Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in the Swa Dam, Myanmar

Round 1

Reviewer 1 Report

I really enjoyed being the reviewer of such as interesting paper related to the assessment of real catastrophic dam failure. An interesting analysis is presented, and the paper may have a positive impact within geoscience’s domain. I would recommend major revisions with the enhance the discussion and improve the overall paper’s quality.

Introduction

From my view the section must be expanded. Please refer to the papers shown below and include more references in you work regarding similar catastrophic flooding events. In its current format the authors cite only 22 past works and more works must be introduced in this section. Some highlighted works are Oroville and recent Todbrook dam failures.

Chapter 2.5.1

I would use reservoir level instead of tank level. Also, I advise you to amend here the estimated peak outflows from the spillway.

Chapter 2.5.3

A typical cross section drawing describing key points failures of the spillway (foundation) will benefit the work associated with the figure 4.

Also, a better description needed here. First collapsed from structural deterioration the spillway what is then happened in the dam embankment. Not clear the catastrophic sequence. Suggest to add more description on that.

Chapter 2.8.2

Recently I presented a paper on developing updated empirical equation from earthen dam failures. Freely available here (PDF) Predictive empirical dam breach peak outflows -A global analysis and proposed updates (researchgate.net). New proposed regression simplified model can be included in your analysis provides better and satisfactory than all the models used in your analysis and given the high uncertainty of the estimated peak flows vs the observed flows (lines 507-515 of the paper)

Chapter 4.3

Thus, to mitigate damage, we must prepare hazard maps and alter systems in advance. For example, once we found the signature of collapse during regular inspections, we must develop hazard maps and alter systems. Please add relevant reference from scientific literatures.

Moreover, even if these equations were established from databases 610 of historical failures of earthen dams, the results had no significant differences when these 611 were applied to the spillway failure case. I would not agree with this statement given the high uncertainty of the predicted flows estimated assessed by empirical equation please refer to the lines 507-515 of your work and also in the cast study of U.K Pennine reservoir presented by Tegos et al. 2022.

Discussion section must be expanded with other modelling option to reproduce a real catastrophic dam failure with the use of advanced CFD techniques, machine learning methods for estimated dam breach failures etc.

Before the resubmission a native English speaker must review carefully the new submission for checking typos form. The paper in its current form has a lot of typos and inappropriate technically expressions

Dam spillway failures recommended to be added in the introduction
Si, Y., & Qing, D. (1998). The world’s most catastrophic dam failures: the August 1975 collapse of the Banqiao and Shimantan Dams. The river dragon has come, 25-38.
Koskinas, A., Tegos, A., Tsira, P., Dimitriadis, P., Iliopoulou, T., Papanicolaou, P., ... & Williamson, T. (2019). Insights into the Oroville dam 2017 Spillway incident. Geosciences, 9(1), 37.
Heidarzadeh, M., & Feizi, S. (2022). A cascading risk model for the failure of the concrete spillway of the Toddbrook dam, England during the August 2019 flooding. International Journal of Disaster Risk Reduction, 80, 103214.
Moramarco, T., Barbetta, S., Pandolfo, C., Tarpanelli, A., Berni, N., & Morbidelli, R. (2014). Spillway collapse of the Montedoglio Dam on the Tiber River, Central Italy: data collection and event analysis. Journal of Hydrologic Engineering, 19(6), 1264-1270.
Kojima, H., Kohgo, Y., Shimada, K., Shoda, D., Suzuki, H., & Saito, H. (2020). Numerical modeling of flood flow after small earthen dam failure: a case study from the 2011 Tohoku earthquake. Paddy and Water Environment, 18(2), 431-442.
Foster, M., Fell, R., & Spannagle, M. (2000). The statistics of embankment dam failures and accidents. Canadian Geotechnical Journal, 37(5), 1000-1024.

Author Response

Authors’ Responses to Reviewers’ comments

Manuscript ID: water-2221105

Title:  Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

Authors: Pa Pa Shwe Sin Kyaw *, Taro Uchida

The authors thank the editor for the consideration. The comments specified by the reviewers were addressed and reassessed in the revised manuscript. The changes-tracked version of revised manuscript is enclosed as well. We hope the revised manuscript could be accepted for publication.

Response to Reviewer 1:

I really enjoyed being the reviewer of such as interesting paper related to the assessment of real catastrophic dam failure. An interesting analysis is presented, and the paper may have a positive impact within geoscience’s domain. I would recommend major revisions with the enhance the discussion and improve the overall paper’s quality.

