Modelling the effect of operational interventions on hydraulic performance of a water distribution system under intermittent conditions

Abstract

Over 1.3 billion people globally rely on intermittent water supplies, a challenge worsened by rapid urbanization, climate change, and environmental pressures, highlighting the need to improve water supply systems to achieve Sustainable Development Goal 6. A comprehensive framework for evaluating hydraulic performance in developing cities is essential to address the limitations of isolated performance indicators and enable equitable transitions from intermittent to continuous water supply. This study proposes a new graphical-numerical approach for assessing the hydraulic performance of water supply systems (WSS) under intermittent conditions, demonstrated using the Kapeeka WSS. Pressure-dependent (PDA) and demand-driven (DDA) analyses in EPANET revealed a rising TWS/TWD ratio leveling off as TWD increased. The Demand Satisfaction Index (DSI) post-extension in 2021 was 0.68, while system curves showed a maximum conveyance of 115.23 m³/h against a 217.76 m³/h demand, improving to 133.4 m³/h after strengthening. Despite these enhancements, 84% of nodes in 2041 had pressures below the required 5m head. The findings highlight that while unplanned network strengthening improves hydraulic capacity, it fails to eliminate intermittent behavior, underscoring the need for comprehensive hydraulic performance assessment during interventions of Water Distribution Network extensions and strengthening to ensure sustainable water supply management.