Performance Impacts of Rainwater Tanks on Stormwater Drainage Systems

Abstract

This article explores the impact of using rainwater tanks on the performance of a stormwater drainage system and the possible challenges posed by climate change and future rainfall projections. This project examines a residential development in Aldinga, South Australia. The study sets clear research objectives that include the creation and simulation of drainage systems with different conditions (e.g., with and without rainwater tanks, historical data, and projected data). The aim is to analyze performance changes in the drainage network after the inclusion of rainwater tanks. Furthermore, the incorporation of projected rainfall data is considered to study possible implications of climate change on the system performance. The methodology follows a quantitative approach, with data collection, creating different models with the use of software, and simulating various conditions such as storms with different annual exceedance probabilities and varying proportions of roof area connected to rainwater tanks. Several findings are identified in this project. When roof areas of all residential allotments are connected to rainwater tanks, substantial benefits are observed in reducing peak flows within the network and runoff volumes. This proportion of connected roof area is directly correlated with reductions in peak flow. Also, while the use of projected rainfall data slightly affects benefits in peak flow and volume reduction, they will remain relatively high at least until 2050. Other performance features, such as hydraulic gradient line, long sections, and time to peak, are also explored. Study validates the hypothesis that rainwater tanks have a significant impact on runoff reductions and flood management, particularly when 100% of roof area is connected with rainwater tanks. Also, there is an impact when projected data is used, but it remains manageable and should be considered under specific contexts to decide whether these impacts are significant. Several opportunities for future research are suggested. These include the examination of larger areas, projections to a more distant future, the use of different rainfall patterns, and the consideration of extreme rainfall events.

Keywords

Stormwater drainage system / Rainwater tanks / Climate change impacts / Flood management / South Australia

Acknowledgments

We would like to acknowledge the City of Onkaparinga (a local government of South Australia) for provinding us project related information.

Author Contributions

Conceptualization, F.A.C.S. and E.S.; Methodology, E.S. and F.A.C.S.; Software, E.S.; Validation, E.S.; Formal Analysis, E.S.; Investigation, E.S. and F.A.C.S.; Resources, E.S.; Data Curation, E.S. and F.A.C.S.; Writing—Original Draft Preparation, E.S.; Writing—Review & Editing, F.A.C.S.; Visualization, E.S.; Supervision, F.A.C.S.; Project Administration, E.S. and F.A.C.S.

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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