ASSESSMENT OF URBAN WATER SUPPLY SYSTEM PERFORMANCE: ARBA MINCH TOWN: ETHIOPIA

Abstract

Water distribution systems are the most important urban infrastructure in the world and require huge construction investments. Arba Minch Town has been experiencing failure of the water distribution system due to poor system design and system deterioration. Therefore, this study aimed to model optimal water distribution network by modifying the existing distribution network of Arba Minch Town using WaterGEMS software. The population of the town in 2032 expected to reach 201,814 with an average daily demand of average daily demand of 67.34l/c/d and 36.8 % of water production lost in the distribution system before reaching to the end customers. The town's master plan made it possible to optimally modify the layout of the network, change the pressure zones and change the position of some supply tanks in the existing water networks. It is observed that existing water distribution systems did not cover the existing community like Gurba and Woze kebele due to design problems and pipe size. The modified distribution network has improved the minimum and maximum water flow velocity through providing appropriate pressure in the ranges of 10-70 m head of water. It has been noticed that maximum pressure criteria violation percent was reduced from 35.62 percent to 1.5 percent during minimum flow hours and it also diminished from 32.3percent to 1.08 percent during peak flow. The results also showed that the minimum velocity criteria violation reduced from 17.08percent to 0.07percent during peak flow rate condition. The study concluded that the existing water distribution network in the study area needs to be done of optimal approach by modifying the system to ensure efficient water distribution for the community.