Hydraulic modelling of water supply distribution network, a case study in jimma town

Abstract

Water supply distribution system modeling is a method of representing the real system, analyzing and approximating the real water supply distribution system behavior and operating conditions using computer softwares to solve short comings facing water utilities. Some districts like Saris/Sar Sefer/ and some high elevation areas in Jimma Town are facing lack of an access of potable water supply. As a result, the people living in these areas are travelling more than a kilometer to fetch water from springs around Jimma Town, but there are no real evidences which show the real causes of the problems; because there were no studies conducted on the distribution system of Jimma Town. So to identify the main causes for the water shortage at the mentioned areas, to assess the operating condition and hydraulic behavior of the distribution system, to identify problems related to flow and pressure, to evaluate and improve the current performance of the distribution system and to simulate the future condition of the system, it is found crucial to prepare this hydraulic model for Jimma Town Water Supply distribution system. The objective of this study is to model the entire water supply distribution network of Jimma Town from the treatment plant Clear water well to the customers and to analyze and evaluate the performance of the system under various physical and hydraulic conditions including fire flows. The study does not include water quality aspects and energy analysis. The model is prepared using the combination of waterGEMS, AutoCAD, waterCAD and GIS softwares. This study is conducted with the aim of enabling JWSSE operators to ensure the safety of the distribution system without wasting time and energy; because it is possible to manage the system simply on a computer using the model once the WDN model is linked to GIS, water billing and other information management systems of the utility. To prepare the model, different primary and secondary data were collected and analyzed. Then after running the model for both steady state and EPS, low pressure values around Gebrel Tank, high velocity and head loss through the gravity main, and low velocities through most of the pipes were observed. Finally, it’s concluded that even though the main problem of potable water shortage is pressure deficit, the main from the old treatment plant to Gebrel Tank might be closed. Then solutions are suggested using different scenarios.