Abstract:
Population growth exploitation in the town usually exerts enormous pressure on existing
water supply systems. The continuous and repeated deficiency in the performance of the
water network becomes one of the most critical issues in the water supply sector that
requires immediate action. Asella town water supply system has problems related to water
supply coverage, water quantity, velocity, and system pressure. The main objective of this
study is to evaluate the hydraulic performance of Asella town’s existing water supply
distribution system with respect to pressure and velocity using Bentley Water GEMS v8i
software. Both primary and secondary data were collected and software such as Bentley
Water GEMS v8i software, ArcGIS version10.1, Microsoft office Excel, and Geographic
positioning system Garmin72 (GPS) were used. The average daily per capita water
consumption and water supply coverage of the town in 2020 G.C is 35.31 l/p/d and 42.249%
respectively. The simulated result for extended period simulation at peak hour consumption
showed that the performance of distribution system related to pressure 47.08% for pressure
value (<15m), 32.92% for pressure value (15-60m) and 20% for pressure value (>60m) head
and the pressure at minimum consumption hour is 10% for pressure value (<15m), 45.85%
for pressure value (15-60m) and 44.15% for pressure value (>60m. The velocity of pipe flow
at peak hour consumption showed that 79.56% for velocity (<0.6m/s), 14.09% for velocity
range (0.6-2m/s) and 6.35% for velocity (>2m/s). From the total 650 nodes in the model, 306
nodes receive water with less than 15m pressure head of water and it indicates the critical
point showing that needs a modification. The average annual water loss in Asella town is
35.24% showing that needs a matter of concern. The amount of water which actually reached
the consumers in average from 2016 G.C to 2020 G.C is 64.76% of the total annual water
production. It is recommended that, the water utility have to be add new water source to
deliver adequate water and add parallel pipes or increasing its diameter to deliver water
with the required pressure.
