PERFORMANCE EVALUATION OF GOBA TOWN WATER SUPPLY DISTRIBUTION SYSTEM OROMIA REGIONAL STATE, ETHIOPIA

Abstract

Goba is a town found in Oromia regional states of Ethiopia, which is south of east from the capital, Addis Ababa which was established in 1962. The existing water distribution network of Goba town was designed and constructed in 1984, where the population was about 22,963. Now the population is doubled to 44,622, whereas the water distribution network remains unchanged. Shortage of water supplies for the recent two years and intermittent water supply on the rainy season (due to siltation) were one of the major challenges facing Goba town. This study aimed at evaluating the performance of water supply distribution system, the existing water supply coverage of the town and water losses. The data used includes, annual water production and consumption, surveying data and geometrical properties of pipes from design. For the data analysis, AWWA water audit and EPANET2.0 software’s were used. Discussions were made with local experts and communities to support the qualitative analysis. From the result of the analysis, it was observed that the total water loss in Goba town water supply distribution system is moderate reaches up to 29.1% of the total system input volume and about 27.3% of the total system loss is real losses and 0.4% apparent losses. Besides, the average daily per capita water consumption of the town is 23 liters/person/day which is below the standard. In this paper the modeling of the system as continuous supply system was made, depending on the future water consumption and availability of water. The results depict that the existing system has the ability to serve the present population of the town and also capable of meeting the future extension water demand of the 2025 year. The output values of velocities are parallel reasonably to the assumed limits of velocities (0.4 m/s to 1.5 m/s) to avoid stagnation and water quality problems and also the pressure values are 5% below and 95 % are within the recommended range of country manual standard. Overall it is within the limits of the design pressures in the residential areas. In conclusion the performance of the existing distribution network under current water demand is safe concerned with sources and more focus should be made around the intake areas to get fully design discharge of 42 l/s and to protect entry of sediments from the upstream side of the system and further study is recommended to appropriate improvements.