Regional Flood Frequency Analysis of the Sava River in South-Eastern Europe

Round 1

Reviewer 1 Report

This is an interesting and well structured paper, but this reviewer has found some questions that the authors need to solve or make clearer.

This is an interesting and well structured paper, but this reviewer has found some questions that the authors need to solve or make clearer.

Firstly, but not the more important, in line 33, it is told about the extreme flood events since the 1990s. Reader can deduce this period was specially intense in these events. But, the main floods in Serbia (line 94) are more frequent before 1990s, six from eight cases. It would be interesting to give a more extent view of the floods, and more when the data series analysed in paper are from 1961 to 2020. Some references are fine to help in this question:

https://www.researchgate.net/profile/Gerardo-Benito/publication/283600391_Historical_Floods_in_Europe_in_the_Past_Millennium/links/56b336ff08ae56d7b06e35d5/Historical-Floods-in-Europe-in-the-Past-Millennium.pdf

https://www.taylorfrancis.com/books/edit/10.1201/b12348/changes-flood-risk-europe-zbigniew-kundzewicz

Secondly, we have the causes of flood. The authors don't follow a straight line of thinking about thid item. In the introduction, it is expected an increase due to climatic change, but due to population and economic growth (line 36). In line 81, it showed only the meteorological causes of the floods. Nothing about more population or its location in areas with flood risk.  The authors don't mention the demographic characteristics of the research area. But, in the conclusions, we can read about the importance of human factors, such as the degree of human interventions (line 527) or that this study can help in decision for urbanization, regulations and management. If the study is a good tool for these questions, it would be interesting how the human actions influence water discharge and the effects of floods.

The next point is about the main question in the paper. It seems evident the great contribution is the method, but it is very interesting the result section. Once included, the authors should get more out of it. There is no time series graph, from both individual stations or an average data, to test the evolution of floods. These graphs could make clear if the floods have increase from 1990, or not. It is included a table (No. 3) with slope estimates. In the text we can read about the causes of decreasing river discharges, but these negatives trends are only two of six stations. Three questions:

why are not presented the causes of positive trends? Is this not a different result from the previous researches (line 390)? With these such diverse trends, is the investigated area actually homogeneous, like it is concluded (line 514)?

The figure 2 is not included in the text. Or it is not included in the pdf version from the journal.

I think these items are going to make better the paper.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The paper looks interesting, especially, during the time of unprecedented climate change and impacts in Eastern Europe. Few comments are here for the authors to improve the readability and soundness of the papers as such:

1. In the introduction, floods are considered an important natural disaster around the world. Few information related to damage done, and few estimated costs (i.e., life, well-being, insurance, etc.) would be interesting for international scholars to know about the importance of this paper.

2. Interestingly, Bangladesh is one of the very few countries regularly experiencing floods and there are several studies recently conducted. In the introduction, I have seen few old studies and claimed as high resolution data source. I disagree with this definition of high resolution dataset in and around 2005. A recent study may help the author to see the progress of higher spatial and temporal resolution to model the flood havoc - https://link.springer.com/article/10.1007/s41748-022-00295-0 

3. The regional frequency distribution is critical and this is one of the important outcomes of this research. Please provide few more references to demonstrate that you have considered the latest methods and models of RFFA in North American and Australian context!

 

4. In the method, the trend estimation looks nice. However, I have not seen any validation measures adopted in this method section. Satellite data/ Geospatial information might be an option to employ the validation. Or else, the authors may split the data into 85% and 15% to use the later for validation. Otherwise, the model looks a little questionable for the international readers.

5. results look interesting. However, few discussion should be explained in one or two more sentences in several places. For example, Homegeneity assessment is done with the REFA system. However, does this look a little different in other part of the EU/World? Why this information is so critical for the decision makers? Need to explain so that the readers can carry out a message from your key findings.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

Thanks for the interesting manuscript. My main recommendations for improving it are as follows:

1. It is necessary to present the novelty of your research more clearly. What are the advantages of the proposed approach compared to other approaches? Is this the first application of this approach for the region studied?

2. It would be informative and illustrative if you presented long-term series of changes in the maximum daily water discharge in the Sava River basin at all six gauging stations for the entire observation period. It is desirable to do this on one chart. It is also desirable to highlight the trends in this discharge.

3. I strongly recommend that you provide information about the main limitations and uncertainties of your study (perhaps as a separate subsection of the manuscript). You need to be more critical of your own results.

4. I do not agree that you classify the Sava River basin as part of South-Eastern Europe. Europe stretches from the Atlantic to the Urals and the Black Sea and Caspian Sea. What you have highlighted on your map in Figure 1 is only a part of Europe, and a politically biased one at that. Thus, South-Eastern Europe is the south of Ukraine, the Lower Volga region, part of the Caspian Lowland. The Sava River basin is located rather in Southern Europe. Therefore, I strongly recommend writing "Balkan Peninsula" in the text and title of the manuscript instead of "South-Eastern Europe". This is geographically correct. Please see, for example: https://www.britannica.com/search?query=Europe

6. I did not find Figure 2 in the manuscript. Apparently, it accidentally disappeared. Please, put the manuscript in order for the next round of peer review.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Thanks for the revision.