Flood Inundation Assessment in the Low-Lying River Basin Considering Extreme Rainfall Impacts and Topographic Vulnerability
Round 1
Reviewer 1 Report
This manuscript has good potential for publishing in this journal. Before publishing some corrections are required:
Discussion part should be developed, please compare the result of this study by other researchers’ results.
Conclusions quality and quantity should be improved. Please add some conclusion and also add some recommendations.
Figure 8 needs more explanation.
Figure 4 should be discussed more.
Newly publications are required for literature reviews.
Figure 9 and 10 need more descriptions.
Put some numeric results in Abstract.
Reduce self-citations.
Author Response
Response to Reviewer 1 Comments
Reviewer 1: This manuscript has good potential for publishing in this journal. Before publishing some corrections are required.
Response:
We thank you too much for taking time to consider our work and your wonderful comments. Thank you for thinking that our manuscript has good potential for publishing in this journal. Your comments have played a vital role in improving the quality of this paper. I would like to express my heartleft thanks again to you. Herein, we would like to address your valuable feedback below.
Point 1: Discussion part should be developed, please compare the result of this study by other researchers’s results.
Response 1:
We thank the reviewer for this comment. In the revised manuscript, we have improved the discussion to be better. We have conducted to compare our results to other researchers’ results.
Modified part:
Discussion section: Page 19, L608-621 ~ Page 20, L622-L665.
Point 2: Conclusions quality and quantity should be improved. Please add some conclusion and also add some recommendations.
Response 2:
We appreciate the reviewer’s comment. According to the reviewer’s suggestion, we have rewritten the Conclusions to be better in the revised manuscript.
Modified part:
Conclusions section: Page 20, L666-L674 ~ Page 21, L675-L706
Point 3: Figure 8 needs more explanation.
Response 3:
We thank the reviewer for this comment. In the revised manuscript, we have added more explanations for Figure 8 for better clarity. In the revised manuscript, we removed Figure 6, therefore Figure 8 is changed to Figure 7.
Modified part: Page 15, L509-L516 ~ Page 16, L517-L530.
Point 4: Figure 4 should be discussed more.
Response 4:
We appreciate the reviewer’s suggestion. We have discussed more results of Figure 4 for better clarity in the revised manuscript.
Modified part: Page 12, L405-L424.
Point 5: Newly publications are required for literature reviews.
Response 5:
We thank the reviewer for the useful comment. In the revised manuscript, we have added more newly publications in the Introduction section to make the foundation for the arguments stronger.
Modified part: Introduction section: Page 1, L41-L45 , Page 2, L46-L58, Page 3, L102-L123.
Point 6: Figure 9 and 10 need more descriptions.
Response 6:
We thank the reviewer for this comment. In the revised manuscript, we have added more descriptions for Figure 9 and Figure 10 for better clarity. Because in the revised manuscript, we removed Figure 6; therefore, Figure 9 and Figure 10 is changed to Figure 8 and Figure 9, respectively.
Modified part:
- Page 16, L536-L549 ~ Page 17, L550-L551.
- Page 18, L563-L581.
Point 7: Put some numeric results in Abstract.
Response 7:
We appreciate the reviewer’s comment. According to the reviewer’s suggestion, we have put more numeric results in the Abstract in the revised manuscript.
Modified part: Abstract section: Page 1, L15-L28.
Point 8: Reduce self-citations.
Response 8:
We thank the reviewer for this suggestion. In the revised manuscript, we have reduced self-citations.
Author Response File: 
Author Response.docx
Reviewer 2 Report
A BRIEF SUMMARY
The paper titled “Flood Inundation Assessment in the Low-lying River Basin Considering Climate Change Impacts and Topographic Vulnerability” presents an interesting topic for readers of this Journal.
However, some open questions remain after reading the paper. Below is the list of some questions that need to be addressed.
- Probably a more accurate references research could help to add value for this topic. I suggest to add some more references especially in the "part 1 (introduction)" of the paper. I have indicated suggestions (published during 2020), but more can be added to make the foundation for the arguments stronger.
