|Title:||Hydraulic Network Modeling of the Existing Water Distribution System of Addis Ababa City (Legedadi sub system as a case study)|
|???metadata.dc.contributor.*???:||Mebrate Taffesse (PhD)|
|Keywords:||Hydraulic;Water Distribution System;Addis Ababa City|
|Abstract:||The primary goal of this study is to review the hydraulic performance of the existing distribution system of the city, Addis Ababa, Legedadi subsystem which is aimed to help the city understand its distribution system needs and assist them in long-term planning of water assets. The scope of the study is to evaluate the performance of the existing drinking water distribution system using hydraulic simulation software in integration with GIS, and recommends the possible remedies to improve the efficiency of the existing system. The hydraulic simulation software used for this study is Water CAD V8i distributed by Bentley Systems. Bentley Water CAD V8i was selected due to ease of model building and operation and its greater programming capabilities as compared to EPAnet. Hydraulic modeling of the system is performed by considering the system as a continuous supply system, and the evaluation process adopted the Extended Period Simulation method. The system has been checked for different scenarios and alternatives to deepen our investigation. Considering, the model is calibrated at specific locations and the results with field measurements show reasonable difference, so that we use some fine tuning using Hazen Williams C –value to align with the field data. As a matter of fact, I have proved that, there is hydraulic inefficiency in the existing water system to serve the city (Legedadi sub system) and to cope with the future demand. The outputs show that the network is exposed to relatively high and low values of pressure and velocity, which have negative effects on the performance of the network as well as in the water quality of the system. Besides, failure is forecasted in considering the age of pipes for reinstallation and maintenance. As a result, Pipes with ages more than 30 years are replaced and over and under sized pipes have been re-sized. Consequently, the Hazen Williams C-value has been totally improved and it enhances the system performance. The evaluation study of the water hammer in the Addis Ababa distribution system, which has been implemented to investigate the effects of this phenomena shows that the water hammer values increase by increasing the velocity of water in pipes, and the values of shock pressures were within the limits of the shock pressures in water pipes systems. In the study, the major hydraulic parameters, the variations, and the relations between them and other factors, which control the performance of the water supply networks are considered and discussed in detail during analysis. To this end, the network is assessed and possible corrections are given for Optimum water supply network even using Darwin Optimum Pipe Network Designer tool so as to at least the system meet the required design criterion as a constraints. Moreover, the Legedadi subsystem has been categorized for 14 optimum Pressure zones with their corresponding Reservoirs (Pumping stations).|
|Appears in Collections:||Water Resource Engineering|
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