17. Evaluation of the Hydraulic Performance of the Kombolcha Town Water Supply Distribution System, Ethiopia

In this study, the hydraulic performance of the existing water supply and distribution network of Kombolcha town was analyzed by using WaterGEMS. The WaterGEMS model was used for automated calibration and analysis of the hydraulic parameters of water supply distribution systems. At selected nodes, the developed model was calibrated to reduce the difference between the measured and simulated pressures. The water supply coverage of the town was only 69.4%, which is extremely low when compared to the country’s urban water supply coverage standard. The water demand was determined to be 50 L/day, which is less than the community’s actual water consumption. The water balance analysis revealed that 67.1% of water production is billed quantity and 32.9% is nonrevenue water (NRW). The results from the simulation of the existing water supply distribution system revealed that during peak hour demand, 23.1% of the junctions have low pressure (15 m H₂O), and 67.4% of the junctions have high pressure (> 60 m H₂O). The hydraulic performance analysis indicated that 83.5% and 24% of the total pipes have velocities below 0.6 m/s at minimum and peak demands, respectively. The study concluded that the hydraulic performance of Kombolcha’s existing water supply distribution systems is below expectations. As a result, high pressures in the distribution system should be managed with pressure-reducing valves. Furthermore, low pressure should be improved by making existing borehole rehabilitation more efficient to meet the town’s peak water demand.