Review Reports - Assessment of Object-Level Flood Impact Considering Pump Station Operations in Coastal Urban Areas

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article “Assessment of Object-Level Flood Impact Considering Pump Station Operations in Coastal Urban Areas” has been reviewed.

It is a paper whose objective is to develop a high-resolution urban flood modeling framework that integrates mobile pump station operations with impact assessment, leveraging parallelized high-performance computing and multi-source geographic information.

This article addresses a current and relevant issue and is overall quite well written. Below are some recommendations that could help improve it.

Sections 2 and 3 should be combined. There is no need to present a general overview of a model in one section and then present it again within the framework of a case study. I suggest that the authors adopt the standard approach by creating a Section 2 entitled “Data and Methods.” In this section, they can include several subsections to describe their study area, data, models, model performance criteria, etc.

Section 4, in which the authors present their results, should simply be entitled “Results and Discussion.” They may discuss their results immediately after presenting them, or create two subsections — one for the results and another for the discussion.

I recommend that the authors thoroughly discuss their results by comparing them (similarities and differences) with those of other studies. What currently serves as the discussion in this paper needs to be substantially strengthened and should not be combined with the conclusion. The discussion section of a scientific paper cannot be merged with the conclusion.

Author Response

Thank you very much for taking the time to review this manuscript. These positive and constructive comments are all valuable and helpful for revising and improving our manuscript, as well as the important guiding significance to our researches. Please find the detailed responses below and the corresponding revisions in the re-submitted files.

Comments 1: Sections 2 and 3 should be combined. There is no need to present a general overview of a model in one section and then present it again within the framework of a case study. I suggest that the authors adopt the standard approach by creating a Section 2 entitled “Data and Methods.” In this section, they can include several subsections to describe their study area, data, models, model performance criteria, etc.

Response 1: We sincerely appreciate this constructive suggestion. We agree that combining these sections improves clarity and follows standard scientific writing conventions. We have restructured the manuscript by merging the original Sections 2 and 3 into a new Section 2 entitled "Materials and Methods," which now includes subsections for study area (2.1), numerical methods (2.2), experiment design and scenarios (2.3), and model evaluation metrics (2.4). (Please refer to lines 102-266, as in the clean version of manuscript).

Comments 2: Section 4, in which the authors present their results, should simply be entitled “Results and Discussion.” They may discuss their results immediately after presenting them, or create two subsections — one for the results and another for the discussion.

Response 2: Thank you for this helpful recommendation. We have restructured the manuscript to better integrate results with their interpretation. We have retitled Section 3 as "Results" and created a new Section 4 entitled "Discussion," which provides comprehensive analysis and comparison with existing literature. Section 3 "Results" (pages 9-18, lines 270-426) now presents the hydrodynamic performance and validation, object-level impact assessment, and effectiveness of mobile pumping stations. Section 4 "Discussion" (pages 16-19, lines 428-546) has been added to provide in-depth analysis including model performance in coastal urban areas (Section 4.1), sensitivity to pumping rates (Section 4.2), and framework advantages and limitations (Section 4.3).

Comments 3: I recommend that the authors thoroughly discuss their results by comparing them (similarities and differences) with those of other studies. What currently serves as the discussion in this paper needs to be substantially strengthened and should not be combined with the conclusion. The discussion section of a scientific paper cannot be merged with the conclusion.

Response 3: We have significantly expanded and restructured the discussion to provide comprehensive comparison with existing literature and to critically analyze our findings. The discussion is now presented as a separate section (Section 4) distinct from the conclusions (Section 5). A new Section 4 "Discussion" (as mentioned in Comment 2) has been created with three subsections: (1) Model performance in coastal urban areas (4.1) compares our validation metrics with similar high-resolution studies and discusses compound flooding dynamics in relation to Yuan et al. [28] and urban vulnerability patterns consistent with Kreimer et al. [29]; (2) Sensitivity to pumping rates (4.2) discusses threshold effects consistent with findings from Yazdi et al. [30] and Li et al. [31]; (3) Framework advantages and limitations (4.3) critically evaluates computational innovations, methodological contributions, and identifies specific limitations and future research directions. Section 5 "Conclusions" (lines 547-580) now exclusively presents concise findings without mixing discussion elements.

