Suitability Analysis Of Groundwater For Drinking And Irrigation Purposes: A Case Of Sabata Hawas District, Oromiya, Ethiopia

Abstract

Groundwater is an important natural resources serving as a reliable source of drinking and irrigation water for many people worldwide. Contamination of groundwater, either from anthropogenic or natural sources has now turned to be a major environmental challenge. Access to quality drinking and irrigation water is of major concern for sustainable development in developing countries like Ethiopia. Pollution of groundwater is the most serious problems affecting the health of the people. Therefore the objective of this study was examining suitability analysis of groundwater for drinking and irrigation uses. Groundwater samples were chemically analyzed for major physicochemical parameters in order to understand the different geochemical processes affecting the groundwater quality. For the purpose of this study10 samples were collected from 10 boreholes and the purposive sampling techniques was applied and 30 boreholes of previous published data by Oromiya water, Mineral and Energy Bauer in Sabata Hawas district also analyzed. The samples were analyzed for Mg2+, Ca2+, Na+ , K+ , Cl, SO42- , HCO3- , CO32- , NO3- , F, PO43- ,NH3,NH4+ , total Iron, total Manganese, hydrogen ion concentration , total dissolved solid , total hardness, electrical conductivity, temperature and turbidity were investigated. The Ethiopian standard (2001) and the WHO (2011) water standards were used as the basis of evaluating the suitability of groundwater for drinking purpose. For irrigation, Electrical Conductivity (EC), Sodium percentage (Na %), Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Kelley’s Ratio (KR), Magnesium Ratio (MR) and Permeability Index (PI) were used to evaluate suitability. Lastly, the result was presented using Aquachem.software V2014.2 in order to showed water type (piper diagram) and Wilcox diagram of sodium hazard versus salinity hazard in the study area. The results showed that the groundwater is hard, alkaline in nature and that most of the samples are within the permissible range of both Ethiopian standard (2001) and WHO (2011). 6.9%,100%, 26.9%, 20%, 20% and 7.14% samples showed concentrations of F- , K+ , Mn2+, total hardness, turbidity, Ca2+ and NO3- respectively were above the guideline value as per WHO and national standards. 15% of the concentration of NH3 and NH4+ were fells out of the WHO guideline recommended for drinking water supply. The quality of groundwater for irrigation purpose is suitable. However, based on Wilcox diagram 12.5% groundwater samples of the study area revealed under high salinity hazard and 10% of magnesium hazard is higher than the recommended and hence it is not suitable for irrigation due to the potential to cause alkaline soil which is known to have low infiltration capacity. Classical hydro-chemical methods revealed five hydro-chemical facies (water types) in the study area, which are Ca-Mg-HCO3, Ca-Na-Mg-HCO3, Ca-HCO3, Ca-Mg-SO4-HCO3 and Ca-Na-Mg-HCO3-Cl .The major ion chemistry analysis revealed that the main composition controlling processes in the study area is rock water interaction. It further revealed that the ionic concentration is due to silicate weathering, carbonate weathering, cation exchange, gypsum dissolution and halite dissolution.