Hydraulic Performance Evaluation Of Existing Water Supply Distribution Network; The Case Of Durame Town, Snnpr, Ethiopia

Abstract

The occurrence of ephemeral/transient flow in water distribution system creates large pressure forces and rapid fluid accelerations or deceleration that can cause failure of hydraulic equipment in a pipe network if adequate transient control measures are not in place. Safe and adequate delivery of water to a consumption node is an essential function of water distribution network. However, throughout the world especially in developing countries, the hydraulic performance of water distribution network is inadequate to transfer available water to a consumption node. Therefore, this study aims with the study of hydraulic parameters performance of Durame town water supply distribution network project as the case study. Durame town is the capital of Kembata Tembaro Administrative Zone of the SNNP Regional State. The water supply distribution network of Durame town was designed and constructed in 1983 by different spiritual missionaries. The methods used to carry out this research were desk study to evaluate previous designs, field data collection and data analysis. For conducting this study, both primary and secondary data were collected and hydraulic modeling software tool such as Bentley WaterGEMSv8i, ArcGIS version10.1, Geographic positioning system Garmin72 (GPS) and other relevant materials were used. The study was carried out by selecting pipes having diameter greater or equal to 50 mm in diameter. The simulated result for both steady state and extended period simulation showed that the performance of distribution system related to pressure 36.47% for pressure value (< 15 mH2O), 50.59% for pressure value (15 - 60) mH2O and 12.94% for pressure value (> 60 mH2O) pressure head and the velocity of pipe flow showed that 56.7% for velocity (< 0.6 m/s), 41.7% for velocity range (0.6 - 2 m/s) and 1.6% for velocity (> 2 m/s). Those problems are resulted from incorrect nodal placement and improper pipe connection during designing the system and when expanding the network to the newly established settlement area. The low pressure zone areas around Industrial College and below and above Durame general Hospital did not get water at these junctions during peak hour demand. The per capita domestic water consumption of study area was found to be 15.2 l/c/d in the year 2018. The minimum quantity of domestic water required in urban area of developing country in the radius 0.5 km taken as 20 l/c/day. Regarding to this value, the domestic water supply of Durame town only satisfies 76% of the standard value and the quantity of domestic water required in urban areas of Ethiopia is taken as 50 l/c/day. According to this value, the domestic water supply of Durame town only satisfies 30% of the standard value. The total loss of water in the town for the year was 700289 m3 – 456580 m3 which gives 243709 m3 and approximately 34.8% of the total production. This figure is lower compared with the average for developing countries (35%). The average the amount of water, which actually reached the consumers, therefore accounts for only 65.2% of the total water produced. The potential of the projected water demand increment in Durame town is greater than the current supply potential of water sources. The current water demand is 6,196.75 m 3 /day and the demand at end of design period of 2038 years would be around 22,467.82 m3 /day. Finally, the researcher recommends preventive measures of interruption water supply network using control valves and installing storage distribution balancing tank above the Durame industrial college for delivering enough and sufficient amount of water to the customers