Water-Sensitive Urban Design (WSUD) Performance in Mitigating Urban Flooding in a Wet Tropical North Queensland Sub-Catchment

Sher Bahadur Gurung; Robert J Wasson; Michael I Bird; Ben Jarihani

doi:10.3390/hydrology12060151

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Water-Sensitive Urban Design (WSUD) Performance in Mitigating Urban Flooding in a Wet Tropical North Queensland Sub-Catchment

Journal article

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Water-Sensitive Urban Design (WSUD) Performance in Mitigating Urban Flooding in a Wet Tropical North Queensland Sub-Catchment

Sher Bahadur Gurung, Robert J Wasson, Michael I Bird and Ben Jarihani

Hydrology, Vol.12(6), pp.1-30

2025

DOI: https://doi.org/10.3390/hydrology12060151

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Abstract

urban flooding

water-sensitive urban design

grey infrastructure

flood mitigation

tropical catchment

Existing wet tropical urban drainage systems often fail to accommodate runoff generated during extreme rainfall. Water-sensitive urban design (WSUD) systems have the potential to retrofit the existing urban drainage system by enhancing infiltration and retention functions. However, studies supporting this assumption were based on temperate or arid climatic conditions, raising questions about its relevance in wet tropical catchments. To answer these questions, in this study a comprehensive modelling study of WSUD effectiveness in a tropical environment was implemented. Engineers Park, a small sub-catchment of 0.27 km2 at Saltwater Creek, Cairns, Queensland, Australia was the study site in which the flood mitigation capabilities of grey and WSUD systems under major (1% Annual Exceedance Probability—AEP), moderate (20% AEP), and minor (63.2% AEP) magnitudes of rainfall were evaluated. A detailed one-dimensional (1D) and coupled 1D2D hydrodynamic model in MIKE+ were developed and deployed for this study. The results highlighted that the existing grey infrastructure within the catchment underperformed during major events resulting in high peak flows and overland flow, while minor rainfall events increased channel flow and shifted the location of flooding. However, the integration of WSUD with grey infrastructure reduced peak flow by 0% to 42%, total runoff volume by 0.9% to 46%, and the flood extent ratio to catchment area from 0.3% to 1.1%. Overall, the WSUD integration positively contributed to reduced flooding in this catchment, highlighting its potential applicability in tropical catchments subject to intense rainfall events. However, careful consideration is required before over-generalization of these results, since the study area is small. The results of this study can be used in similar study sites by decision-makers for planning and catchment management purposes, but with careful interpretation.

Details

Title: Water-Sensitive Urban Design (WSUD) Performance in Mitigating Urban Flooding in a Wet Tropical North Queensland Sub-Catchment
Authors: Sher Bahadur Gurung - James Cook University
Robert J Wasson - James Cook University
Michael I Bird - James Cook University
Ben Jarihani (Corresponding Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
Publication details: Hydrology, Vol.12(6), pp.1-30
Publisher: MDPI AG
Date published: 2025
DOI: 10.3390/hydrology12060151
ISSN: 2306-5338
Copyright note: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Data Availability: The field data used in this study are available from the corresponding author upon request.
Grant note: The authors gratefully acknowledge the support of James Cook University for providing the International Research Training Program (IRTPS-081386F) for funding this research. Additionally, the authors would like to acknowledge the Cairns Regional Council (PD23041 Saltwater Creek Flood Mitigation Project) and the Queensland Government Department of Environment and Science for funding this project. Furthermore, the authors would also like to thank the Hunter Research Grant [00117J] for providing the additional funds to purchase the software tools.
Organisation Unit: School of Science, Technology and Engineering; Sustainability Research Cluster
Language: English
Record Identifier: 991136703502621
Output Type: Journal article