The Coupled Application of the DB-IWHR Model and the MIKE 21 Model for the Assessment of Dam Failure Risk
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIt is suggested that further research should be carried out on the popularization and application of dam-break numerical simulation proposed in the manuscript in the future.
Author Response
Comments 1:It is suggested that further research should be carried out on the popularization and application of dam-break numerical simulation proposed in the manuscript in the future.
Response 1:Thank you for recognition of the broader implications that our research may have. The application of dam failure modelling techniques is of critical importance in the realms of flood management and dam safety. As part of our ongoing research programme, we intend to conduct further investigation into these areas. It is our intention to extend the scope for which our models may be applied and to encourage their adoption by the engineering and scientific communities.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsPaper 3215043: “The coupled application of the DB-IWHR model and the MIKE 21 model for the assessment of dam failure risk”.
The paper is interesting; however, some improvements are necessary for the publication in the journal.
English is generally ok; however, it would be helpful to have English verified by a native speaker.
The principal comment on the paper is as follows. The Discussion paragraph would be expanded; this paragraph is less extensive than the conclusion. The results should be explained with values and graphs, and ​​compared (if possible) with the results of other methods, to support the conclusions;
Some specific comments:
- The VOF method would be defined when is cited;
- The material of the earth dam of the KET basin is defined as homogeneous but made up of chalk and clay. Please specify and allow the particle size composition of the clay, chalck and of the mixture clay+chalk (if possible).
- Describe approximately the stratigraphic composition of the valley's soils because they influence the roughness of the area and the infiltration and therefore the runoff;
- Describe the dam failure;
- -Are there monitoring instruments in the dam? If yes, describe (for example piezometers, inclinometers, tensiometers, rain gauges);
- How were the roughness values ​​chosen?
- Are water infiltrations into the soil considered in the model? Does infiltration depend on the constitution of the soil and the percentage of surface area covered by buildings and road pavements etc.? from Vegetation? Please explain how these quantities affect the model results.
- The term soil is more appropriate than terrain;
- Calibrate the font size scale in the figures to have better readability of the figures.
Comments for author File: Comments.pdf
English is generally ok; however, it would be helpful to have English verified by a native speaker.
Author Response
Comments 1:The VOF method would be defined when is cited;
Response 1: Thank you for the correction. We agree with this feedback and have added to it. In the previous citation we failed to provide a clear definition of the VOF method. The definition of the VOF method is now elaborated as follows: the volume of fluid (VOF) method is a computational fluid dynamics technique specifically designed to track the interfacial motion between two or more immiscible fluids. The technique is usually used in conjunction with the Navier-Stokes equations to model fluid dynamics. We have included this addition in lines 37-40 of the manuscript so that the reader can more fully understand the application and importance of the method.
Comments 2:The material of the earth dam of the KET basin is defined as homogeneous but made up of chalk and clay. Please specify and allow the particle size composition of the clay, chalck and of the mixture clay+chalk (if possible).
Response 2: Thank you for your valuable review comments.we have added detailed information on the grain size composition of the silt soil and silty clay. Based on site investigations and geotechnical test analyses, we have determined that the earth dam is a homogeneous earth dam, constructed of artificial fill, with silt soil and silty clay as the predominant lithologies. Particle analysis tests showed that the content of soil particles smaller than 0.075 mm ranged from 57.3% to 75.0% in the silt soil layer of the dam, while the content of soil particles smaller than 0.075 mm ranged from 66.8% to 82.8% in the silty clay layer. These additional particle size composition data have been incorporated into the manuscript and can be found on lines 229-236. We believe that the inclusion of this information will contribute to a more complete understanding of the material properties of the earth dams. Thank you again for your careful review and suggestions.
