Modeling on comprehensive evaluation of water quality status for Abay River, Ethiopia

This study was a systematic evaluation of the physicochemical status of the Abay River's water quality in Ethiopia. To analyze the quality of this river, water samples were collected from various points of the river and tested during the dry season for different physicochemical quality parameters. Besides, samples were taken from point sources such as industrial waste and urban sewage to evaluate their impact on the river. This study involved assessing surface water physical and chemical parameters at 12 different points upstream, downstream, and at mixing sites. Multi-probe and laboratory analysis were used to measure the physical–chemical characteristics. Water temperature, dissolved oxygen, total dissolved solids, electrical conductivity, salinity, and pH were measured by a multimeter probe onsite. Whereas the other parameters such as turbidity, biological oxygen demand, chemical oxygen demand, and ammonia were measured using the laboratory. Water temperature (22.2–25.5 ℃), total dissolved solids (117–753 mg/L), turbidity (12.72–240 NTU), dissolved oxygen (2.5–7.8 mg/L), pH (6.5–7.96), electric conductivity (180–1158 µS/cm), salinity (0.11–1.5 mg/L), bio-chemical oxygen demand (5.3–50 mg/L), chemical oxygen demand (16–151 mg/L) and ammonia (0.012–56 mg/L). Poor water quality was observed at sampling points 2, 5, 7, 8, 9, 10, and 11 due to the entry of unregulated effluent discharges from Habesha, Bahir Dar tanneries, Bahir Dar textiles, and the municipal ditch of Bahir Dar. Based on this, it can be concluded that the water is unfit for drinking purposes without treatment.