Investigations of Physico-Chemical Parameters and its Pollution Implications of Elala River, Mekelle, Tigray, Ethiopia

Abstract

The purpose of the study was to assess the water quality parameters of Elala River found in Mekelle, Tigray, Ethiopia. Four sampling sites were chosen spatially along the water course to reflect a consideration of all possible activities that are capable of affecting the quality of the river water. The water samples were collected monthly for three consecutive months (March to May, 2014) at the four sampling sites. In order to understand the characteristics of Elala River, principal component analysis (PCA) was utilized using 22 water quality parameters: water temperature, electrical conductivity, turbidity, pH, total solids, total suspended solids, total dissolved solids, total alkalinity, total hardness, calcium, magnesium, chloride, sulfate, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen, total nitrogen, dissolved oxygen, biological oxygen demand, chemical oxygen demand, orthophosphate and total phosphorus. Among the 22 studied water quality parameters: electrical conductivity (904.11 to 2156.11 μS/cm), turbidity (21.07 to 34.99 NTU), total dissolved solids (700.22 to 1328.22 mg/L), total alkalinity (131.85 to 267.26 mg/L), total hardness (198.67 to 478.67 mg/L), chloride (47.32 to 259.43 mg/L), calcium (65.13 to 146.99 mg/L), chemical oxygen demand (16.02 to 32.53 mg/L), sulphate (271.82 to 384.07 mg/L), nitrate-nitrogen (6.82 to 62.38 mg/L), orthophosphate (0.03 to 0.14 mg/L) and total phosphorus (0.04 to 0.19 mg/L) were above the prescribed limit of WHO guidelines for drinking purposes, while all analyzed water quality parameters fall within the FAO standard limit for irrigation purposes. The water is thus not potable for domestic purposes without some forms of physical and chemical treatment while it is useful for agricultural purposes. Keywords : Elala River, Water quality, Correlation Matrix, Principal Component Analysis, Mekelle, Ethiopia.