Unraveling Debris-Enhanced Local Scour Patterns around Non-Cylindrical Bridge Piers: Experimental Insights and Innovative Modeling

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is an extensive and intensive investigation of debris impact on scouring around piers.

The study address an important problem in major engineering infrastructure sustainability. I would support its publication.

In comparison with other published materials, this article studies an extensive list of piers and debris geometries.

It does seem that the debris investigated in the paper are stationary placed. It doesn’t move with the flow. The dynamics of debris is neglected. The implication of this experimental design need to be discussed.

Conclusions are consistent with the evidence but without inclusion of debris’ dynamics, the study can only represent a first step to address the main question.

In addition, references are appropriate.

Comments on the Quality of English Language

It is fine.

Author Response

We are grateful for the reviewer's informative comments and helpful input on our study on the influence of debris on scouring surrounding piers. We'd want to respond to each of the reviewer's concerns:
1- Extensive inquiry: We are glad that the reviewer recognizes the thoroughness and intensity of our inquiry. We have made great efforts to investigate the impact of various debris and pier shapes on scouring.
2- Implications for Engineering Infrastructure Sustainability: We appreciate the reviewer's acknowledgement of the significance of our work in the context of significant engineering infrastructure sustainability. This is a critical topic, and we are devoted to assisting in its understanding and solutions.

3- The reviewer accurately notes that the debris in the research we conducted is stationary, and we weren't taking into account its dynamic behavior within reaction to flow. We recognize this issue, and it is something we plan to address in future studies. The ramifications of this experimental design are substantial, and we appreciate the reviewer's emphasis on this point.

4- Debris Dynamics: We absolutely agree with the reviewer that debris dynamics are an important factor to address. While our findings are consistent with the facts, we acknowledge that more study on debris dynamics is required to completely address the core topic. We intend to investigate this aspect more in our future work.

5- acceptable References: We are delighted that the reviewer thought our references were acceptable. We make every effort to give a thorough and well-referenced perspective for our findings.

Finally, we appreciate the reviewer's encouraging words as well as constructive feedback. We will consider these recommendations and incorporate them into our continuing study to broaden and deepen our findings, particularly into the dynamic behavior of debris. Many thanks for your insightful comments.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

Find the comments below:

1.      Figure 1 has 3 different images so it’s better to mention it as figure 1. (a), (b) & (c) with label naming.

2.      Figure 10 overlaps with the axis title. Please redrawn.

3.      The paper introduces a novel method for evaluating the effect of debris accumulation on local scour depth at bridge piers, proposing the concept of a "debris factor" to replace current methods. However, it did not address the limitations of existing approaches for scour assessment, such as the approach by Lagasse et al. (2010). Please look into the matter.

4.      The proposed method for evaluating local scour depth at bridge piers due to debris accumulation is applicable only to the scenario of debris located just under the flow-free surface. It may not account for submerged debris or debris on the stream bed with high velocity. Provide necessary justification.

5.      The paper does not mention any limitations or potential uncertainties in the measurements or data analysis. Please incorporate the necessary.

6.      Further investigation is needed to explore debris accumulation's effect on bridge piers' stability in different flow conditions and sediment characteristics.

7.      Practical implementation on the site of this research should have been mentioned properly in the abstract and conclusion section.

8.      The paper evaluates the influence of relative coarseness and flow shallowness on scour depth, providing insights into the governing parameters of pier scour geometry. Still, there is room for improvement in validating the new equation with other methods available.

 

9.      Check the English throughout the manuscript.

Comments on the Quality of English Language

Moderate editing of English language is required.