- Annis, A.; Nardi, F.; Petroselli, A.; Apollonio, C.; Arcangeletti, E.; Tauro, F.; Belli, C.; Bianconi, R.; Grimaldi, S. UAV-DEMs for Small-Scale Flood Hazard Mapping. Water 2020, 12, 1717. https://doi.org/10.3390/w12061717
- New approach for determining the quantiles of maximum annual flows in ungauged catchments using the EBA4SUB model. Młyński, D., Wałęga, A., Ozga-Zielinski, B., Ciupak, M., Petroselli, A. Journal of Hydrology, 2020, 589, 125198
- Continuous hydrologic modelling for design simulation in small and ungauged basins: A step forward and some tests for its practical use. Grimaldi, S., Nardi, F., Piscopia, R., Petroselli, A., Apollonio, C. Journal of Hydrology, 2020, 125664
- In your opinion, can you improve this study with a continuous hydrological modeling?
- I suggest to add more details on DEM data used for hydraulic modelling.
- In conclusion, the authors have to specify the novelty of the proposed approach and the future improvements. You have to replace conclusions; this paragraph now seems a supplementary abstract.
SPECIFIC COMMENTS:
Keywords. I suggest to add: “Hydrological modelling” and “Hydraulic modelling”
Author Response
Response to Reviewer 2 Comments
Reviewer 2:
This paper titled “Flood Inundation Assessment in the Low-lying River Basin Considering Climate Change Impacts and Topographic Vulnerability” presents an interesting topic for readers of this Journal.
However, some open questions remain after reading the paper. Below is the list of some questions that need to be addressed.
Response:
We thank you too much for taking time to consider our work and your wonderful comments. Thank you for thinking that our manuscript is an interesting topic for readers of this Journal. Your comments have played a vital role in improving the quality of this paper. I would like to express my heartleft thanks again to you. Herein, we would like to address your valuable feedback below.
Point 1: Probably a more accurate references research could help to add value for this topic. I suggest to add some more references especially in the “part 1 (introduction)” of the paper. I have indicated suggestions (published during 2020), but more can be added to make the foundation for the arguments stronger.
Annis, A.; Nardi, F.; Petroselli, A.; Apollonio, C.; Arcangeletti, E.; Tauro, F.; Belli, C.; Bianconi, R.; Grimaldi, S. UAV-DEMs for Small-Scale Flood Hazard Mapping. Water 2020, 12, 1717. https://doi.org/10.3390/w12061717
New approach for determining the quantiles of maximum annual flows in ungauged catchments using the EBA4SUB model. Młyński, D., Wałęga, A., Ozga-Zielinski, B., Ciupak, M., Petroselli, A. Journal of Hydrology, 2020, 589, 125198
Continuous hydrologic modelling for design simulation in small and ungauged basins: A step forward and some tests for its practical use. Grimaldi, S., Nardi, F., Piscopia, R., Petroselli, A., Apollonio, C. Journal of Hydrology, 2020, 125664
Response 1:
We thank the reviewer for this helpful comment. According to the reviewer’s suggestion. We have added some references in part 1 (Introduction) in the revised manuscript. We hope that it will make the foundation for the arguments stronger.
Modified part: Introduction section: Page 1, L41-L45, Page 2, L46-L58, Page 3, L102-L123.
Point 2: In your opinion, can you improve this study with a continuous hydrological modelling?
Response 2:
We appreciate the reviewer’s comment. In our future work, we will improve our results by assessing the change in flood inundation risk using the yearly rainfall data for the historical and future climate change scenarios extracted from rainfall dataset d4PDF. We believe that assessing the future flood inundation risk over a long time period that includes both wet and dry conditions would provide more reliable future projections in the target basin.
Point 3: I suggest to add more details on DEM data used for hydraulic modelling.
Response 3:
We thank the reviewer’s suggestion. In the revised manuscript, we have added more details on DEM data, which was used for hydraulic modelling.
Modified part: Page 9, L271-L287.
Point 4: In conlusion, the authors have to specify the novelty of the proposed approach and the future improvements. You have to replace conclusions; this paragraph now seems a supplementary abstract.
Response 4:
We thank the reviewer for this useful comment. We have rewritten the Conclusion in the revised manuscript to specify the novelty of the proposed approach and the future improvements.
Modified part: Conclusions section: Page 20, L666-L674 ~ Page 21, L675-L706
SPECIFIC COMMENTS:
Point 5:
Keywords. I suggest to add: “Hydrological modelling” and “Hydraulic modelling”
Response 5:
We thank the reviewer’s suggestion. According to the reviewer’s suggestion, we have added the keywords “Hydrological modelling” and “Hydraulic modelling” in the revised manuscript.