New Added Ref:

Yuan, J.; Zheng, F.; Duan, H.-F.; Deng, Z.; Kapelan, Z.; Savic, D.; Shao, T.; Huang, W.-M.; Zhao, T.; Chen, X. Numerical modelling and quantification of coastal urban compound flooding. Journal of Hydrology 2024, 630, 130716.
Kreimer, A.; Arnold, M.; Carlin, A. Building safer cities: the future of disaster risk; World Bank: 2003.
Yazdi, J.; Choi, H.; Kim, J. A methodology for optimal operation of pumping stations in urban drainage systems. Journal of hydro-environment research 2016, 11, 101-112.
Li, X.; Hou, J.; Chai, J.; Du, Y.e.; Han, H.; Fan, C.; Qiao, M. Multisurrogate assisted evolutionary algorithm–based optimal operation of drainage facilities in urban storm drainage systems for flood mitigation. Journal of Hydrologic Engineering 2022, 27, 04022025.
Dong, L.-Y.; Shuai, Z.-J.; Yu, T.; Jian, J.; Guo, Y.-B.; Li, W.-Y. A multi-field coupling simulation model for the centrifugal pump system. Mechanics & Industry 2023, 24, 9.
Specklin, M. On the assessment of immersed boundary methods for fluid-structure interaction modelling: Application to waste water pumps design and the inherent clogging issues. Dublin City University, 2018.

Reviewer 2 Report

Comments and Suggestions for Authors

The primary objective of the reviewed article was to develop a high-performance integrated hydrodynamic modeling system, pumping system model, and flood impact assessment model to assess facility-level exposure and quantify the benefits of pumping. The article is well-written, but several aspects require improvement. The abstract should include information on how the proposed study differs from similar studies conducted in other research areas. The introductory section is well-written. The authors utilized the available bibliography to contextualize the analyzed topic in the context of other works. This section requires no improvement. The methodological section contains the most important information regarding the models used. However, I suggest adding general information about the models used – what their purpose is, what their limitations are, what they are based on, and please provide a justification for their selection. Figure 1 should be enlarged or its resolution changed. The description of the study area lacks the characteristics of the hydrogeological conditions that influence the performance of the model. The remaining drawings do not require improvement because they are in good resolution. The results section does not require correction. The text is written correctly. However, the discussion and conclusions section requires changes. Currently, it is a brief summary of the most important results of the work. There is no reference to other similar studies. There is no comparison of the results obtained for this specific research area with other models. There is no discussion of the effectiveness of the proposed model. Please add a few sentences of summary, including plans for further development of the method. The bibliography used raises no objections. The text is written in correct language.

Author Response

Comments 1: The abstract should include information on how the proposed study differs from similar studies conducted in other research areas.

Response 1: Thank you for this valuable suggestion. We have revised the abstract to clearly articulate the novelty and advantages of our framework compared to existing approaches. The abstract has been revised to emphasize key innovations: "Mobile pumping stations offer a practical and cost-effective solution for flood protection in low-lying, densely populated coastal areas. However, previous studies typically used simplified methods to represent pump stations, and few have integrated pump operations into high-resolution simulations of multi-source urban flooding" (lines 18-21).

Comments 2: The introductory section is well-written. The authors utilized the available bibliography to contextualize the analyzed topic in the context of other works. This section requires no improvement.

Response 2: Thank you for the positive comment.

Comments 3: The methodological section contains the most important information regarding the models used. However, I suggest adding general information about the models used – what their purpose is, what their limitations are, what they are based on, and please provide a justification for their selection.

Response 3: We appreciate this constructive comment. We have enhanced the methodology section by adding comprehensive descriptions of each model component, including their theoretical foundations, purposes, and justifications for selection. Section 2.2 "Numerical Methods" has been expanded with introductory context: "HiPIMS is used to simulate flood dynamics and has been widely applied to urban flooding under compound drivers (e.g., rainfall, tidal levels, typhoons), supporting applications in estuarine and coastal cities"(lines 139-141); "To capture pump effects during the event, the PSM is fully coupled with HiPIMS via a mass-conservative source–sink scheme. This internal source coupling directly resolves localized drawdown and flow redistribution. " (lines 179-181); " The Flood Impact Model maps hydrodynamic outputs to object-level exposure using depth thresholds and stability/damage functions."(lines 200-201).

Additionally, Section 4.3 "Framework Advantages and Limitations" (lines 511-546) provides critical evaluation of model capabilities and explicitly acknowledges limitations including hypothetical pump parameters, regional damage function applicability, and parameter uncertainties (lines 529-538).

Comments 4: Figure 1 should be enlarged or its resolution changed.

Response 4: Thank you for pointing this out. We have improved the resolution of Figure 1 (refer to Figure 2 in the revised manuscript).

Comments 5: The description of the study area lacks the characteristics of the hydrogeological conditions that influence the performance of the model.

