Hydraulic Performance and Evidence–Based Network Management of Nyakanazi Water Distribution Network in Kagera, Tanzania

Abstract

Access to safe and reliable drinking water remains a persistent challenge across rural sub-Saharan Africa, especially in Tanzania where most rural water supply systems exhibit unbalanced pressure regimes, low flow velocities, and high non-revenue water losses largely due to the absence of systematic hydraulic analysis and evidence-based network management. Consequently, the objective of this paper was to evaluate hydraulic performance and evidence-based network management of Nyakanazi water distribution network in Kagera, Tanzania by using a calibrated EPANET 2.0 model. The model performance was evaluated using the Coefficient of determination (R²) and Nash-Sutcliffe Efficient (NSE). The model performance results indicated R2 = 0.838 and NSE =0.814 during calibration and R2 = 0.84 and NSE =0.85 during validation. The baseline simulation results revealed that only 62.1% of nodes operated within the design pressure range of 20–54 m, 14% exceeded 60 m, 1.4% fell below 15 m, 55.58% of pipes operated below the 0.5 m/s self-cleaning threshold, while 3.49% exceeded 2 m/s velocity. The pipe diameter optimization for nodes raised the pressure from 62.1% to 78.2%, excessive-pressure nodes decreased from 14% to 4%, sub-threshold velocity pipes decreased from 55.58% to 25.4%, and all over-velocities were eliminated. It is recommended that undersized pipe mains be increased and pressure-reducing valves be installed in high-pressure zones to improve the hydraulic performance of the Nyakanazi water distribution network.