Author Response File: Author Response.docx
Reviewer 3 Report
Major remarks of the review may be summarized as follows:
1) A very similar research concerning the assessing climate change impacts on flood inundation (using the same method and for the same study area) has been presented by the Authors in the following paper:
Nguyen, T.T.; Nakatsugawa, M.; Yamada, T.J.; Hoshino, T. Assessing climate change impacts on extreme rainfall and severe flooding during the summer monsoon season in the Ishikari River basin, Japan. Hydrological Research Letters. 2020, 14, 155-161.
For this reason, the Authors should precisely specify new ideas which were added to their manuscript in comparison to the results presented in previous paper.
2) The Authors focused on estimating the impact of climate change on flood flows. As the Authors state, the extreme discharges in river and flood inundation mainly depend on growth in atmospheric precipitation related to the global increase in temperature. However, it should be noted that the Authors ignored the influence of such key factor as for example an urbanization which leads to increased sealing of the catchment area. The above-mentioned factor is not directly related to climate change, but also increases runoff from catchment and flood flows. Thus, this aspect requires a broader commentary in the manuscript. Moreover, it seems that the title of the manuscript, emphasizing the impact of climate change, does not correspond to the content of the manuscript. Therefore, I propose that the title should highlight only the effects of precipitation and topography, but not climate change.
3) The manuscript does not explain how the problem of infiltration was solved with the use of the Green-Ampt model when there is no continuous water supply on the ground surface. Such an assumption is required when using this model. Moreover, it was not specified for what type of soil and for which initial moisture conditions the simulations were conducted. It should be noted that if the average values of these parameters for the entire area were adopted, this is a significant simplification that requires a more in-depth comment in the manuscript.
4) The Authors seem not up-to-date with the literature on the flood inundation models. See for example only papers in Water MDPI:
Artichowicz W., Gąsiorowski D. (2019) Computationally efficient solution of a 2D diffusive wave equation used for flood inundation problems, Water, 11(10), 2195.
Ongdas, N., Akiyanova, F., Karakulov, Y., Muratbayeva, A. and Zinabdin,N. (2020) Application of HEC-RAS (2D) for Flood Hazard Maps Generation for Yesil (Ishim) River in Kazakhstan, Water, 12(10), 2672.
5) The analysis of rainfall data, which is crucial for the problem under consideration, is incomplete. For example, no data on changes in annual rainfall over the analyzed multi-year period were provided.
6) The Authors did not show how the 1D and 2D diffusive wave models were coupled.
Minor remarks
1) I propose to delete Eq. (3) and (4) that are common known. Instead, the 1D and 2D diffusive wave model should be better described. Give the equations, the coupling method, etc.
2) Lines 321-323. Similar content is repeated for the third time.
3) In Table 1 there is no value for the initial moisture content.
4) Figure 6 and the text on lines 366-370 do not add much, it can be removed.
5) Figures 8 and 11 are way too large.
Author Response
Response to Reviewer 3 Comments
Reviewer 3: Major remarks of the review may be summarized as follows:
Response :
We thank you too much for taking time to consider our work and your valuable comments. Your comments have played a vital role in improving the quality of this paper. I would like to express my heartleft thanks again to you. Herein, we would like to address your useful feedback below.
Point 1: A very similar research concerning the assessing climate change impacts on flood inundation (using the same method and for the same study area) has been presented by the Authors in the following paper:
Nguyen, T.T.; Nakatsugawa, M.; Yamada, T.J.; Hoshino, T. Assessing climate change impacts on extreme rainfall and severe flooding during the summer monsoon season in the Ishikari River basin, Japan. Hydrological Research Letters. 2020, 14, 155-161.
For this reason, the Authors should precisely specify new ideas which were added to their manuscript in comparison to the results presented in previous paper.
Response 1:
We thank the reviewer for the useful comment. According to the Reviewer’s suggestion, in the revised manuscript, we have added descriptions for the new ideas to clarify the difference between this study and our previous study.
Here, we want to show the difference between this study and our previous study:
In the previous study, we focused on assessing the climate change impacts on the Ishikari River basin on the following aspects:
- Assessing the change in extreme rainfall in the Ishikari River basin, as well as in seven Ishikari main sub-basins.
- Assessing the change in river discharge in the Ishikari River basin and in seven Ishikari main sub-basins.