Re: The authors thank the reviewer for the comments. We have revised the manuscript carefully as far as we could according to your suggestions. Please see the details in the changes-tracked version of revised manuscript as attached and the itemized response is listed below:

 

Introduction

From my view the section must be expanded. Please refer to the papers shown below and include more references in you work regarding similar catastrophic flooding events. In its current format the authors cite only 22 past works and more works must be introduced in this section. Some highlighted works are Oroville and recent Todbrook dam failures.

Re: The authors thank the reviewer for the comments and the suggestions. We have expanded the introduction section. We have already referred the papers you suggested and 29 additional references including the suggested papers (Oroville dam spillway failure and Toddbrook dam failures) are added in this paper. Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

Chapter 2.5.1

I would use reservoir level instead of tank level. Also, I advise you to amend here the estimated peak outflows from the spillway.

Re: Thank you for your advice. We changed to the reservoir level (In line 180 and in Figure 3). The estimated outflows are supplemented in line 177 ~ 182. Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Chapter 2.5.3

A typical cross section drawing describing key points failures of the spillway (foundation) will benefit the work associated with the figure 4.

Also, a better description needed here. First collapsed from structural deterioration the spillway what is then happened in the dam embankment. Not clear the catastrophic sequence. Suggest to add more description on that.

Re: Thank you for your suggestion. The typical cross section of the spillway is added as Figure 5 with failure section highlighted. Chapter 2.5.3 is enhanced with more description (In line 226 ~ 244). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

Chapter 2.8.2

Recently I presented a paper on developing updated empirical equation from earthen dam failures. Freely available here (PDF) Predictive empirical dam breach peak outflows -A global analysis and proposed updates (researchgate.net). New proposed regression simplified model can be included in your analysis provides better and satisfactory than all the models used in your analysis and given the high uncertainty of the estimated peak flows vs the observed flows (lines 507-515 of the paper)

Re: Thank you for your recommended paper. We included the new proposed model from your paper in the calculation (In line 409 and 537). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

Chapter 4.3

Thus, to mitigate damage, we must prepare hazard maps and alter systems in advance. For example, once we found the signature of collapse during regular inspections, we must develop hazard maps and alter systems. Please add relevant reference from scientific literatures.

Re: Thank you for your comments. We added the relevant reference for preparing hazard maps (In line 701~702). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Moreover, even if these equations were established from databases 610 of historical failures of earthen dams, the results had no significant differences when these 611 were applied to the spillway failure case. I would not agree with this statement given the high uncertainty of the predicted flows estimated assessed by empirical equation please refer to the lines 507-515 of your work and also in the cast study of U.K Pennine reservoir presented by Tegos et al. 2022.

Re: Thank you for your comments. We modified the statement according to your comments (In line 703~704). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Discussion section must be expanded with other modelling option to reproduce a real catastrophic dam failure with the use of advanced CFD techniques, machine learning methods for estimated dam breach failures etc.

Re: Thank you for your suggestion. We modified the discussion section as far as we can (In line 625 ~ 710). We also added the use of the advanced CFD techniques and machine learning methods in conclusion section (In line 742 ~752). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Dam spillway failures recommended to be added in the introduction.

Si, Y., & Qing, D. (1998). The world’s most catastrophic dam failures: the August 1975 collapse of the Banqiao and Shimantan Dams. The river dragon has come, 25-38.
Koskinas, A., Tegos, A., Tsira, P., Dimitriadis, P., Iliopoulou, T., Papanicolaou, P., ... & Williamson, T. (2019). Insights into the Oroville dam 2017 Spillway incident. Geosciences, 9(1), 37.
Heidarzadeh, M., & Feizi, S. (2022). A cascading risk model for the failure of the concrete spillway of the Toddbrook dam, England during the August 2019 flooding. International Journal of Disaster Risk Reduction, 80, 103214.

Moramarco, T., Barbetta, S., Pandolfo, C., Tarpanelli, A., Berni, N., & Morbidelli, R. (2014). Spillway collapse of the Montedoglio Dam on the Tiber River, Central Italy: data collection and event analysis. Journal of Hydrologic Engineering, 19(6), 1264-1270.

