Geo-chemistry and ground water quality analysis of Sheka zone, SNNPR, south west Ethiopia

Abstract

Groundwater refers to all the water occupying the voids, pores and fissures within earth and its source will be various strata of the earth crust. The current concern of world is the issues of water quality binding with human and environmental health that will focus on problem of different chemical contaminants. The study was conducted on ground water of Sheka Zone; SNNPR, South-Western Ethiopia. Thirteen ground water samples were collected from different sampling points. Field and laboratory based measurement was conducted to determine concentration of cations and an anion in water. Suitability of water for drinking was determined by cation and anion measurement followed by comparing with WHO GVs. SAR, SSP, RSC, MH and KR analysis were conducted to evaluate suitability of water for irrigation. Water type of the study area was determined by using AQUACHEM V.4 software that develops piper diagram. The result indicates that; all water samples had pH value between 6.5 and 7.5, which is below WHO standard. The EC of sampled water is below WHO standard (250 NTU). TDS of water is below the GV (<500 mg/L) and it is fine while Temperature of four sampled water is above WHO GV. Nitrate concentration in one hand dug well in Masha Woreda was raised with value of 11.4 mg/L. Calcium ion concentration is between 5.8 mg/L and 32.70 mg/L, Magnesium ion ranges from 1.02 to 3.41 mg/L. Average concentration of Sodium ion is 4.04 mg/L. Six water samples had Iron concentration above WHO GV (0.3 mg/L) with maximum concentration of (1.72 mg/L) in hand dug well of Masha Woreda. Five water samples exhibited high concentration of Manganese above WHO GV (0.4 mg/L). Maximum Manganese concentration (1.92 mg/L) is recorded in hand dug well of Masha town. Alkaline earth metals dominate the hydrological face of water in the study area. Generally, water type of area is Ca-HCO3-SO4. Except two water samples with SSP value >60, almost all water are suitable for irrigation use. SAR value of all water samples indicates; the water is safe for irrigation. MR value of 12 water samples indicate <50 and this confirms the suitability of water for irrigation use. Generally, it is possible to use ground water of Sheka zone for drinking with minor treatment alternatives and fully possible to use for irrigation purpose.