Investigation Of The Sustainability Of Urban Water Supply System In Bonga Town, South Western Ethiopia

Abstract

Profound observation and originality of creative study on the harmony of sustainability of urban water supply system is crucial issue to solve the sustainability problem. These effects were due to lack of detail investigation and appropriate design of water supply system aided by updated software packages at global, national and local scale, especially in Bonga town. The existing water supply system of the Bonga town does not delivered to all area of the town particularly newly expanded parts; and not satisfy the current and future water demand of the community. This study was aimed to investigate the sustainability of Bonga town water supply system through technical performance indicators of velocity and pressure. The main input data used were collected from Southern Nations, Nationalities and People’s Regional State Water and Irrigation Development Bureau, Kaffa Zone Water Mine and Energy Department, Department of Kaffa Zone Finance and Economy Development, Bonga Town Water Supply and Sewerage Enterprise, Bonga Town Municipality and field survey data. The application of Water Geospatial Engineering Modeling System (WaterGEMS V8i) with coordination of Geographic Positioning System (GPS Garmin 72), Google Earth, Global Mapper, AutoCAD 2007 and Microsoft Excel 2013 was used to achieve the objective of this study. Model investigation resulted with current maximum daily water demand of 3182.87 m3 /day, thus small service reservoir capacity were observed. For sustainability analysis both steady state and extended period simulation were computed to determine the hydraulic performance indicators. Therefore, the simulation result of existing water supply system pressure water head of 44.98% and velocity of water flow of 92.5% were found out of the allowable range of (15 – 60 mH2O) and (0.6 – 2.0 m/sec) respectively. The sustainability was evaluated using performance indicator parameters of resiliency, reliability and vulnerability value of 0.18, 0.26 and 0.72 respectively, and failed to have a good performances. The most three indicator parameters contributes to verify sustainability index of 0.22 that determines Bonga town water supply system were unsustainable. The redesigned extended period simulation result were indicated that pressure at all junctions and velocity flow of pipe were within a permissible ranges of Ministry of Water, Irrigation and Electricity guidelines. Thus, the extended period simulation result of hydraulic performance pressure and velocity for upgraded system are 99.28% and 92.39% respectively, were identified within acceptable ranges. Therefore, further detail investigation and appropriate redesign of water supply system for the sustainability should be applied.