Hydraulic Performance of Gimbi Town Water Distribution Network
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Date
2020-01
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Addis Ababa University
Abstract
Assessment of hydraulic performance of water supply distribution system to address water distribution bottlenecks within an urban water supply system is important. This can be achieved through investigating the status of the existing distribution system of the network. The main objectives of this study is to assess sustainability and to identify the challenges of Gimbi town WDS. The major problem found in this area is bursting and leakage problem of the pipe system in the distribution network resulting the system to deliver insufficient amount of water to the consumer. To examine the hydraulic performance of the water distribution network, water GEMS modeling was used and the model result is compared with the allowable pressure value and velocity in the distribution system. From the hydraulic analysis all of the velocity in the system is less than 0.6 m/s. It is also identified that 48% of the Nodes in the distribution system has maximum pressure head above 70m and 1% of the Nodes has minimum pressure less than15m. From the detailed analysis, the estimated current (2019) maximum water demand of Gimbi town is 5351 m3/d (62 l/s). However, the current (2019) existing surface horizontal centrifugal types of pumps has only maximum capacity 20 l/s. Further, the analyzed water losses result in Gimbi town indicates that about 55% of production is non-revenue water and 60% of non -revenue water is estimated as a real lose. In general, rising in water demand, small capacities of existing pump and large volume of water loss leads to intermittent water supply in Gimbi town. Hence, most of resident are not satisfied from the town water service. To solve this problem, it is significant to rehabilitate the old pipe from distribution network that are more vulnerable by the current pressure and providing pressure reducing valve in the link having high pressure in distribution network to minimize the pressure to an acceptable level that reduce water losses in the distribution network. Accordingly, installation of 4 PRV in the model at different location in the distribution network reduces the system pressure to an acceptable range of pressure value (15m-70 m). Providing water pump that deliver the current maximum day demand of the water (62 l/s) for the town solves water scarcity in the town. Finally, it was recommended for water utility to give more attention to water losses reduction policies and strategies to minimize water loss in the town.
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Keywords
Hydraulic analysis, Water distribution network, WaterGEMS, Gimbi, Water loss