Comments 3:Describe approximately the stratigraphic composition of the valley's soils because they influence the roughness of the area and the infiltration and therefore the runoff;
Response 3: Thank you for your detailed review and insightful comments. We concur with the assertion that soil stratigraphic composition is a crucial factor in the modelling of surface roughness and permeability, which has a substantial influence on runoff conditions. However, the present study is concerned with the dynamics of runoff and the characteristics of flood propagation within the catchment area. The model setup includes comprehensive inputs of topography, time step and incoming water processes. At this stage, the detailed composition and infiltration properties of the soil horizons were not considered, primarily due to the focus of the current study on understanding the runoff response at the catchment scale and the limitations imposed by the availability of data. In light of the available data, a wider range of watershed parameters was selected for modelling. Furthermore, it was assumed that the impact of soil infiltration on runoff would be relatively minor over the time scales studied, particularly during extreme flood events.
We recognise that the omission of soil infiltration may have some impact on model results, particularly when simulating long time series or small scale events. In order to further refine our model, we recommend that future work incorporate soil infiltration as an important variable in the simulation. This may include the collection of more detailed soil data and coupling with more sophisticated groundwater models to more accurately simulate soil-water interactions. We believe this will enhance the predictive power of the models and provide deeper insights for watershed management.
Comments 4:Describe the dam failure;
Response 4: Thank you for your valuable feedback and we apologise .We acknowledge that the manuscript does not provide a comprehensive account of the dam failure process, which may potentially impede the reader's comprehension of the event in its entirety. To address this issue, the relevant content has been incorporated into the manuscript. The following is a detailed description of the dam failure process: As the water level continued to rise, the water pressure inside the dam body increased dramatically. Concurrently, the shear strength of the structural materials of the dam body failed to meet the requisite standards, resulting in erosion and scouring of the dam materials. This phenomenon resulted in a reduction in the stability of the dam body, which in turn led to the localised sliding of the soil and the formation of landslides. At the weak points of the dam body, the erosive action of the water flow was particularly significant, rapidly leading to the formation of an initial breach. As the breach continues to expand, it reaches a critical size at which the rapid loss of dam material triggers a significant outflow of water from the reservoir, ultimately leading to a dam failure. This section has been updated to lines 239-248 of the manuscript to provide a more comprehensive understanding of the dynamic process of dam failure. We appreciate your valuable suggestions.
Comments 5:Are there monitoring instruments in the dam? If yes, describe (for example piezometers, inclinometers, tensiometers, rain gauges);
Response 5: Thank you for your careful review and questions. Regarding whether monitoring instruments are installed on the dam, according to the information I have so far, the dam is indeed equipped with some monitoring equipment, including: flow gauges, pressure tubes, water level gauges, and outflow monitoring. We have added this section to lines 188-196 of the manuscript, and your question refers to equipment such as piezometers, inclinometers, tensiometers, and rain gauges, which are indeed common in dam monitoring, but unfortunately I have not been able to find any information in my current research on how specifically these particular pieces of equipment are equipped at dams. Possible reasons for this are that this information is not mentioned in publicly available information or is beyond the scope of data collection for this study.
Comments 6:How were the roughness values ​​chosen?
Response 6: Thank you for your valuable review comments. In order to ascertain the roughness values, I adopted the following approach, in accordance with the guidelines set forth in the hydraulic calculation manual. I conducted a comprehensive delineation of the study area, encompassing a diverse range of terrains, including rivers, residential areas, roads, and other features. For each area, the median value of each interval was selected as a representative value of roughness for that area, based on the range of roughness values provided in the manual. The objective of this strategy is to guarantee that the selected roughness values accurately reflect the hydrological characteristics of each area. This selection process is explained in detail in Section 3.2.4 of the article, with the aim of providing the reader with a comprehensive understanding of the criteria and rationale for the selection of roughness values. It is my hope that this will provide the necessary clarity and reference for the reader's understanding of roughness value selection.
Comments 7:Are water infiltrations into the soil considered in the model? Does infiltration depend on the constitution of the soil and the percentage of surface area covered by buildings and road pavements etc.? from Vegetation? Please explain how these quantities affect the model results.