Kojima, H., Kohgo, Y., Shimada, K., Shoda, D., Suzuki, H., & Saito, H. (2020). Numerical modeling of flood flow after small earthen dam failure: a case study from the 2011 Tohoku earthquake. Paddy and Water Environment, 18(2), 431-442.

Foster, M., Fell, R., & Spannagle, M. (2000). The statistics of embankment dam failures and accidents. Canadian Geotechnical Journal, 37(5), 1000-1024.

 

Re: Thank you for your recommended papers. We included them in the paper as far as we could. Kojima et al. 2020 and Foster et al. 2000  can’t be included in the section because they are not in the scope of this paper. Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Author Response File: Author Response.docx

Reviewer 2 Report

The article deals with the fascinating topic of dam break. However, the authors have not sufficiently documented the event, especially the condition of the earth dam before and after the event not adequately shown. The earth dam is constructed from various materials, the properties of which are not even mentioned in the article. A photo of the barrier after the collapse shows that the dam was probably upgraded in the past. Also, damage to the spillway is not presented.

The description of the event is also poorly presented; namely, there are no witness statements of the event. A realistic scenario of the collapse of most of the embankments is the phenomenon of increased water filtration through the dam, accompanied by erosion of the material. In the next stage, the dam collapses due to internal erosion, and the dam's crown collapses. In the final stage, the water overflows the dam, and in a very short time, the dam is destroyed due to surface erosion.

 

Even the corresponding hydraulic calculation with water balance analysis is not done. However, volumes of water released are very well measured thanks to measurements of the flow of water levels in the reservoir during the event. Although the water flows are measured, only values are captured in one-hour increments, which is too short a step considering the dynamics of the event. In the meantime, the flows could have been much higher.

Author Response

Authors’ Responses to Reviewers’ comments

Manuscript ID: water-2221105

Title:  Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

Authors: Pa Pa Shwe Sin Kyaw *, Taro Uchida

The authors thank the editor for the consideration. The comments specified by the reviewers were addressed and reassessed in the revised manuscript. The changes-tracked version of revised manuscript is enclosed as well. We hope the revised manuscript could be accepted for publication.

Response to Reviewer 2:

The article deals with the fascinating topic of dam break. However, the authors have not sufficiently documented the event, especially the condition of the earth dam before and after the event not adequately shown.

Re: The authors thank the reviewer for the comments. We have revised the manuscript carefully according to your suggestions. Please see the details in the changes-tracked version of revised manuscript as attached and the itemized responses are described below:

 

The earth dam is constructed from various materials, the properties of which are not even mentioned in the article. A photo of the barrier after the collapse shows that the dam was probably upgraded in the past. Also, damage to the spillway is not presented.

Re: Thank you for your advice. The properties of the dam filling material used have mentioned in the section 2.3 according to your suggestion. (In line 131~144). The Swa Dam is completed its construction in 2000 and no significant upgrades are performed since then (based on the information from IWUMD). The damages to the spillway are mentioned as far as we could in section 2.5.3 (In line 229~244). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

The description of the event is also poorly presented; namely, there are no witness statements of the event. A realistic scenario of the collapse of most of the embankments is the phenomenon of increased water filtration through the dam, accompanied by erosion of the material. In the next stage, the dam collapses due to internal erosion, and the dam's crown collapses. In the final stage, the water overflows the dam, and in a very short time, the dam is destroyed due to surface erosion.

Re: Thank you for your comments. The description of the event has modified in section 2.5.2 with new relevant Figure according to your suggestion. (In line 193~209). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

 Even the corresponding hydraulic calculation with water balance analysis is not done. However, volumes of water released are very well measured thanks to measurements of the flow of water levels in the reservoir during the event. Although the water flows are measured, only values are captured in one-hour increments, which is too short a step considering the dynamics of the event. In the meantime, the flows could have been much higher.

Re: Thank you for your advice. We have already included the calculation of the water volume change with time using reservoir water balancing (In line 296 ~297). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript). We confused what is the corresponding hydraulic calculation with water balance analysis. We would like more detailed suggestion for this comment. Thank you for your kind support.

Author Response File: Author Response.docx

Reviewer 3 Report

Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

 

Present study aims to assess the Swa Dam spillway failure case, to determine the process of spillway breaching and failure mechanisms and the effectiveness of spillways to the breach. This study also aims to clarify the similarities and differences between the spillway breaching event in the Swa Dam and ordinal dam breach events, compare previous empirical relationships, and obtain lessons to be learned from this failure case for future risk mitigation of dam failure cases in Myanmar.