Response 5: We appreciate this insightful comment. We have added detailed hydrogeological characteristics that are crucial for understanding flood behavior and model parameterization. Section 2.1 "Study Area" has been expanded to include hydrogeological context: "The domain exhibits hydrogeological characteristics that influence flood behavior. Elevation drops sharply from over 300 m in mountainous areas to below 5 m on the coastal plain, promoting rapid runoff concentration. The old town in the city has a shallow groundwater table that restricts subsurface drainage. Tidal influence extends upstream and interacts with channel outfalls, and existing drainage infrastructure provides limited capacity during extreme events" (lines 120-125).

Comments 6: The remaining drawings do not require improvement because they are in good resolution.

Response 6: Thank you for the positive comment.

Comments 7: The results section does not require correction. The text is written correctly. However, the discussion and conclusions section require changes. Currently, it is a brief summary of the most important results of the work. There is no reference to other similar studies. There is no comparison of the results obtained for this specific research area with other models. There is no discussion of the effectiveness of the proposed model.

Response 7: We are grateful for this positive comment and critical feedback. We have completely restructured and substantially expanded the discussion to include comprehensive comparison with existing literature, critical evaluation of model performance, and thorough analysis of the framework's effectiveness.

A new Section 4 "Discussion" has been created with three subsections: (1) Model performance in coastal urban areas (4.1, lines 429-470) compares our validation metrics with similar high-resolution studies and discusses compound flooding dynamics in relation to Yuan et al. [28] and urban vulnerability patterns consistent with Kreimer et al. [29]; (2) Sensitivity to pumping rates (4.2, lines 471-510) discusses threshold effects consistent with findings from Yazdi et al. [30] and Li et al. [31]; (3) Framework advantages and limitations (4.3, line 511-546) critically evaluates computational innovations of the proposed model, as "The HiPIMS-PSM-FIM framework advances existing approaches through computational and methodological innovations. GPU acceleration on NVIDIA Tesla K80 achieves runtime less than 50% of event duration, enabling near-real-time forecasting essential for operational emergency response rather than post-event analysis. The high spatial resolution (3 m) enables detailed urban terrain representation and object-level impact assessment, providing actionable information for targeted mitigation planning versus conventional aggregated district-scale estimates. This granularity proves particularly valuable for prioritizing emergency resources and designing localized protection measures." (lines 512-519). And also, methodological contributions, and identifies specific limitations are presented in the same subsection.

New Added Ref:

Yuan, J.; Zheng, F.; Duan, H.-F.; Deng, Z.; Kapelan, Z.; Savic, D.; Shao, T.; Huang, W.-M.; Zhao, T.; Chen, X. Numerical modelling and quantification of coastal urban compound flooding. Journal of Hydrology 2024, 630, 130716.
Kreimer, A.; Arnold, M.; Carlin, A. Building safer cities: the future of disaster risk; World Bank: 2003.
Yazdi, J.; Choi, H.; Kim, J. A methodology for optimal operation of pumping stations in urban drainage systems. Journal of hydro-environment research 2016, 11, 101-112.
Li, X.; Hou, J.; Chai, J.; Du, Y.e.; Han, H.; Fan, C.; Qiao, M. Multisurrogate assisted evolutionary algorithm–based optimal operation of drainage facilities in urban storm drainage systems for flood mitigation. Journal of Hydrologic Engineering 2022, 27, 04022025.
Dong, L.-Y.; Shuai, Z.-J.; Yu, T.; Jian, J.; Guo, Y.-B.; Li, W.-Y. A multi-field coupling simulation model for the centrifugal pump system. Mechanics & Industry 2023, 24, 9.
Specklin, M. On the assessment of immersed boundary methods for fluid-structure interaction modelling: Application to waste water pumps design and the inherent clogging issues. Dublin City University, 2018.

Comments 8: Please add a few sentences of summary, including plans for further development of the method.

Response 8: Thank you for this suggestion. We have included future research directions and methodological development plans, as “Future research directions include: (1) optimizing multi-pump configurations with coordinated schedules; (2) integrating real-time forecasting with numerical weather predictions and data assimilation; (3) evaluating long-term risk under climate change scenarios; (4) applying the framework to diverse coastal cities to assess transferability. Additionally, incorporating human behavior during floods and coupling with economic models for indirect losses would provide more comprehensive assessments. User-friendly interfaces and decision support tools would facilitate practitioner adoption for real-world applications.” (lines 539-546).

Comments 9: The bibliography used raises no objections. The text is written in correct language.

