Building future resilience in existing developments facing climate change and urbanization: A stormwater management case study in West Melbourne

ABSTRACT

Urban stormwater systems in existing residential developments are increasingly challenged by intensifying rainfall events and growing impervious areas driven by climate change and urbanization. This study evaluates the hydraulic, water quality, and economic performance of Water Sensitive Urban Design (WSUD) retrofits in a 170-hectare catchment in Hoppers Crossing, West Melbourne, Australia. Utilizing high-resolution PCSWMM modelling, multiple WSUD configurations – Rainwater Tanks (RWT), Rain Gardens (RG), and a Hybrid system were simulated under baseline (2020–2024) and projected 2050 and 2070 conditions, considering the SSP2-4.5 long term climate scenario and future urbanization trends. Findings indicate that combined climate and urbanization pressures could increase annual runoff volumes by 84% by 2070. Among all scenarios, implementing RGs in 50% of houses achieved the greatest hydrologic and water quality improvement, but at the highest life-cycle cost. The Hybrid scenario (25% RWT +25% RG) was identified as the optimal solution, reducing total runoff by around 50–60%, while maintaining pollutant-removal outcomes and achieving a moderate 25-year life-cycle cost (≈AUD 10 million). These findings highlight the potential of integrating WSUD strategies into urban planning frameworks to enhance long-term resilience to climatic and developmental pressures while supporting urban water quality and sustainability.