Trend Analysis of Selected Hydroclimatic Variables for the Hornad Catchment (Slovakia)

Round 1

Reviewer 1 Report (New Reviewer)

The work concerns the analysis of trends in mean annual precipitation, air temperatures and flows in the Hornad river basin in Slovakia. They were based on long, 50-year observation sequences.
It is a valuable study, very well developed both in terms of content, statistics and cartography. In addition to the cognitive aspects, it can also have practical significance and be used in various expert opinions and environmental assessments.

Minor comments and suggestions: 

1. I propose to enrich the analysis of the text in subsections 3.1.1, 3.1.2 and 3.1.3 by giving appropriate and specific values in brackets, eg. the lowest, average or maximum. This would make it easier for the reader to analyze the text and understand it.
2. On the graphs under Fig. 3, I propose to specify the significance level (p) and the number of pairs taken for analysis (N).
3. Unify the nomenclature of hydrological stations. Geographical names and sometimes symbols are used alternately in the work.

Author Response

Review 1

The work concerns the analysis of trends in mean annual precipitation, air temperatures and flows in the Hornad river basin in Slovakia. They were based on long, 50-year observation sequences.
It is a valuable study, very well developed both in terms of content, statistics and cartography. In addition to the cognitive aspects, it can also have practical significance and be used in various expert opinions and environmental assessments.

Thank you for your valuable comments. We have made changes to the article as suggested by the reviewer.

Minor comments and suggestions: 

1. I propose to enrich the analysis of the text in subsections 3.1.1, 3.1.2 and 3.1.3 by giving appropriate and specific values in brackets, eg. the lowest, average or maximum. This would make it easier for the reader to analyze the text and understand it.

-We added values in sections 3.1. 3.1.2 and 3.1.3

2. On the graphs under Fig. 3, I propose to specify the significance level (p) and the number of pairs taken for analysis (N).

- We have removed these graphs from the text of the manuscript. We did not specify the significance level p, because we did not analyze the coefficient r² in the article

3. Unify the nomenclature of hydrological stations. Geographical names and sometimes symbols are used alternately in the work.

-We unified the names on the maps and in the text of the article

 

Author Response File: Author Response.docx

Reviewer 2 Report (New Reviewer)

This article deals with the trend analysis of selected hydroclimatic variables in Slovakia’s catchment. It is interesting and provides useful results for the examined catchment’s hydrology. Although, some improvements are necessary so as to be accepted for publication. The main issues that need to be addressed are given herein.

In the abstract, it is necessary to add some numerical results and not just describe the findings.  

The introduction is too short that can not meet the demands of a scientific article. It is more like an introduction for a poster presentation. This part needs significant improvements and citations of more scientific articles.

-          Start conservation about climate change and variability in general and particular in Europe. State the outputs of the latest IPCC report about future climate projection.

-          Highlight the importance of hydrometeorological variables for environmental monitoring. Also give examples (https://www.cjees.ro/viewTopic.php?topicId=652, https://doi.org/10.5194/piahs-369-75-2015 )  

-          The significance of the examined theme is also confirmed by similar analysis in mountainous ecosystems (https://doi.org/10.3390/cli6030075)

-          Mentioned possible use of the results for policymaking or elsewhere.

Which was the research gap? Also, clearly state the novel points compared with similar published research. Which is your added value.

Figure 1. Change the band 1 word in the legend with elevation (m a.s.l)

The Mann-Kendal test can also detect the timing of the occurrence of an absurd change as described in the literature.

Give the advantages of Sen’s slope method compared to the least square method.

Better mean average air temperature (2m) instead of average temperature.

There is no legend for the figure in line 160. Also, the same graph would be useful for the precipitation analysis.

 

 

Author Response

Review 2

Thank you for your valuable comments. We have corrected the article as suggested by the reviewer.

 

Comments and Suggestions for Authors

This article deals with the trend analysis of selected hydroclimatic variables in Slovakia’s catchment. It is interesting and provides useful results for the examined catchment’s hydrology. Although, some improvements are necessary so as to be accepted for publication. The main issues that need to be addressed are given herein.

In the abstract, it is necessary to add some numerical results and not just describe the findings. 

-We have corrected the abstract.

The introduction is too short that can not meet the demands of a scientific article. It is more like an introduction for a poster presentation. This part needs significant improvements and citations of more scientific articles.

