Determination Of Ground Water Type And Quality For Drinking And Irrigation Purposes: A Case Of North Showa Zone, Oromiya, Ethiopia

Abstract

Groundwater is a vital source of water for domestic and agricultural activities in North showa zone due to non-perennial flow of surface water. Thus the present study aims to evaluate the groundwater quality and assess its suitability for drinking and irrigation purposes. A total of 19 groundwater samples were examined for various physico chemical parameters to evaluate the quality and suitability of groundwater for the intended purposes and Na+ and Ca2+ were the dominant cations and HCO3− is the dominant anion in all samples. The suitability of groundwater for drinking purpose was evaluated by comparing the analytical results of different water quality parameters to the Ethiopian standard as well as World Health Organization Standards (WHO, 2006). Hence the study shows that 94.74% and 95.57% of the sample water of the study area meet the WHO and FMoWR (2002) permissible guidelines respectively. Water suitability for irrigation indicates that SAR, %Na and SSP plot, majority of water samples fall under medium saline to low sodium type indicating that water was suitable for irrigation. Based on PI, it was found that ground water was vary from good to moderately suitable for agriculture and there was no much threatening of reduction in permeability of soil. As a whole, the quality of ground water was suitable for agriculture purpose. Piper pilot shows that 26.32% of water samples were Na-Ca-HCO3 water type, 21.05% of water samples were Ca-Na-HCO3 water type, 15.78% of water samples were Ca-Mg-HCO3 water type, and 10.53% of water samples were Ca-Na-Mg HCO3 water type and finally Ca-HCO3-SO4-Cl, Mg-Ca-HCO3-CL, Na-CO3-HCO3, Ca HCO3, and Na-HCO3 water types are totally 26.32% of water samples. Rock-water interaction and cation exchange along groundwater flow path are responsible for the current characteristics of hydro geochemical facies. Water quality index using quality rating scale to evaluate the suitability of water for drinking purpose shows that 36.84% of samples fall in the class of excellent water type, 26.31% of samples fall in the class of good water type and 36.84% of samples fall in the class of moderate water type for drinking purpose