EVALUATION OF WATER QUALITY STATUS OF BATENA RIVER USING WATER QUALITY INDEX (WQI): HADIYA ZONE IN ETHIOPIA

Abstract

Batena River is an important river in and around Hossana City. The river's water quality has deteriorated due to waste disposal, dumping of solid waste, soil erosion, urban runoff, and agricultural activities that load pollution into the river. However, the people nearby use the river widely without adequate and reliable information about water quality and pollution status. The aim of this study is to evaluate the water quality status of the river and to analyze its suitability for drinking and irrigation purposes. Six sampling stations were selected and sampling was done twice in each of the wet and dry seasons. Various physicochemical and bacteriological parameters, namely, pH, Turbidity, TDS, EC, TH, DO, BOD, Ca2+, Mg2+, Na+ , K+ , Cl- , CO3 -2 , HCO3 - , SO4 2- , PO4 3- , NO3 - and Fecal coliform were determined for all samples following standard procedures. The findings of the analysis were compared with maximum acceptable limit values recommended by WHO and ESA for drinking and FAO for irrigation. The water quality for drinking purpose was evaluated using the Weighted Arithmetic Water Quality Index (WAWQI) method. WQI values ranged from 195.1 to 283.9 in the rainy season and 56.1 to 126.1 in the dry season. The computed WQI values Indicates that at all sampling sites classified as under ‘unsuitable’ category for drinking purposes in the case of wet season. In the dry season, it varied from poor to unsuitable Category. River water quality for irrigation were evaluated by using irrigation water quality indices, including SAR, RBC, PI, %Na, SSP, KI and MR values, revealed that all river water samples were suitable for irrigation use except magnesium ratio during wet season at sample point BR4. From the analyses, it is understood that Turbidity (95 ± 21.2 to126.5 ± 35 NTU), PO4 -3 (0.33 ± 0.016 to 0.46 ± 0.05mg/L), BOD5 (6.2 ± 0.8 to 11.5 ± 0.8mg/L) and Fecal coliform (31 ± 4 to98 ± 9 CFU/100ml) during the wet season and Turbidity (9.2 0 ± 2.96 to16.2 ± 1.59NTU), PO4 - 3 (0.249 ± 0.02mg/L), BOD5 (6.28 ± 0.34 and 7.08 ± 1.49) and Fecal coliform (12 ± 1 to 52 ± 6 CFU/100ml) during dry season are above the recommended limits that have a significant impact on the river water quality for drinking purpose. This could have been related to the municipal waste, dumping of solid waste, soil and rock erosion, urban runoff, and agricultural activities that load pollution into the river. Finally, the study recommends sustainable management to prevent pollution in Batena River.