- Evaluating the time difference between the time of peak discharge at the reference station in each sub-basins and the time of peak water level at the confluence point intersecting the main river.
In the previous study, we used the Integrated Flood Analysis System (IFAS) model coupled with the rainfall data of high resolution of 5 km extracted from d4PDF. However, the IFAS model uses the kinematic wave for river channel flow to evaluate the time difference; therefore, the time difference results might not accurately reflect the impact of the backwater phenomenon in vulnerable areas in the target basin.
From the previous results, we clearly indicated that the effect of climate change is significant in the sub-basins located in the southern part of the Ishikari River basin, especially the Chitose River basin, as it is located in a downstream lowland area of the Ishikari River basin. The Chitose River basin is considered to be the most flood-prone in the Ishikari River basin.
From the above reason, in this study, we focused on assessing the impacts of climate change on severe inundation risk in the Chitose River basin on some aspects:
- Assessing the change in future flood inundation risk comprehensively (including inundation area, inundation volume, peak inundation depth, inundation probability, inundation duration) considering the extreme rainfall impacts and the topographic vulnerability in the Chitose River basin, a downstream tributary of the Ishikari River using the RRI model.
- We want to improve the time difference prediction results in the Chitose River basin using the RRI model, which uses a 1D diffusive wave for the river channel and a 2D diffusive wave for the slope. We believe that the time difference might provide more reliable compared to the previous study results.
Modified part: Page 3, L124-L151.
Point 2: The Authors focused on estimating the impact of climate change on flood flows. As the Authors state, the extreme discharges in river and flood inundation mainly depend on growth in atmospheric precipitation related to the global increase in temperature. However, it should be noted that the Authors ignored the influence of such key factor as for example an urbanization which leads to increased sealing of the catchment area. The above-mentioned factor is not directly related to climate change, but also increases runoff from catchment and flood flows. Thus, this aspect requires a broader commentary in the manuscript. Moreover, it seems that the title of the manuscript, emphasizing the impact of climate change, does not correspond to the content of the manuscript. Therefore, I propose that the title should highlight only the effects of precipitation and topography, but not climate change.
Response 2:
We thank the reviewer for this comment. We agree with the reviewer’s comment. We understand that the land-use change and rapid development of the socio-economic would affect the uncertainty in the flood inundation prediction results. Therefore, the impacts of land-use changes and rapid development of socio-economic should be considered along the target basin. However, in this study, we focused on assessing the changes in natural flood inundation risk considering the extreme rainfall impacts and topographic vulnerability. We assumed that land-use activities are unchanged from the present to the future. The potential effect of land-use change, as well as the change by human effects, should be considered in the target basin in future work.
In the revised manuscript, we have added more comments for this aspect in the Introduction section, as well as we have written the future improvements in the Conclusions section.
In addition, according to the Reviewer’s suggestion, we have revised the title to be more appropriate with the content of this study. The revised title is:
“Flood Inundation Assessment in the Low-lying River Basin Considering Extreme Rainfall Impacts and Topographic Vulnerability”.
Modified part:
- Introduction section: Page 1, L41-L45 ~ Page 2, L46-L47.
- Conclusions section: Page 21, L692-L706.
Point 3: The manuscript does not explain how the problem of infiltration was solved with the use of the Green-Ampt model when there is no continuous water supply on the ground surface. Such an assumption is required when using this model. Moreover, it was not specified for what type of soil and for which initial moisture conditions the simulations were conducted. It should be noted that if the average values of these parameters for the entire area were adopted, this is a significant simplification that requires a more in-depth comment in the manuscript.
Response 3:
We thank the reviewer for this comment. In this study, we used the RRI model to evaluate the flood inundation risk in the Chitose River basin. The RRI model can take initial conditions for water depths on slope and river as well as the cumulative water depth in the Green-Ampt model. Hence, in this study, we have considered the initial condition for water depths on the slope, the river as well as the cumulative water depth in the Green-Ampt model. The simulations were conducted for an extra period of two weeks before the main period for model warmup and also for initial moisture condition in the target basin. In addition, the detail of the RRI model, as well as the infiltration loss is calculated with the Green-Ampt model was shown in the revised manuscript.
Modified part:
- Initial moisture conditions: Page 11, L385-L386.
