Development of Flood Risk and Hazard Maps for the Lower Course of the Siret River, Romania

Round 1

Reviewer 1 Report

Personally, I would prefer more discussion devoted to the differences between 1D and 2D models as well to the impact of the Danube River.

Figures numbering needs correction

Small inaccuracy I realized for lines 155 or 261.

Paper is logically correct, each step is discussed and justified. Same is valid for results presentation.

Average ratings are applied due to the fact, that more applications for flood risk and for hazard maps creation with the help of HEC-RAS 1 D software were presented already.

Author Response

Thank you for the time put into revising our manuscript. We appreciate the careful review and constructive suggestions, which helped to improve our manuscript. The revision has been developed in consultation with all coauthors, and each author has approved the final form of this revision.

A detailed item-by-item/ block response (in italics, including how and where the text was modified in the manuscript) to suggestions are attached. We hope that our answers are satisfactory and in line with your comments.

Author Response File: Author Response.docx

Reviewer 2 Report

General Comments

Generally, the development of flood risk and hazard maps consist of a quite common process with low scientific content. The manuscript may refer to a complex process of summarizing different techniques, such as hydrological and hydraulic modeling, however this is a methodology followed in many previous scientific manuscripts. To my opinion the use of numerical models to produce hazard maps etc. contains insignificant novelty. 

In addition, I think that the use of 1D hydraulic model is not sufficient, since there is also the selection of using HEC-RAS 5.0, which is a 2D option, which contains definitely more sufficient spatial information. The authors do not define what is the specific version of the HEC-RAS model used in this scientific work, they are referring only to the 1D model use. I am wondering why the authors did not use the 2D modeling capabilities option included in HEC-RAS 5.0 along with the RAS Mapper option. 

Finally, the text should be extensive reviewed and edited regarding the English language from an expert. There are too many points within the text with grammar mistakes. I recommend to review very carefully the document.

Introduction 

The Introduction section needs to be seriously enriched. The review under the methods used is very poor. 

There is a case study description within the Introduction section which should be removed to the Study area and data section below. May be an extended comparison between the 1D-2D models should be included and an extended review on methods and previous publications used for the development of flood risk and hazard maps in several areas worldwide. The difference of the approach used within this manuscript should be extensively analyzed within the Introduction section. What is the innovation of this manuscript compared to other scientific research and what is the asset of the methodology used here?

Study area and data

What is the process of developing the DEM file from Light Detection Ranging (LIDAR) data? Is this process inccluded within the innovation of this manuscript or the DEM was already completed by other scientists and it has been only used as a DEM file in this work? 

Results and discussion - Conclusions

Among the 88 digitized cross-sections there was not any calculated cross-section within the field? There was not any validation process of these digitized cross-sections with respective measured data? I would like to see the results of some validation process. 

So in the section of results I can see that the analysis is also extended to the floodplains. In this case I will not agree once again with the use of 1D model. I think that this analysis is insufficient, especially in cases that the flood extent needs to be defined herein and accordingly the flood risk. I highly recommend to use the combined 1D/2D HEC-RAS (HEC-RAS 5.0) for such an analysis.  

Figure 5 should be better presented. Each figure should be seperately placed within the text in order to be better understood.

I am still wondering what the results and conclusions of this study would be if the 2D model option was used. May be the comparison of the results among the use of these two options (1D and combined 1D/2D models) could form a more innovative scientific article.

Author Response

Thank you for the time put into revising our manuscript. We appreciate the careful review and constructive suggestions, which helped to improve our manuscript. The revision has been developed in consultation with all coauthors, and each author has approved the final form of this revision.

A detailed item-by-item/ block response (in italics, including how and where the text was modified in the manuscript) to suggestions are attached. We hope that our answers are satisfactory and in line with your comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Thank you very much for taking into consideration all the previous comments. 

At first, I would like to make a comment regarding a mistake of mine in the previous review. The comment was for Figure 15 within the section of Results and Discussion (I had divided the comments according to the sections of the manuscript). However I have written by mistake Figure 5 and the authors improved that Figure. I have to admit that even by mistake, it is better the new version of Figure 5, and I suggest to improve also Figure 15 within the Results and Discussion section. Each figure should be seperately placed within the text in order to be better understood.

