Evaluation of the suitability of groundwater for drinking and irrigation purposes in Jimma Zone of Oromia, Ethiopia

Due to decrease in surface water resources and pollution of these sources, groundwater is becoming more important for drinking and irrigation purposes. Understanding the groundwater quality is important for the protection of public health and sustainable development of water resources. Thus the aim of this study was to assess the suitability of groundwater for drinking and irrigation purposes in Jimma Zone. A total of 32 groundwater samples were collected from seven districts of Jimma Zone in December 2016. The samples were analyzed for selected water quality parameters using standard procedures. The suitability of groundwater for drinking purpose was evaluated by comparing the chemical concentrations with the standard guideline set by World Health Organization. The suitability for irrigation uses was evaluated by calculating Sodium Adsorption Ratio, plotting Wilcox and Unites States Salinity Laboratory Diagrams. Based on the findings, the concentration of Na+ in 25% of the groundwater samples exceeded the maximum permissible value. About 47% of the samples contained excess F- which is a public health concern. The results of the study revealed that 68.8% of the samples were good, 18.8% were moderate and 12.5% were bad water for irrigation uses. High concentrations of F- and Na+ make the water unsuitable for drinking and irrigation uses, respectively in some groundwater samples. Thus, defluoridation of the groundwater is mandatory to use for drinking and alternative surface water sources should be used for irrigation in some identified areas.