Response 9: Thank you for the positive comment.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

The manuscript regarding Assessment of pump station in coastal areas seems important and authors work showed good efforts and innovation in the subject. But it need further improvement and to submitted as per journal guidelines. From abstract to conclusion all sections are not in line with the guidelines. There is confusion in section 2 & 3, that which part is methodology. The section has been presented with Long equations and figures (additional materials can be presented in the supplementary section). Experimental methods should be clearly mentioned in materials and methods.

Please follow the guidelines of the journal.

https://www.mdpi.com/journal/water/instructions

All the section need revision and decision as under:

Reconsider after Major revisions and need to rewrite the manuscript as per journal policy and guidelines.

Author Response

Comments 1: From abstract to conclusion all sections are not in line with the guidelines.

Response 1: We sincerely appreciate your constructive comments. We have completely restructured the manuscript to follow standard scientific article formatting guidelines with clear sections. The entire manuscript structure has now been reorganized: Abstract (lines 16-35); Section 1 "Introduction" (lines 36-101); Section 2 "Materials and Methods" with subsections 2.1-2.4 (pages 3-9, lines 102-269); Section 3 "Results" with subsections 3.1-3.3 (pages 9-16, lines 270-426); Section 4 "Discussion" with subsections 4.1-4.3 (pages 16-19, lines 428-546); Section 5 "Conclusions" (pages 19-20, lines 547-580); followed by standard sections for Author Contributions, Funding, Data Availability, Conflicts of Interest, and References.

Comments 2: There is confusion in section 2 & 3, that which part is methodology. The section has been presented with Long equations and figures (additional materials can be presented in the supplementary section).

Response 2: Thank you for this suggestion. In the original submission, the mathematical formulations were described across multiple sections rather than in a single methodological locus, may leading to the unduly long analytical content. Following the reviewer's guidance in Comment 1, we have restructured the manuscript by consolidating all mathematical formulations into Section 2, which now provides a self-contained methodological foundation.

Beyond this reorganization, we have undertaken a systematic paragraph-by-paragraph review to address the specific concern about the equations and figures. Our revision strategy includes:

1) Equation minimization and control: After careful review, we retained only the essential equations required for experimental reproducibility—specifically the governing shallow water equations (Eqs. 1-3), the source term coupling method (Eq. 4), and validation metrics (Eqs. 5-6).

2) Enhanced readability through visual-textual integration: To improve clarity and readability, we have added conceptual introductions before each equation block to explain their necessity: "HiPIMS is used to simulate flood dynamics and has been widely applied to urban flooding under compound drivers (e.g., rainfall, tidal levels, typhoons), supporting applications in estuarine and coastal cities"(lines 139-141); "To capture pump effects during the event, the PSM is fully coupled with HiPIMS via a mass-conservative source–sink scheme. This internal source coupling directly resolves localized drawdown and flow redistribution. " (lines 179-181); " The Flood Impact Model maps hydrodynamic outputs to object-level exposure using depth thresholds and stability/damage functions."(lines 200-201). We also have presented parameters in the model to practical applications in Section 2.3: "The values of Manning coefficients in Eq.(3) are 0.02 for roads, plazas and parking spaces, 0.05 for buildings, 0.08 for mountain areas and green fields, 0.035 for bare grounds and water bodies" (lines 233-235). We have removed all methodological restatements from Section 3 (as Results in the revised manuscript), which now focuses exclusively on simulation outcomes and findings.

We hope this reorganization and the targeted streamlining address the reviewer’s concern while preserving the study’s main content. We are happy to make further adjustments if the reviewer identifies additional places where clarity can be improved.

Comments 3: Experimental methods should be clearly mentioned in materials and methods.

Response 3: Thank you for this important comment. We have added a dedicated subsection to explicitly describe the experimental design, including scenario configuration, pump operation strategies, and sensitivity analysis. A new Section 2.3 "Experiment Design and Scenarios" has been added, which clearly describes: (1) the baseline scenario configuration using topographical and hydrometeorological data; (2) the mitigation scenario incorporating mobile pumping station P1 with specific capacity and threshold-based activation criteria; and (3) the sensitivity analysis examining five different pumping rates while maintaining all other parameters constant (lines 225-258).

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Review Report of the paper “Assessment of Object-Level Flood Impact Considering Pump Station Operations in Coastal Urban Areas”

This paper has been revised for the second time. The comments I suggested to the authors in my previous review have been addressed.
I recommend the publication of their article.

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have corrected the manuscript in accordance with all suggested remarks. Paper can be published in a current form.