Techno-Economic Evaluation of Vegetated Swales for Urban Stormwater Management in South Australia

Abstract

Urban stormwater runoff continues to challenge cities worldwide due to increasing impervious surfaces and intensified rainfall from climate change. Swales—vegetated conveyance channels designed to manage runoff volume and quality—offer a nature-based solution that integrates hydrological function, ecological enhancement, and cost-effectiveness. This study investigates the performance and lifecycle economics of swale systems using a case study in South Australia. A MUSICX model simulation was conducted to quantify pollutant removal and flow reduction, and lifecycle costing was performed to evaluate construction and annual maintenance requirements. Results indicate exceptionally high treatment efficiencies, with over 99% removal of total suspended solids, nitrogen, phosphorus, and gross pollutants, and a 99.09% reduction in runoff volume. The total capital cost of the swale network was estimated at $19,726.50, with annual maintenance at $6157.49. Economic benefits from pollutant removal and avoided downstream treatment were valued at $14,874 per year, demonstrating a favorable benefit-cost profile. The findings underscore the potential of well-designed swales to function as cost-effective, modular components of decentralized stormwater management systems. These results contribute evidence supporting the broader integration of swales into urban planning, particularly in water-sensitive design frameworks seeking to achieve sustainability, climate adaptation, and SDG-aligned outcomes.

Keywords

Swales / Techno-economic analysis / Stormwater management / MUSICX modelling / Green infrastructure / Lifecycle cost / WSUD / Aldinga

Acknowledgments

The authors gratefully acknowledge Chris Chow, Course Coordinator for the Master’s Research Project at the University of South Australia, for his academic leadership and guidance during the early stages of the study. His insights helped refine the research direction and align it with broader program objectives. The authors also thank the academic and technical staff of UniSA STEM for their support throughout the project. Contributions in the form of coursework, modelling advice, and consultations were instrumental in applying theoretical concepts to real-world challenges. The authors further acknowledge the University of South Australia for providing access to licensed software essential to the modelling and analysis tasks of this study. Appreciation is also extended to the City of Onkaparinga for their cooperation and provision of site-specific information, planning data, and background documentation. This support was essential in ensuring that the case study design reflected practical and contextual realities.

Author Contributions

Conceptualization, F.B.d.G. and F.A.A.; Methodology, F.B.d.G.; Software, F.B.d.G.; Validation, F.B.d.G., N.P., R.J.P. and J.K.Y.; Formal Analysis, J.K.Y.; Investigation, N.P. and R.J.P.; Resources, F.B.d.G., N.P., R.J.P. and J.K.Y.; Data Curation, F.B.d.G.; Writing - Original Draft Preparation, F.B.M.d.G, N.P., R.J.P. and J.K.Y.; Writing - Review & Editing, F.B.d.G. and F.A.A.; Visualization, J.K.Y.; Supervision, F.A.A.; Project Administration, F.B.d.G. and F.A.A.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data of this research article may be available upon request to authors.

Funding

This study was completed as a part of Master of Engineering thesis at the University of South Australia and no extra funding was involved.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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