Hydraulic modeling of water supply distribution Network: a case study on debre birhan town, amhara Regional state, ethiopia

Abstract

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. Debre Birhan Town has been experienced frequent and regular disruption of water because of hydraulic problems related to pressure and velocity during high consumption period and at night time. This study was conducted in Debre Birhan Twon and the aim of the study was to model the existing water distribution system for steady-state and extended period simulation and evaluating hydraulic performance of the system. For conducting this study, both primary and secondary data were collected and software such as waterCADV8i, ArcGIS version9.3, EndeNotex2, and Geographic positioning system Garmin72 (GPS) were used. The study was carried out by selecting pipes having diameter greater or equal to 80 mm in diameter. The simulated result for both steady state and extended period simulation showed that the performance of distribution system related to pressure 24.74% for pressure value (<15m), 74.24% for pressure value (15-60m) and 0.1% for pressure value (>60m) head and the velocity of pipe flow showed that 76.92% for velocity (<0.6m/s),18.18% for velocity range (0.6-2m/s) and 4.89% for velocity (>2m/s). Those problem are resulted from incorrect nodal placement and improper pipe connection during designing the system and when expanding the network to the newly settlement area. The total average per capita consumption of the Town in the year 2015 was 15.62 l/p/d which shows lower performance compared to 20 l/p/d which is set by WHO (2008). The potential of the projected water demand increment in Debre Birhan Town is greater than the current supply potential of water sources. The water demand for the Town of Debre Birhan averagely increases by32.21% every five years up to the year 2030.The performance of the model was evaluated using model evaluation statistics. The value of the coefficient of determination ( 2 R ) for pressure calibration was 0.98