- We have corrected the introduction. We added more references.

-  Start conservation about climate change and variability in general and particular in Europe. State the outputs of the latest IPCC report about future climate projection.

- We added a new IPCC report

- Highlight the importance of hydrometeorological variables for environmental monitoring. Also give examples (https://www.cjees.ro/viewTopic.php?topicId=652, https://doi.org/10.5194/piahs-369-75-2015 )

- We added

- The significance of the examined theme is also confirmed by similar analysis in mountainous ecosystems (https://doi.org/10.3390/cli6030075)

- We added

- Mentioned possible use of the results for policymaking or elsewhere.

- In order to indicate long-term directions for policymaking, in particular for mountain catchments of temperate latitudes, monitoring of hydroclimatic variables should be continued and the analyzes of the second decade of the 20th century should be supplemented. However, we would like to thank the reviewer for drawing attention to the need to specify (e.g. in our other articles) issues related to policymaking.

Which was the research gap? Also, clearly state the novel points compared with similar published research. Which is your added value.

-We added

Figure 1. Change the band 1 word in the legend with elevation (m a.s.l.)

-We corrected

The Mann-Kendal test can also detect the timing of the occurrence of an absurd change as described in the literature.

-Thank you very much for this indication. Describing an timing of the occurrence of a change would be an excellent start point for future analysis and articles (for this research area).

Give the advantages of Sen’s slope method compared to the least square method.

-We added to the text: ‘Theil-Sen estimator makes no assumption about the distribution of the data and may be more robust against outliers in the comparison to Ordinary Least Squares (OLS) (Bulut and Cormier, 2018).’

Better mean average air temperature (2m) instead of average temperature.

-In the article we explain how the average values were calculated, so we believe that average is the right word.

There is no legend for the figure in line 160. Also, the same graph would be useful for the precipitation analysis.

-We removed this figures. All annual sums of precipitation, air temperature and flows are presented in the supplement.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report (New Reviewer)

The authors adressed all the reviewer comments

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

 

General Comments:

 

This study is relatively straightforward examining annual and monthly trends in temperature, rainfall, and runoff in Slovakia, in particular the Hornad River catchment for a 50-year period from 1960 - 2010. The authors show the 50-year trend and whether or not these were statistically significant. Then the authors examine the period by dividing in it two looking at the trends in the earlier period versus the later period. They use ANOVA and Sen slop analysis to examine the trends. The methods were used correctly, and the conclusions supported by the methods used. The references are appropriate. The grammar is strong. This paper should be published since their analysis is unique as far as this reviewer is aware. However, the presentation needs to be improved. Some Figures are hard to read. Some suggestions are given below.

 

Major Comments:

11.       The authors use 50 years worth of data as provided by the Slovak government. If the latest 10 years were available that would be good. I understand the rationale for dividing the period in half because of the Sen Slope technique. However, the authors should consider interannual and interdecadal trends. It may be that this could be a separate topic or the subject of a future paper which can be expressed in a few sentences the discussion section. For example, epochs in the North Atlantic Oscillation jet stream would definitely influence these variables. The NAO modes are recognized as positive (1972 – 1995, and 2011-2018) and negative (1951 – 1972, 1996 – 2010). These epochs are somewhat visible especially in the temperature and runoff data.

Some references:

Wang, Y.-H.; Magnusdottir, G.; Stern, H.; Tian, X.; Yu, Y. Decadal variability of the NAO: Introducing an augmented NAO index. Geophys. Res. Lett. 2012, 39, L21702.

Woollings, T.; Franzke, C.; Hodson, D.L.R.; Dong, B.; Barnes, E.A.; Raible, C.C.; Pinto, J.G. Contrasting interannual and multidecadal NAO variability. Clim. Dyn. 2015, 45, 539.

 

22.       Section 3.3 – Seasonal variations is an appropriate title, however, the caption of Fig. 8a should be   “Monthly trends in the precipitation during the years…..  “     Because each month was shown and trends are used not a measure of variability.

Also would it be possible to combine Figs 8a and b   through Figs. 10a and b   by using two different negative trend colors and two positive trend colors for each sub-period?    These figures are very big.   Also In Fig 9 the red and blue colors are difficult to see.