- Details of the RRI model: Page 6, L186-L203; Page 7, L204-L232; Page 8, L233-L262.
Point 4: The Authors seem not up-to-date with the literature on the flood inundation models. See for example only papers in Water MDPI:
Artichowicz W., Gąsiorowski D. (2019) Computationally efficient solution of a 2D diffusive wave equation used for flood inundation problems, Water, 11(10), 2195.
Ongdas, N., Akiyanova, F., Karakulov, Y., Muratbayeva, A. and Zinabdin,N. (2020) Application of HEC-RAS (2D) for Flood Hazard Maps Generation for Yesil (Ishim) River in Kazakhstan, Water, 12(10), 2672.
Response 4:
We appreciate the reviewer’s suggestion. In the revised manuscript, we have updated the literature on the flood inundation models according to the reviewer’s suggestion.
Modified part: Page 3, L102-L123.
Point 5: The analysis of rainfall data, which is crucial for the problem under consideration, is incomplete. For example, no data on changes in annual rainfall over the analyzed multi-year period were provided.
Response 5:
We thank the reviewer for the helpful comment. In this study, we evaluated the change in flood inundation risk comprehensively in the Chitose River basin considering the short-term extreme rainfall impacts as well as the topographic vulnerability. In the previous study, we indicated the change in extreme rainfall between the analyzed rainfall events. The results indicated that the extreme rainfall is expected to increase significantly by 21.2 % in the entire Ishikari River basin, and 34.8% in the Chitose River basin. And from this study, we also indicated that the Chitose River basin should be paid attention to mitigate flood damage in the future because this river basin is located in a lowland area that is prone to flood damage.
Hence, in this study, we used the rainfall data results from the previous study to further understand the change in flood inundation in the Chitose River basin. We have added this information to the revised manuscript.
Modified part: Page 3, L124-L129.
Point 6: The Authors did not show how the 1D and 2D diffusive wave models were coupled.
Response 6:
We thank the reviewer for this comment. According to the reviewer’s suggestion, we have shown the detailed 1D and 2D diffusive wave models in the revised manuscript.
Modified part: Page 6, L186-L203; Page 7, L204-L232; Page 8, L233-L262.
Minor remarks
Point 7: I propose to delete Eq.(3) and (4) that are common known. Instead, the 1D and 2D diffusive wave model should be better described. Give the equations, the coupling method, etc.
Response 7:
We appreciate the reviewer’s suggestion. In the revised manuscript, we have removed the Equations (3) and (4) and added the equations of the detailed 1D and 2D diffusive wave models.
Modified part: Page 6, L186-L203; Page 7, L204-L232; Page 8, L233-L262.
Point 8: Line 321-323. Similar content is repeated for the third time.
Response 8:
We thank the reviewer for this comment. In the revised manuscript, we have removed these sentences to avoid repeating similar content many times.
Modified part: Page 12, L406.
Point 9: In Table 1 there is no value for the initial moisture content.
Response 9:
We thank the reviewer for this comment. In this study, we used the RRI model to evaluate the change in flood inundation risk in the Chitose River basin, a tributary of the Ishikari River basin. The RRI model can take initial conditions for water depths on slope and river as well as the cumulative water depth in the Green-Ampt model. The initial moisture content in the RRI model is not shown by the individual parameter. In this study, the simulations were conducted for an extra period of two weeks before the main period for model warmup and also for the initial moisture content.
We have added this information in the revised manuscript for better clarity.
Modified part: Page 11, L385-L386.
Point 10: Figure 6 and the text on lines 366-370 do not add much, it can be removed.
Response 10:
We appreciate the reviewer’s suggestion. According to the reviewer’s suggestion, we have removed Figure 6 and the text on lines 366-370 in the revised manuscript.
Modified part: Page 13, L452 ~ Page 14, L 453-L454.
Point 11: Figure 8 and 11 are way too large.
Response 11:
We thank the reviewer’s comment. In the revised manuscript, we have modified the size of Figures 8 and Figure 11 to be more appropriate. Because, in the revised manuscript, we removed Figure 6; therefore, Figure 8 and Figure 11 is changed to Figure 7 and Figure 10, respectively.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors improved manuscript accordingly, and this manuscript is acceptable.
Reviewer 2 Report
The document has been improved following referee's suggestions. In my opinion it is ready for publication.
Reviewer 3 Report
The manuscript has been accordingly corrected.
