nitrate (9.2 mg/l), Phosphate (0.81 mg/l), Sulphate (6.2 mg/l), Ammonia (1.61 mg/l), Nitrite (0.010 mg/l), Total Hardness (273.9 mg/l) and Alkalinity113.5 mg/l) had shown high variance among samples in the site (CV >1). Results of Total Hardness (273.9), is indicative of contaminated groundwater. The microbiological properties exposed colonies of microorganisms (coliforms) resulting from contamination by faecal matter or seeping of sewage effluent into the groundwater and hence unfit for consumption. The groundwater samples in the study site were under high salinity class (>2250 μS/cm), unsuitable for irrigation agriculture. The coefficient of variability is > 1, high variance among samples in the entire site. Total Dissolved Solids (CV>1) contents of the groundwater can be fit only for tolerant crops. The findings suggest that groundwater is unsafe for drinking purposes without decontamination, and measures should be in place for quality water for irrigation agriculture.

Keywords: Groundwater, quality indicators, domestic use, Irrigation