The MS could be of interest to Innovative Hydraulic Structure Solutions. I believe that with some corrections in this MS is needed some more revisions. Here below some specific

comments are provided, but the list could be longer.

 Introduction is not upto the mark. Objectives of the present study are not clear. Language is bit confusing so kindly follow it up as paper requirement. Also, in this section the Authors should emphasize somewhere the importance of this study from the point of view of irrigation structures.

 Coming to the performance evaluation, the authors should include the cumulative frequency of absolute relative errors for all equations for better comparison between the performances of equations.

 What is Purity of collected data? How authors will say, quality of used data is good or average. This point can be beneficial for new readers.

 Authors can introduce sensitivity analysis for the most influencing parameters.

 Some important items are not mentioned and evaluated, e.g. the various notations used, detailed illustration needful for the case study, and so on. Please make corrections accordingly.

 Use same font size and style in all figures.

 Discussion part is bit long because of some repetition. Authors must check this section

and remove some unnecessary things from this section.

 Conclusion should be confined and easy to understand. The applications this study should be highlighted as per Journal’s point of view.

Most important, some important and latest literature is missing from the manuscript. Several recently published research papers available in this research area are listed below. Authors must introduce them in the revised MS, these papers can be very useful for the readers.

Overall, the MS could be of interest to the Journal readership.

 Aldrees et al. (2022). The effect of rough rigid apron on scour downstream of sluice gates. Water, 14(14), 2223.

 Sharma et al. (2022). Experimental observation of turbulent structure at region surrounding the mid-channel braid bar. Marine Georesources & Geotechnology, 40(4), 448-461.

Author Response

Authors’ Responses to Reviewers’ comments

Manuscript ID: water-2221105

Title:  Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

Authors: Pa Pa Shwe Sin Kyaw *, Taro Uchida

The authors thank the editor for the consideration. The comments specified by the reviewers were addressed and reassessed in the revised manuscript. The changes-tracked version of revised manuscript is enclosed as well. We hope the revised manuscript could be accepted for publication.

Response to Reviewer 3:

Present study aims to assess the Swa Dam spillway failure case, to determine the process of spillway breaching and failure mechanisms and the effectiveness of spillways to the breach. This study also aims to clarify the similarities and differences between the spillway breaching event in the Swa Dam and ordinal dam breach events, compare previous empirical relationships, and obtain lessons to be learned from this failure case for future risk mitigation of dam failure cases in Myanmar.

The MS could be of interest to Innovative Hydraulic Structure Solutions. I believe that with some corrections in this MS is needed some more revisions. Here below some specific comments are provided, but the list could be longer.

Re: The authors thank the reviewer for the comments. We have revised the manuscript carefully according to your suggestions. Please see the details in the changes-tracked version of revised manuscript as attached and the itemized responses are described below:

 

• Introduction is not up to the mark. Objectives of the present study are not clear. Language is bit confusing so kindly follow it up as paper requirement. Also, in this section the Authors should emphasize somewhere the importance of this study from the point of view of irrigation structures.

Re: Thank you for your comments. The introduction section is upgraded with more references and the importance of this study from the structure point of view (the importance of spillway structure in mitigation of disaster) is also described accordingly (In line 61~64). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

• Coming to the performance evaluation, the authors should include the cumulative frequency of absolute relative errors for all equations for better comparison between the performances of equations.

Re: Thank you for your suggestion. The relative error for each equation is calculated for individual breach parameter and we performed the performance evaluation in section 3.2.1, 3.2.2 and 3.2.3 with the relevant figures. Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

• What is Purity of collected data? How authors will say, quality of used data is good or average. This point can be beneficial for new readers.

Re: Thank you for your question. Generally, the purity of the collected data is difficult to judge precisely. All the field survey data, dam and spillway data, and water level records used in this study are collected by IWUMD, my department, and we tried our best to get good quality data. The satellite data have their accuracy description in their relevant websites. Please see the details in the revised manuscript for the details of data description.

 

• Authors can introduce sensitivity analysis for the most influencing parameters.

Re: Thank you for your suggestion. The sensitivity analysis still cannot perform in this study yet. It will be performed in our next study with other analysis.

 

• Some important items are not mentioned and evaluated, e.g. the various notations used, detailed illustration needful for the case study, and so on. Please make corrections accordingly.
• Use same font size and style in all figures.