Response 7: Thank you for your comprehensive review and invaluable recommendations. In response to the enquiry regarding the incorporation of water infiltration into the soil, we wish to clarify that this has not yet been directly included in the current iteration of the MIKE 21 model. As previously stated in response to your third question, the objective of this study is to examine the watershed-scale runoff response, and the limitations of data access must also be considered. Based on the available data, we elected to model watershed parameters with broader coverage. Furthermore, our modelling was predicated on the assumption that the impact of soil infiltration on runoff is relatively insignificant over the time scales prescribed by the study, particularly during extreme flood events.We are concerned about this possible limitation and will continue to explore ways to improve the model.
Comments 8:The term soil is more appropriate than terrain;
Response 8: Thank you for your valuable suggestions and thorough review of the manuscript. I have given some thought to your suggestion to replace the word 'terrain' with 'soil'. Typically, the term 'topography' is used to describe the three-dimensional structure of the land surface, including macroscopic features such as slopes and undulations, whereas 'soil' focuses on the type, characteristics and distribution of soil on the surface. In this study, our focus is on the macroscopic features of surface morphology and their influence on fluid movement, rather than on the specific properties of soil. With this in mind, we believe that the term 'topography' is more appropriate to accurately reflect the content of the study. We have therefore decided to continue to use the term 'topography' in the text. Thank you again for your comments and suggestions.
Comments 9:Calibrate the font size scale in the figures to have better readability of the figures.
Response 9: Thank you for the insightful recommendations you have offered. I have conducted a comprehensive review of the images, adjusting the font sizes where necessary to enhance clarity and legibility in the charts and tables. I am confident that these improvements will better cater to the reading habits of the readers and convey the information contained in the charts in a more effective manner. I would like to express my gratitude once more for your guidance.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsManuscript Number: Water-3215043
Title”
The coupled application of the DB-IWHR model and the MIKE 21 model for the assessment of dam failure risk”
The manuscript describes a dam-break case study utilizing the DB-IWHR and the MIKE 21 model.
The article's content is interesting, but this reviewer has suggestions for improving the manuscript.
· The introduction is brief, and there are no references to similar studies. It should also be discussed whether other authors have studied criteria of affection depending on the values of height and speed and their product, and what regulations exist that oblige this type of study.
· Authors should change the structure of the manuscript by introducing a “Materials and Methods” section describing the models used.
· A flow chart describing how the authors have developed the methodology proposed by the manuscript is much needed.
· There are no references about DB-IWHR model
· Line 89 2.2 Scrub model or 2.2 Scour Model????
· A figure showing each of the parameters used would be necessary to describe the dam break model.
· Line 94; what is zulz?
· The reviewer does not understand the expression “ulcer” to refer to the process of rupture. Is it possible that the authors mean breakage zones?
· A table with all analysed breakage data is necessary, including the addition of all calculated breakage hydrographs in Figure 3.
· Overtopping failure is predominant in dams, but the authors do not comment on possible tubification failure. This should be discussed even in the introduction, as well as if possible, a comparison of maximum flow rates of overtopping and piping failure and their difference in the propagation of the dambreak wave.
· The authors say (Line 189-190):
“From the many simulation data, it can be concluded that the higher the starting level of simulating flood, the shorter the duration of the dam failures, and the larger the maximum discharge flow.”
This sentence must be quantitatively justified by the results obtained.
· What does “grid encrypted” mean? Adjusted?
· In Figure 8, the legend values do not match Table 1.
· The authors do not analyze propagation times. This variable is crucial for the management and planning of a potential emergency. The authors should examine how this variable is distributed according to the calculation scenarios analyzed.
· The authors say that the P=5% event «Upon encountering a design flood that occurs once in twenty years.” This statement is incorrect, as the annual probability of the event will be 5%, and the likelihood of overcoming that event in the next 20 years is given as
P(X>Q)n=1-(1-1/T)n=1-(1-1/20)20=0.641
· The discussion is a section where the authors compare their results with other studies and where the conclusions are subsequently based. The section presented by the discussion authors should be rewritten entirely, comparing their results with other studies, and even part of the current text should be moved to the introduction.
