ASSESSMENT OF SURFACE WATER QUALITY AND POLLUTION CONTROL STRATEGIES USING QUAL2Kw MODEL: A CASE STUDY OF TIKUR WUHA RIVER; HAWASSA, ETHIOPIA

Abstract

River water pollution is caused by both natural and artificial activity, such as waste generated from urban area and agricultural lands. The water quality model using QUAL2Kw was conducted to assess the water quality status of Tikur Wuha River and pollution control strategies in Hawassa, Ethiopia. Water samples from this river were collected on March 2023 at different monitoring stations along the river, and their quality was analyzed. The study result indicated that all the measured parameters satisfied the guidelines of the WHO and Ambient Environment Standards for Ethiopia except BOD5, TSS, and PO4 -3 in the study period. The concentration of DO were meet the permissible limit and two sampling station were below the minimum limit. The measured water quality of the river was appropriate for agricultural activity at all sampling points. The model was applied to simulate the water quality parameters such as flow rate, water temperature, EC, DO, BOD5, pH, TSS, ammonia-N, nitrate-N, and phosphate. The model represented the measured data quite well with some exception. In this study, a stream water quality model, Q2Kw, was used to predict the river water quality using the data collected in dry season. The results from the calibrated model indicate that the model was able to appropriately predict the pollution of the river with |PBAIS| and R 2 values of 1.02% (0.999), (0.65), 8.87% (0.6), and 0.71%, respectively, for temperature, DO, EC, and pH. The model can be applied successfully to generate future scenarios for the study area and applicable to assess the effect of various pollution controls and supporting in-stream measures on key water quality parameters. In general, the study results indicate that proper waste management should be adopted to prevent the continued deterioration and improve the water quality condition of the Tikur Wuha River