Developing Flood Vulnerability Functions through Questionnaire Survey for Flood Risk Assessments in the Meghna Basin, Bangladesh

Round 1

Reviewer 1 Report

With this manuscript the Authors aimed at developing flood damage functions for estimating flood losses to rice crops and residential buildings in Bangladesh by taking advantage of information collected through field surveys and interviews with people experiencing flooding events in recent years.

The topic is very interesting and fits the scope of the Journal, however I think that the Authors should improve their manuscript before publication by considering the following points. In detail:

- I suggest to include a critical discussion of the new developed curves and a comparison (shape, considered variables, thresholds for damage occurrence, range of expected damage ratios, etc.) with other existing flood damage models for rice crops and buildings in Bangladesh and/or neighboring (similar) countries, in order to better highlight the novelty of your manuscript and the potential for the spatial transferability of the new developed functions (Scorzini et al. (2021, doi: 10.1016/j.ijdrr.2020.101999)). In doing this, the Authors should further improve their literature review, since there are also some other studies which provided modelling tools for estimating flood losses to rice as a function of flood depth and duration, as shown in Hussain (1995) “Decision support system for assessing rice yield losses from annual flooding in Bangladesh”, PhD Thesis, University of Hawaii. Other useful studies may be the following: Shrestha et al. (2021, doi: j.ejrh.2021.100872), Win et al. (2020, doi: 10.20965/jdr.2020.p0242; 2018, doi: j.ijdrr.2018.01.030).

- Moreover, as known from the literature, another important parameter for the vulnerability of rice crops is the growth stage of the plant (i.e. month of flood occurrence), which has been neglected here, because (I guess) of the typical seasonality of the floods in Bangladesh: this may be fine, but should be better underlined in the text of the manuscript.

- The Author could not perform a validation of the developed functions (due to the lack of sufficient specific empirical loss data for the investigated area): please better clarify this point by emphasizing the current limitation of the developed functions.

- While it is fine to rely on the information provided by the farmers for developing synthetic damage curves for rice (they are expert in this field), I am not sure the same can be said for what concerns the buildings. In using a “what-if” approach with a non-expert you may obtain a non-representative picture of the damage mechanisms. How did you handle the information they provided? Did you only rely on information about “experienced” losses? (i.e., is point (b) in Appendix A2 filled with actual damage information or with the damage they expect a certain water depth would produce to their houses?).

- The Authors considered the building value to provide a relative damage (0 to 100% damage): how was this building value estimated (i.e. data sources)? Is it a replacement or market value of the building? It seems you considered the first one, but it would be better to clearly state this. Moreover, in P17.L549-550, the Authors provided average values for construction costs of the buildings in the area: it would be useful to know also which is the average size of the buildings, in order to obtain a cost per square meter. Similarly, how did you estimate the value of the building content? Only by using information provided by interviewees? If yes, the previous comment also apply to this point.    

- It is true that flood damage to crops is usually expressed in terms of yield reduction, however a comprehensive modelling of this kind of losses would require a more complex analysis, involving also the assessment of the changes in production costs due to the flood, as shown for instance in Pivot et al. (2002, doi: 10.1016/S0022-1694(02)00136-1), Morris and Brewin (2014, doi: 10.1111/jfr3.12041) and in Molinari et al. (2020, doi: 10.5194/nhess-19-2565-2019). This point should be clarified in the manuscript.

Minor comments:

- Although the sense is always clear and English usage is almost correct, writing fluency could be improved.

- P3. L120: missing “there” between “rivers” and “are”.

- P3. L123: please specify that “Haors” are typical wetlands in Bangladesh, because not everyone may know it.

- P8. L324-333: please delete this part, given that it is a repetition of previously mentioned points.

- P11. L401-403: the Author mention that “One important finding revealed from the developed curves was that there will be no damage to Boro paddy when the water level remains up to an average of 25 cm depth (at which the tiller of rice evolves)”: actually, this is already well known (and obvious). Please consider to weaken the strength of that “one important finding”.

- I would consider plotting the functions for rice in relative terms (i.e. “yield loss” – 0 to 100%), as usually done in most of the literature (i.e. ratio of “actual”(reduced) yield due to inundation to maximum expected yield (without inundation)).

Author Response

Dear Reviewer,

Please find attached our detailed point-by-point responses to your comments on our manuscript entitled “Developing flood vulnerability functions through questionnaire survey for flood risk assessments in the Meghna basin, Bangladesh”. The manuscript’s ID is water-1514561. We thank you for your constructive comments which have contributed substantially to improving the manuscript. Accordingly, we have made significant efforts to revise the manuscript, with the details being explained in the attached file.

Thanking you again.

Sincerely,

Islam M. Khairul (corresponding author)

Author Response File: Author Response.docx

Reviewer 2 Report

The authors proposed synthetic flood damage functions for agriculture and rural households through a questionnaire survey conducted in the northeastern part of Bangladesh. This type of studies have an importance because it is the first study on flood damage estimation through damage functions in the study area. There are some comments listed below.

1) Only flood depth used as a variable to calculate damage. Is it possible to include other variables such as duration and flow velocity in the damage function.

2) It would be better if a flood hazard map can be supplied even if with very high resolutions. Flood vulnerability assessment may require flood hazard maps for an integrated evaluation.

3)  For the validation of regression equations the data can be divided into two parts as training and testing. Training data can be used for model setup and remaining data is employed to test the proposed model.

 

Author Response

Dear Reviewer,

Please find attached our detailed point-by-point responses to your comments on our manuscript entitled “Developing flood vulnerability functions through questionnaire survey for flood risk assessments in the Meghna basin, Bangladesh”. The manuscript’s ID is water-1514561. We thank you for your constructive comments which have contributed substantially to improving the manuscript. Accordingly, we have made significant efforts to revise the manuscript, with the details being explained in the attached file.

Thanking you again.

Sincerely,

Islam M. Khairul (corresponding author)

Author Response File: Author Response.docx

Reviewer 3 Report

A BRIEF SUMMARY

The paper titled “Developing flood vulnerability functions through questionnaire survey for flood risk assessments in the Meghna basin, Bangladesh”, presents a good topic for readers of this Journal. The topic represents a line of research as interesting as studied. However, the manuscript need to be improved.

Some question remain after reading the paper. Below is the list of questions that need to be addressed.

 

• I believe it would be appropriate to specify the novelties of this manuscript with respect to your previous studies. These novelties must also be reported in the conclusions.

 

• You have to add more details on “marginal flooding areas”, in order to better clarify your analysis. I suggest to increase references list with following suggestions (on similar topic):

https://doi.org/10.3390/geosciences8040112

https://doi.org/10.1007/s11269-020-02567-8

https://doi.org/10.1038/s41597-021-01048-w

Author Response

Dear Reviewer,

Please find attached our detailed point-by-point responses to your comments on our manuscript entitled “Developing flood vulnerability functions through questionnaire survey for flood risk assessments in the Meghna basin, Bangladesh”. The manuscript’s ID is water-1514561. We thank you for your constructive comments which have contributed substantially to improving the manuscript. Accordingly, we have made significant efforts to revise the manuscript, with the details being explained in the attached file.

Thanking you again.

Sincerely,

Islam M. Khairul (corresponding author)

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The Authors have properly addressed my main concerns on their study, by including also a section related to the validation of the developed functions. Therefore, the manuscript can be now considered suitable for publication in its current form.

Reviewer 2 Report

The authors have implemented my recommendations in the new version. Now, it seems to be acceptable. 

Reviewer 3 Report

The paper has been improved. In my opinion it is ready for pubblication. Congratulations.