· Authors should review the sub-indices and supra-indices of the variables.
Therefore, I believe the article can be accepted in its present form after major revision.
Author Response
Comments 1:The introduction is brief, and there are no references to similar studies. It should also be discussed whether other authors have studied criteria of affection depending on the values of height and speed and their product, and what regulations exist that oblige this type of study.
Response 1: Thank you for your valuable suggestions. In the process of revising the manuscript, we noticed that there are limited references to studies on flood impacts. In this regard, we have added the following: A study was conducted to simulate the failure process of the Tangjiashan weir using the DB-IWHR and HEC-RAS models, which provided an in-depth discussion of the techniques for calculating and predicting weir failure floods. The study analysed in detail the effects of key parameters such as water level elevation, reservoir capacity curve and breach flow on the breaching process, which are added to lines 74-78 of the manuscript. Meanwhile, in recognition of the importance of dam breaching research in the international arena, we have added the relevant content to lines 83-89 of the manuscript in order to enrich and complete our research discussion.
Comments 2:Authors should change the structure of the manuscript by introducing a "Materials and Methods" section describing the models used.
Response 2: Thank you for your valuable comments. Regarding your suggestion to introduce a description of the model used in the ‘Materials and Methods’ section, I understand that although I am using a mathematical model, which does not involve physical materials in the traditional sense, I fully agree with the importance of clearly describing the model construction and computational methods in the thesis. For this reason, I am creating a new section in the revised version of the manuscript, named Model and Methods, in which I will describe in detail the process of constructing the mathematical model, including the assumptions of the model, the derivation of the mathematical equations, the selection of the parameters, and the method of solving the model. See Section 2 for more details.
Comments 3:A flow chart describing how the authors have developed the methodology proposed by the manuscript is much needed.
Response 3: Thank you for your valuable comments and concern about the clarity of the article. I fully agree with you that a detailed flowchart will greatly help the reader to understand the steps and logic of our numerical simulation study of flood dam failure. I have drawn a flowchart which will clearly show the entire methodology of the study from model construction, parameter selection, and analysis of results, which can be seen in Figure 1 of the manuscript.
Comments 4:There are no references about DB-IWHR model
Response 4: Thank you for pointing out the missing references on the DB-IWHR model in the manuscript. I apologise for this, I have rechecked the relevant literature and indeed found that we have omitted key references when citing the DB-IWHR model, I have included these additional references in the revised manuscript [14], [15], and I believe that these modifications will enhance the academic rigour of the article and provide readers with more comprehensive information.
Comments 5:Line 89 2.2 Scrub model or 2.2 Scour Model?
Response 5: Thank you for your careful review. The problem you pointed out in section 2.2 （now section 2.1.2）does exist, and the correct terminology should be ‘scour model’ rather than ‘Scrub model’. We are aware of this error and will correct it immediately. We apologise for the error and thank you for your help in ensuring the accuracy and professionalism of our paper.
Comments 6:A figure showing each of the parameters used would be necessary to describe the dam break model.
Response 6: Thank you for your insightful comments on the need for visual representation of the parameters used in the dam failure model. Following your suggestion, I have added a detailed table to the manuscript listing each parameter, unit and reference value. The table provides a clear and concise overview of the parameters involved in the model, which I believe will deepen the reader's understanding of the structure and function of the model. I have included this table as Table 1 and it meets the criteria of clarity and completeness of the model description，This portion of the description is on lines 223-230 of the manuscript.
Comments 7:Line 94; what is zult?
