MODELING OF WATER SUPPLY DISTRIBUTION SYSTEM USING WATER GEMs: CASE OF DESSIE TOWN, ETHIOPIA

Abstract

The thesis focused on the water supply distribution system of Dessie town, capital city of South Wollo. The Dessie water supply system has five zones according to pressure and location of service reservoirs. The general aim of this study is to evaluate the water supply distribution network system for the case study of Dessie town by using Water Gems modeling. To analyze and improve the existing water supply distribution system, a model was developed using Water Gems software. Steady state simulation and extended period simulation has been carried out for calculation of hydraulic parameter such as pressure head, velocity and loss. The model analysis result showed the different problems of the system. These are aged pipes, low velocity, undersized pipes, low pressure, and high pressures and not install enough pipe line for the expansion part of the town. The model run was performed for different scenarios to analyze the system model, what if conditions. These scenarios are steady state simulation average daily demand alternatives as base scenario, extended period simulation peak hour demand as child scenario and extended period simulation mini hour demand as child scenario. Comparing representative samples of the distribution main‟s pressure field-test with the model-simulated values showed a reasonable and small difference to calibrate the model. Water audit software was also used to analyze water loss components and the efficiency of the system was evaluated using different performance indicators. Nearly 24.3% of the total water production is loss at different level of distribution system before reaching to the consumer. The main reasons for the high loss of water in Dessie town water supply system are poor maintenance and insufficient financial resources of the utility.