Furthermore, I believe that there are too many recent references with combined use of 1D/2D model which should be also noted and compared with the specific work. It would be constructive a further comparison and analysis. I suggest some manuscripts but there are much more in the bibliography.

Patel et al., 2017. Assessment of flood inundation mapping of Surat city by coupled 1D/2D hydrodynamic modeling: a case application of the new HEC-RAS 5. Nat Hazards 89, 93–130 (2017). https://doi.org/10.1007/s11069-017-2956-6

Vozinaki et al., 2017. Comparing 1D and combined 1D/2D hydraulic simulations using high-resolution topographic data: a case study of the Koiliaris basin, Greece, Hydrological Sciences Journal, 62:4, 642-656, DOI: 10.1080/02626667.2016.1255746

Jaiswal et al., 2020. Use of satellite imagery as river geometry in hybrid approach hydrodynamic modelling: A case study of 1-D and 2-D modelling for flood forecasting in Gandak River in Bihar, Roorkee Water Conclave

In addition, I suggest that the authors should include in the manuscript some information from their justification to the comment of using 1D model instead of combined 1D/2D. It would be useful to clarify the reader why this kind of modeling was used, the pros and cons of 1D modeling and any future plans or suggestion which could definitely improve the applied methodology. 

More specifically, it should be noted/pointed out within the text that this methodology is proposed for applications/2D simulations where there is luck of significant input data. It is also useful to know (when reading this manuscript) that the "main purpose of the manuscript is to present a low-cost method by which risk and hazard maps can be generated in previously unassessed areas". The novelty of the paper should be also noted herein once again, that is "the novelty is based on the concept which shows how to use multiple combined techniques and methods, to assess a flood extent and subsequently use this information for further purposes (i.e. flood defense strategies, flood management strategies, investment promotion activities, infrastructure damages etc.)". It should be also noted as future plan or suggestion for a better simulation methodology the use of coupled 1D-2D simulation models and justify it as "It is known that 2D simulations require much more complex input data and collaboration agrrements are needed to establish and build modern research vessel on environmental issues. Bathymetric equipment, topography and top software programs are necessary in such cases to enable the new research performance. In such case the comparison of modeling results could also take place among 1D models and 2D or coupled 1D/2D. 

Finally, I would like to point out that the manuscript should be extensive reviewed and edited regarding the English language from an expert. It is a comment also made in the previous version of my review and I did not see too much effort made within the manuscript. Please revise very carefully the manuscript regarding the English language. There are too many points within the text with grammar and syntax mistakes.

Author Response

Dear Reviewer,

Please see the attachment

We hope that our answers are satisfactory and in line with your comments.

Kindly regards, Arseni Maxim

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Thank you very much for taking into consideration all the previous comments. The manuscript has been improved.

I would suggest a final careful check and review regarding the English language from an expert.

I am noting some of the improvements that could take place within the text:

Line 12: There is an omitted “r” (River Siret)

Line 25: There is a space left after the word “maps”

Line 36: It is Flood Directive 2007/60/EC not Floods

Lines 53-54: Make it one paragraph

Line 55: efficient but gives… (the word “which” is not necessary)

Lines 54-63: Improve the English language of this paragraph

Line 67: May be better “…  is based on the requirement of high-accuracy input data…”

Line 77: A [A1] is left within the text, please correct it

Line 83: from economic, cultural and social points of view

Line 85: gives free access to use the HEC-RAS software, which is…

Lines 93, 95: 1D numerical model

Line 95: observed durations

Line 100: shows that HEC-RAS is …

Line 105: 1D HEC-RAS hydraulic modeling

Line 119: where no such measurements have taken place before

Line 120: to the input various water profiles

Lines 125-126: suffers severe flood events with environmental, economic and social impacts

Line 127: the area and the influence of the downstream confluence of River Siret with Danube River

Line 128: of Danube

Line 129: which causes most of the flooding in the area

Lines 140, 145: m3/s correct it may be using math equations

Line 260: …in order to describe the geometry of the main river channel…

Line 265: The calibration of the channel flow was obtained…

Line 373: it is observed (it may be better this phrase)

I would also like to note that it is better to write the word “figures” with capital F within the text.

Author Response

Dear Reviewer,

All the suggestion was taken into account. Please see the attachment.

Kind regard, 

Arseni Maxim

Author Response File: Author Response.docx