Response 7: Thank you for your question. We note that the definition of Zult is indeed not elaborated in the manuscript, which is indeed an oversight on our part. We would like to add that Zult represents the asymptote of the curve, i.e., the limiting value of the erosion rate. Specifically, as the velocity v tends to infinity, the asymptote value of the curve, Zult, tends to 1/b. In the model setup, the constant k is set to 100, and the parameter 1/a represents the initial slope of the curve when the velocity v is zero. The construction of the model is based on an in-depth analysis of the erosion resistance of the soil material, whose ‘strength’ should not be regarded as infinite. Based on the model parameters, we determined a=1.1, b=0.0003, and shear stress τc=30 Pa. With these settings, the calculated value of Zult is 3.333 mm/s. We have added this section to lines 127-134 of the manuscript, and we sincerely apologise for the previous omission, and hope that this detailed explanation will help you to better understand our study.
Comments 8:The reviewer does not understand the expression "ulcer" to refer to the process of rupture. Is it possible that the authors mean breakage zones?
Response 8: Thank you for your review comments. I apologize for the confusion caused by the use of the term ‘ulcer.’ This was not the appropriate term to describe the process of a dam breach. What I intended to refer to is the point at which the dam structure fails and creates an opening, commonly known as the ‘breach.’ The correct term should indeed be ‘breach’ to accurately describe the process of the dams structural failure and the resulting opening. I will revise the text accordingly to use ‘breach’ instead of ‘ulcer’ to avoid any further misunderstanding.
Comments 9:A table with all analysed breakage data is necessary, including the addition of all calculated breakage hydrographs in Figure 3.
Response 9: Thank you for your valuable comments. In response to your comments, I have prepared and included in the manuscript a detailed table (Table 3) and figure (Fig. 4) that provide a more complete visualisation of the dam failure process. I believe that these additions will improve the clarity and completeness of the document, and I hope they meet your expectations.
Comments 10:Overtopping failure is predominant in dams, but the authors do not comment on possible tubification failure. This should be discussed even in the introduction, as well as if possible, a comparison of maximum flow rates of overtopping and piping failure and their difference in the propagation of the dambreak wave.
Response 10: Thank you for your in-depth comments and meticulous review of the content of the paper. I fully agree with you that tubification failure, in addition to Overtopping failure, is an equally important aspect that should not be ignored when exploring the mechanisms of dam damage. This type of failure usually occurs when the water level in a reservoir rises sharply, and water flows through defects or cracks in the dam structure, creating a high-velocity flow that in turn erodes the construction materials and ultimately leads to the collapse of the dam structure. We have added this section to line 89-98 of the Introduction section of the manuscript, and in this study our focus is primarily on the mechanism of dam failure in the case of diffuse roof failure, but we will ensure that the effects of tubular failure are also given due consideration and discussion.
Comments 11:The authors say (Line 189-190):
“From the many simulation data, it can be concluded that the higher the starting level of simulating flood, the shorter the duration of the dam failures, and the larger the maximum discharge flow.”
This sentence must be quantitatively justified by the results obtained.
Response 11: Thank you for your valuable comments.In the revised manuscript, I have supplemented the model data by detailing the dam failure flood process lines for 12 different locations and operating conditions. These data clearly demonstrate the correlation between the initial water level and the duration of dam failure as well as the maximum flow, thus supporting the conclusion that higher initial water levels lead to shorter dam failure durations and higher maximum flows. These results can be seen in Figure 4, and these added data and analyses will enhance the findings of the paper and provide the reader with a more solid evidence base to support them. We expect that the revised manuscript will meet your expectations.
Comments 12:What does "grid encrypted" mean? Adjusted?
Response 12: Thank you for your question. The term ‘mesh encryption’ mentioned in the article refers to the process of increasing the number of meshes by decreasing the size of the mesh within a given study area, thereby increasing the spatial resolution of the model. This process is often used in numerical simulations to capture and analyse changes in certain key regions or phenomena in a finer detail. In the manuscript, we achieve grid encryption by resizing a grid with an original side length of 300 metres into two different grid sizes, 240 metres and 360 metres. Specifically, resizing the grid to 240 m is an encryption of the original grid, while resizing the grid to 360 m is a relatively sparse grid setup. We used these two different scenarios to observe and analyse the effect of grid size on the flood simulation results. Through this adjustment, we are able to explore the effects of different grid resolutions on the accuracy and computational efficiency of flood simulations, thus providing a basis for choosing an appropriate grid size. We have added more detailed explanations in the corresponding parts of the text, in lines 389-399 of the manuscript, to help readers better understand the concept of grid encryption and its application in research.
