Comparative Performance Evaluation of Home-Based On-Site Stormwater Detention Systems across Different Terrace Housing Types using SWMM Simulation

Abstract

Urban flooding remains a persistent challenge in tropical regions, primarily driven by rapid urbanization and the expansion of impervious surfaces that restrict natural infiltration. To address this, decentralized stormwater management practices such as home-based on-site detention systems have been adopted to reduce surface runoff at the property scale. This study compares the performance of a modular on-site detention system, the StormPav system, modelled beneath six common terrace housing types in Malaysia, namely double-storey corner, double-storey intermediate, single-storey corner, single-storey intermediate, semi-detached, and bungalow units. Using the Storm Water Management Model, 72 simulation scenarios were developed to evaluate the influence of housing typology, contributing catchment ratio, and storm duration on peak discharge reduction. Design storms of 5, 10, and 15 minutes corresponding to an intensity of 10-year Average Recurrence Interval were simulated. The results show that the StormPav system effectively mitigates peak discharge for all housing types, with significant improvements when the contributing catchment ratio exceeds 50%. Among the configurations tested, the double-storey corner unit demonstrated the highest detention efficiency, achieving a 30–35% reduction in post-development peak discharge compared with pre-development conditions. The novelty of this work lies in the systematic evaluation of a modular on-site detention system across diverse terrace typologies using the stated public-domain software, providing comparative insights into decentralized stormwater performance that can inform urban flood mitigation strategies in tropical environments. The findings highlight the potential of decentralized on-site detention systems to enhance flood resilience in tropical terrace developments.