Abstract

Twenty groundwater samples were collected from hand dug wells in North-Eastern parts of Gombe town for the purpose of evaluating its quality for culinary and agricultural uses. The area studied is bounded by latitude 11° 09’ - 11° 27’ and longitude 10° 15’ - 10° 27’ covering an area of about 940 Km². Quantitative analysis of the water samples was carried out using Atomic Absorption Spectrometry (AAS) and Flame photometry while RockWare Aq•QA spreadsheet for water analysis was utilized in the evaluation. Three water types were identified, CaCl, Ca - HCO₃ and NaCl.  Total carbonate ranges from 27.393 - 239.27 mg/L and salinity hazard ranges from low to medium. The low salinity type of water identified has no detrimental effects on crop while for medium salinity waters, detrimental effects are expected on crops that are sensitive to salinity. Dissolved solid ranges from <200 and 200 - 500 mg/L respectively, Sodium Absorption Ratio (SAR), Exchangeable Sodium Ratio (ESR) and Magnesium Hazard (MH) ranges from 0.832 - 4.13, 0.292 - 3.968 and 0.086 - 82 respectively. The variation in the chemical composition of groundwater in the study area may be due to leaching of terrestrial salts mostly within the Gombe formation, extensive use of fertilizers and ion exchange between soil minerals and water. The examined groundwater quality is suitable for domestic and agricultural uses except in some locations from Gombe formations where detrimental effect is expected on crops that are sensitive to salinity.

Key words: Hydrogeology, sodium adsorption ratio (SAR), detrimental effect (DE).