Comments 13:In Figure 8, the legend values do not match Table 1.
Response 13: Thank you for pointing out the mismatch between the legend values in Figure 8 (now Figure 9) and Table 1(now Table 3) . Your observation is very accurate. Indeed, Figure 9 presents the Manning value (1/n), whereas Table 3 lists the roughness as n. In order to eliminate this discrepancy and to improve the readability and consistency of the paper, we have added a column to Table 3 that lists the corresponding Manning value (1/n). This will make it easier for the reader to understand and compare the data by directly finding the Manning value in Table 3 that corresponds to the legend of Figure 9.
Comments 14:The authors do not analyze propagation times. This variable is crucial for the management and planning of a potential emergency. The authors should examine how this variable is distributed according to the calculation scenarios analyzed.
Response 14: Thank you for your valuable comments. Indeed, flood propagation time is crucial in guiding the population for emergency evacuation and risk avoidance transfer. For this reason, we have added data on the time of arrival of flood flow at each critical point in Table 4 as an important basis for risk assessment and transfer decisions. The analyses show that the flood water arrives extremely fast, and under the same geographical location, the higher the flood frequency, the shorter its arrival time, and accordingly, the more serious the disaster impact caused. In addition, under the same flood frequency conditions, the higher the location of the dam failure, the shorter the arrival time of the flood peak, which in turn leads to more severe flood disasters. These findings provide an important reference for the dynamic characteristics of flood propagation and the development of effective emergency response strategies.These can be seen in line 371-376 of the manuscript.
Comments 15:The authors say that the P=5% event «Upon encountering a design flood that occurs once in twenty years.This statement is incorrect, as the annual probability of the event will be 5%, and the likelihood of overcoming that event in the next 20 years is given as
P(X>Q)n=1-(1-1/T)n=1-(1-1/20)20=0.641
Response 15: Thank you for your careful review and correction of the accuracy of the presentation. The term ‘P=5 per cent flood’ is intended to describe a particular concept of return period, which refers to the 5 per cent likelihood that a flood of a particular magnitude will occur in any individual year. In other words, if we look at a consecutive 100-year time period, there will be, on average, about five years in which a flood of this magnitude will be experienced. The so-called return period defines how many years, on average, a particular flood size will occur. For the ‘P=5 per cent flood’, this corresponds to a return period of about 20 years, which is derived from 1/0.05 = 20, so we can understand that a flood of this magnitude will occur about once every 20 years.
Comments 16:The discussion is a section where the authors compare their results with other studies and where the conclusions are subsequently based. The section presented by the discussion authors should be rewritten entirely, comparing their results with other studies, and even part of the current text should be moved to the introduction.
Response 16: Thank you for your insightful comments and suggestions on the discussion section of our manuscript, and in response to your feedback, I have rewritten the discussion section to address this issue. The revised discussion now includes a comparison of our findings with the existing literature, highlighting the complexity of the dam failure process and the factors that influence it in preparation for the subsequent analyses and discussions, which can be seen in lines 438-456 of the manuscript.
Comments 17:Authors should review the sub-indices and supra-indices of the variables.
Response 17: Thank you for your valuable comments. We will meticulously review each variable involved in the text and thoroughly proofread its sub-indices and supra-indices to ensure their accuracy and consistency. In the forthcoming revised manuscript, we will correct the identified problems accordingly.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsManuscript Number: Water-3215043
Title”
The coupled application of the DB-IWHR model and the MIKE 21 model for the assessment of dam failure risk”
The manuscript describes a dam-break case study utilizing the DB-IWHR and the MIKE 21 model.
The authors have improved the manuscript, and all questions have been appropriately answered.
The authors have aligned themselves with the requirements of the journal.
I am of the opinion that the article can be accepted
.
