Hydraulic evaluation of water supply and distribution systems: case study of Lawra township water supply system in the Upper-West Region of Ghana

Abstract

Population growth, urbanization, and people’s preferences for water to be brought closest to the home, compel operators with little or no technical know-how on Water supply and distribution systems (WDSs) hydraulics to often introduce new nodes into the network to extend water to consumers. The outcome is operational challenges with some areas not getting adequate supply because of inappropriate pipe routing and sizing, and pressure build up in some sections resulting in pipe bursts during operation. The study evaluated the hydraulic performance of the Lawra township water distribution system for improved service delivery using hydraulic-based models. The Flowius application, Google Earth, Geographical information system (GIS) were the data collection tools employed, while EPAnet and Microsoft Excel software were used to analyse the data. The hydraulic parameters within a 24-hour period in the existing and proposed network were monitored. The existing system runs for a maximum of five hours (00:00am-05:00am) when tested with pressure value (5.3 m) not meeting the minimum pressure requirement of 10 m. The remaining hours of the day depicted negative pressures signifying system unbalance. There were significant head losses in all the three (3) zones (A 24.25 m/km, B 161.66 m/km and C 72.96 m/km) with zone B recording almost thirty-two (32) times higher than the recommended standard of 5 m/km. Series of velocity fluctuation occurred (0m/s – 2.81m/s) across the entire network during the simulation period. The existing network coverage is 70 % with 1360 households. The remodelled network, using EPAnet software for improved performance, was balanced with hydraulic parameters (pressure, velocity and head loss) meeting designed standards and peak hourly demand occurred at 18:00 hours across all the three (3) pressure zones.