Author Response

3. Addressing Existing methodologies: We acknowledge the reviewer's point about ignoring the limits that currently scour assessment methodologies. In our publication, we will include a section that examines the limits and uncertainties of current approaches, including the methodology developed by Lagasse et al. (2010).
4. We appreciate the reviewer's feedback and would like to emphasize that we have previously studied the case of submerged debris on the stream bed, and the suggested solution takes this into account. We regret any misunderstanding caused by the publication. In our work, the approach for calculating local scour depth owing to debris buildup takes into consideration a variety of circumstances, including debris immediately beneath the flow-free surface with a relative depth (T/Y) equal to 0.25  as well as partial submerged with (T/Y=0.5) and fully submerged on the stream bed with (T/Y=1). Our research is intended to offer a full knowledge of the consequences of debris under diverse settings, and we have taken these possibilities into account.
5. Mentioning Limitations and Uncertainties: We agree with the reviewer's advice to add in our manuscript a section that describes the limitations and probable uncertainties in the measurements and data analysis. This will make our study more transparent.
6. Further Research: The reviewer's point about the need for more research into the impact of debris deposition on bridge pier stability under diverse flow conditions and sediment qualities is well received. In our limits, we will emphasize this as a possible topic for further study.

7. Practical Implementation: We agree with the reviewer's point on the need to mention practical implementation on the study site in the abstract and conclusion sections. These sections will be expanded to incorporate information regarding the practical implications of our results.

8. Validation of the New Equation: The reviewer emphasizes the importance of further validating our new equation using various approaches. This proposal is appreciated, and we will note the possibility for improvement in verifying our equation in the study. However, as we mentioned in the research, there are very few studies that consider the effect of floating debris on the non-cylindrical pier shape. Also, most of the rest of the research considered single-log debris, while this equation works well when the debris accumulates and extends toward the stream bed, as happened in real scenarios.
We are grateful for the detailed feedback, and we will incorporate these recommendations into our research to enhance its clarity, scope, and practical relevance. Your insights are invaluable, and we thank you for your time and expertise.

Reviewer 3 Report

Comments and Suggestions for Authors

Unraveling Debris-Enhanced Local Scour Patterns around Non Cylindrical Bridge Piers: Experimental Insights and Innovative  Modeling

1)     Abstract fails to present the motivations and research gap on current analysis. Revise it.

2)     Literature survey is poor. Include some recent research on current topic.

3)     How range of Reynolds number is considered (line 219)?

4)     Explanation of figure 2 is not complete.

5)     How Hydraulic Factors and Parameters influenced the stream water level?

6)     Eqs. (1-2) need proper references.

7)     The relation for shape factor should be justified in view of eq. (3).

8)     Conclusion section is too long. Summarize it comprehensively.

Comments on the Quality of English Language

Minor typo errors should be corrected. 

Author Response

Dear Reviewer,
We truly appreciate the reviewers' helpful remarks and ideas for improving our article.
To begin, we recognize the need to strengthen the abstract by offering more specific motives and addressing the research gap. We will try to improve this section so that it provides a full understanding of the context and importance of our study. Second, the reviewer accurately points out that our literature study should be more comprehensive, especially in terms of recent research on the issue. We appreciate your comments and will include the latest research to increase the depth and relevancy of our literature review.
Regarding the range of Reynolds numbers considered in the study, we focused on varying the pier and debris shape with different submergences from 3 to 6 to 12 cm from the free surface and checking the effect of the same flow rates, sand particle uniformity, Froud and Reynold numbers, etc. on the different piers and debris shapes. However, we admit that further study needs to consider the differences in important parameters like the Reynolds number on the scouring mechanism.
Figure 2's description will be changed to ensure its completeness and to offer a clearer comprehension of the material presented in the figure.
To guarantee transparency, we already added the corrected references for Eqs. (1-2), which is  B. W. Melville and Y.-M. Chiew, “Time scale for local scour at bridge piers,” J. Hydraul. Eng., vol. 125, no. 1, pp. 59–65, 1999.
To improve the clarity of our approach, we shall provide the reasoning for the shape factor relation in light of Eq. (3) in greater detail.
Finally, we recognize the reviewer's concern about the excessive length of the concluding section. We will work on summarizing this section more thoroughly to communicate the important results and implications more concisely.

We appreciate the reviewer's insightful remarks and suggestions, which will help to enhance the quality and clarity of our article. Your feedback is extremely useful to us.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for attending all comments.

Reviewer 3 Report

Comments and Suggestions for Authors

The suggested changes have been implemented now. 

Comments on the Quality of English Language

Ok