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

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study systematically evaluates the potential of Water Sensitive Urban Design (WSUD) in mitigating urban floods in a wet tropical sub-catchment, focusing on Engineers Park, a small sub-catchment of Saltwater Creek in Cairns, Queensland, Australia. This paper confirms that WSUD integration with existing grey infrastructure significantly reduces peak flow, total runoff volume, and flood extent under major, moderate, and minor rainfall events. However, there are several suggestions for further improvement as follows:

1. The "Study Site" section lacks critical geographic information. Since "ferrosol" is mentioned in line 125, should the soil type be addressed? Additionally, there is a lack of description regarding the terrain conditions of the study area.
2. Lines 137-143 mention the spatial interpolation method for precipitation but lack an explanation of relevant parameters.
3. Lines 212-219 discuss the MIKE+ modeling approach; however, specific parameters and methods for setting up the model are missing.
4. Lines 297-301 provide a vague description of the classification and functions of WSUD systems. It's necessary to clarify the functional mechanisms of each WSUD system.
5. The "Results" section mentions evaluation metrics such as NSE, PBLAS, and RSR, for which the formulas need to be provided.

There are also some minor observations, as follows:

1. Lines 10-25: There is an issue with the formatting of the abstract, which requires indentation.
2. The reference format is incorrect, such as in the Introduction section, requiring a thorough check throughout the document.
3. The formatting of figure captions needs to be checked throughout the document.
4. Traces of modifications highlighted in yellow still remain in the text and need to be removed.

Author Response

Please see attached.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a case study evaluating the effectiveness of integrating Water-Sensitive Urban Design (WSUD) techniques with conventional grey infrastructure for flood mitigation in a small sub-catchment located in a wet tropical region of Queensland, Australia. The objective is to assess the flood mitigation performance of these systems under varying rainfall conditions.

Although the study does not introduce novel methodological approaches, it addresses an interesting and relevant topic. The primary contribution lies in applying an established methodology to a tropical urban context, which is less frequently represented in the literature. Nonetheless, the manuscript requires substantial improvements before it can be considered for publication. I therefore recommend a major revision.

Several figures lack a professional appearance and should be improved to enhance clarity and quality. Moreover, the manuscript contains numerous acronyms that are not properly defined, which hampers readability and comprehension. The methodology section is insufficiently detailed; given the multi-step modelling framework, which involves chaining different software tools and processing outputs as inputs for subsequent stages, a more transparent and structured explanation is necessary. Greater emphasis should also be placed on the visual presentation of the results.

The authors are encouraged to consider the specific comments below to improve the overall quality of the manuscript.

• Lines 17-18. “to evaluate grey and WSUD flood mitigation capabilities”. Reformulate as “to evaluate the flood mitigation capabilities of grey infrastructure and WSUD systems”.
• The acronym AEP should be defined upon first use, even if it is a commonly known term.
• Lines 22-23. The sentence “In contrast, integrating WSUD with grey infrastructure reduced peak flow by, 0% to 42%, total runoff volume reduction by 0.9% to 46% and flood extent ratio by 0.3% to 1.1%” contains grammatical issues and should be revised for clarity and correctness.
• Lines 45-46. The sentence “Traditionally, urban areas have adopted grey infrastructure, such as pipe networks, channels, inlets, gates, and walls to manage floods” is overly generic. Please provide a more precise and technically accurate definition of grey infrastructure for stormwater management.
• Lines 48-59. The current narrative appears to overly criticise grey infrastructure while overly praising nature-based solutions. It is important to acknowledge that while WSUD and green infrastructure have considerable benefits, they are often not sufficient as standalone solutions, particularly under extreme rainfall conditions. These systems typically perform best when used in combination with grey infrastructure. Please avoid conveying the message that nature-based solutions are a universal remedy; their effectiveness must be critically assessed and contextualised.
• Line 60. Provide some examples of Water-sensitive urban design (WSUD) techniques.
• Figure 1. This figure lacks a professional layout. Some items included in the legend are not visible in the figure itself. Consider improving the visual clarity and consistency of the figure. Including geographic coordinates would also enhance its utility. Regarding the Hobo sensor, clarify the terminology, for instance, specify “pressure transducer (HOBO) sensor” and indicate whether HOBO is the manufacturer. If possible, also include a representation of the artificial drainage network within the figure.
• Section 2.1. Is there a specific reason for selecting this small sub-catchment of the Saltwater Creek catchment as the study area? Does the area contain a natural drainage network?
• Line 110. Maximum daily or monthly precipitation?
• Line 112: What exactly remained dry?
• Section 2.2.1. It would be beneficial to include a summary table listing all datasets used, along with their sources (including hyperlinks if publicly available) and spatial/temporal resolution.
• Table 1. A simpler naming convention for the rain gauges would be preferable. The current descriptions may not be meaningful to readers unfamiliar with the study area. Notably, the RESWHG.RainGagTD rain gauge appears to share the exact coordinates with the centroid of the study area.
• Figure 2. Consider using a more contrasting colour to delineate the study area, as it is currently difficult to distinguish it from the background map. Can you also increase the font size for readability, especially for the rain gauge codes? Including geographic coordinates along the figure's borders and marking the centroid of the study area would enhance clarity.
• Table 2. The unit of measure should be written as “km” (lowercase “k”).
• Lines 150-154. Please consider adding a map showing the spatial distribution of LULC in the study area, including the locations planned for WSUD implementation.
• Lines 161-162. What do these depths of 4 m, 10 m, and 30 m represent?
• Figure 3. Specify pressure transducer in the caption.
• Figure 4. Please correct the legend in the figure.
• Lines 177-190. Relate AEP values to their corresponding return periods. All acronyms used should be clearly defined within the text.
• Line 183. Was the rainfall data sourced from the Bureau of Meteorology (BOM) website? Please specify.
• Line 191. Refer explicitly to RORB as a hydrological software tool for runoff routing.
• Figure 5. Consider expanding this figure to clarify how input and output data flow through the modelling chain. It would help to specify which datasets are used at each stage, and which software tools serve as input or output within the workflow. The software sequence should be clearly illustrated, as outputs from one model are used as inputs to another.
• Section 2.3. Specify which software tools are open source and which are proprietary. Also, indicate the developers or producers of each software/platform. While this is briefly mentioned in Lines 228–229, it would be more appropriate to state this earlier in the section.
• Line 215. Figure 11?
• Line 240. Which calculations were performed in Microsoft Excel?
• Section 2.3. How the interaction between the one-dimensional and two-dimensional geometry is modelled in MIKE+? Which are the other boundary conditions used?
• Section 2.5. Why did you use the kinematic wave approximation in MIKE+? It is used for both one-dimensional and two-dimensional geometries?
• Figure 8. This figure is difficult to interpret. It is recommended to label each panel with the corresponding scenario name to aid reader comprehension.
• Please minimise the use of acronyms in this section to improve readability.
• Given the large number of acronyms used throughout the manuscript, I suggest including a nomenclature section.

Author Response

Please see attached.

Author Response File: Author Response.docx