Re: Thank you for your comments. The description of the event has modified in section 2.5.2 with new relevant Figure according to your suggestion. (In line 193~209). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

• Discussion part is bit long because of some repetition. Authors must check this section and remove some unnecessary things from this section.

Re: Thank you for your comments. We modified the discussion section as far as we can (In line 625 ~ 710). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

• Conclusion should be confined and easy to understand. The applications this study should be highlighted as per Journal’s point of view.

Re: Thank you for your comments. We modified the conclusion section as far as we could according to your suggestion. (In line 712~752). Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

 

Most important, some important and latest literature is missing from the manuscript. Several recently published research papers available in this research area are listed below. Authors must introduce them in the revised MS, these papers can be very useful for the readers. Overall, the MS could be of interest to the Journal readership.

• Aldrees et al. (2022). The effect of rough rigid apron on scour downstream of sluice gates. Water, 14(14), 2223.
• Sharma et al. (2022). Experimental observation of turbulent structure at region surrounding the mid-channel braid bar. Marine Georesources & Geotechnology, 40(4), 448-461.

Re: Thank you for your recommended papers. We included them in the paper as far as we could. However, the papers you mentioned above can’t be included in the section because they are not in the scope of this paper. Please see the details in the revised manuscript for the details (they are highlighted in the manuscript).

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper has now been revised substantially based on my first comments. I have only one minor comment. From my point of view given the uncertainty of the the type of failure with lack of historical real dataset from dam breaches, all the empirical models with low relative error than 0.5 can be describe a dam failure thoroughly. I, therefore, would revise the phrase 

From the empirical equations applied in this study, only Froehlich’s equations and Xu and Zhang 2009‘s equations could distinguish between failure mechanisms as “Froehlich’s equations and Xu and Zhang 2009‘s equations exhibits the highest among the empirical formulas, however considering the high uncertainty of the breach phenomenon and the lack of real-world sample to calibrate the models, all models with low absolute errors (i.e lower than 0.5) set out above are recommended for further application.

Author Response

Authors’ Responses to Reviewers’ comments

Manuscript ID: water-2221105

Title:  Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

Authors: Pa Pa Shwe Sin Kyaw *, Taro Uchida

The authors thank the editor for the consideration. The comments specified by the reviewers were addressed and reassessed in the revised manuscript. The changes-tracked version of revised manuscript is enclosed as well. We hope the revised manuscript could be accepted for publication.

Response to Reviewer 1:

The paper has now been revised substantially based on my first comments. I have only one minor comment.

Re: The authors thank the reviewer for the comments. We have revised the manuscript again carefully according to your suggestions. Please see the details in the changes-tracked version of revised manuscript as attached.

 

From my point of view given the uncertainty of the type of failure with lack of historical real dataset from dam breaches, all the empirical models with low relative error than 0.5 can be describe a dam failure thoroughly. I, therefore, would revise the phrase.

From the empirical equations applied in this study, only Froehlich’s equations and Xu and Zhang 2009‘s equations could distinguish between failure mechanisms as “Froehlich’s equations and Xu and Zhang 2009‘s equations exhibits the highest among the empirical formulas, however considering the high uncertainty of the breach phenomenon and the lack of real-world sample to calibrate the models, all models with low absolute errors (i.e lower than 0.5) set out above are recommended for further application.

Re: The authors thank the reviewer for the suggestions. We have added your suggestions to the phrase you mentioned above. Please see the details in the revised manuscript for the details (Line 867- 872).

Author Response File: Author Response.docx

Reviewer 3 Report

Revised manuscript may be accepted for publication.

Author Response

Authors’ Responses to Reviewers’ comments

Manuscript ID: water-2221105

Title:  Assessment of the Breaching Event, Breach Parameters and Failure Mechanisms of the Spillway Collapse in Swa Dam, Myanmar

Authors: Pa Pa Shwe Sin Kyaw *, Taro Uchida

The authors thank the editor for the consideration. The comments specified by the reviewers were addressed and reassessed in the revised manuscript. The changes-tracked version of revised manuscript is enclosed as well. We hope the revised manuscript could be accepted for publication.

Response to Reviewer 3:

Revised manuscript may be accepted for publication.

Re: The authors thank the reviewer very much for the comment. We thankfully attached the revised manuscript for round 2. Please see the details in the changes-tracked version of revised manuscript as attached.

Author Response File: Author Response.docx