 

Minor Comments:

11.       There are a lot of figures in the paper. Perhaps the authors should consider making Figs. 3, 5, and 7 smaller by using one station that represents all 4.

22.       Figure 2, 4, 6 – please make the legends larger – these are difficult to read.

33.       Tables 5 - 7 – could this be made an appendix?

Author Response

Response for the reviewer 1

We appreciate the reviewer’s comments. The comments have been went through carefully, and revisions have been made accordingly. Following are the feedbacks for the reviewer’s comments.

This study is relatively straightforward examining annual and monthly trends in temperature, rainfall, and runoff in Slovakia, in particular the Hornad River catchment for a 50-year period from 1960 - 2010. The authors show the 50-year trend and whether or not these were statistically significant. Then the authors examine the period by dividing in it two looking at the trends in the earlier period versus the later period. They use ANOVA and Sen slop analysis to examine the trends. The methods were used correctly, and the conclusions supported by the methods used. The references are appropriate. The grammar is strong. This paper should be published since their analysis is unique as far as this reviewer is aware. However, the presentation needs to be improved. Some Figures are hard to read. Some suggestions are given below.

Major Comments:

11. The authors use 50 years worth of data as provided by the Slovak government. If the latest 10 years were available that would be good. I understand the rationale for dividing the period in half because of the Sen Slope technique. However, the authors should consider interannual and interdecadal trends. It may be that this could be a separate topic or the subject of a future paper which can be expressed in a few sentences the discussion section. For example, epochs in the North Atlantic Oscillation jet stream would definitely influence these variables. The NAO modes are recognized as positive (1972 – 1995, and 2011-2018) and negative (1951 – 1972, 1996 – 2010). These epochs are somewhat visible especially in the temperature and runoff data.

- We agree with the reviewer that it is possible to follow interannual and interdecadal trends. Such research material may be the subject of a future article.

 

Some references:

Wang, Y.-H.; Magnusdottir, G.; Stern, H.; Tian, X.; Yu, Y. Decadal variability of the NAO: Introducing an augmented NAO index. Geophys. Res. Lett. 2012, 39, L21702.

Woollings, T.; Franzke, C.; Hodson, D.L.R.; Dong, B.; Barnes, E.A.; Raible, C.C.; Pinto, J.G. Contrasting interannual and multidecadal NAO variability. Clim. Dyn. 2015, 45, 539.

- We did not study the impact of NAO on the variability of precipitation, air temperature and flow. We added the following in the discussion:

'Many researchers believe that the amount of precipitation and air temperature depend on the circulation in the North Atlantic region, which affects the whole of Europe (Wang et al., 2012; Woollings et al., 2015; Espinoza and Portela, 2022). The impact of NAO in the winter season is particularly visible. Research by Labudová et al., 2014 showed that the impact of the North Atlantic Oscillation on the sum of winter precipitation in Slovakia is zonal. The correlations between NAO and precipitations in eastern Slovakia are low, which may probably result from the occurrence of a natural orographic barrier such as the Carpathians'.

22. Section 3.3 – Seasonal variations is an appropriate title, however, the caption of Fig. 8a should be “Monthly trends in the precipitation during the years…..  “     Because each month was shown and trends are used not a measure of variability.

Also would it be possible to combine Figs 8a and b   through Figs. 10a and b   by using two different negative trend colors and two positive trend colors for each sub-period?    These figures are very big.   Also In Fig 9 the red and blue colors are difficult to see.

 - We agree with the reviewer, we changed the captions under the figures

Minor Comments:

11. There are a lot of figures in the paper. Perhaps the authors should consider making Figs. 3, 5, and 7 smaller by using one station that represents all 4.

- We resized the figures to contain less space

22. Figure 2, 4, 6 – please make the legends larger – these are difficult to read.

- We changed the size of the figures

33. Tables 5 - 7 – could this be made an appendix?

- We did not provide the tables in the form of an attachment, because they are very important in our study

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript investigates the long-term (1961–2010) trend in precipitation, air temperature, and streamflow over the Hornad River catchment in Slovakia. There are substantial drawbacks in this manuscript that make it inappropriate for publication in scholarly journals.

Main drawbacks:

- Lack of novelty: The manuscript is only a case study that implemented merely classical trend analyzing methods (Mann-Kendall trend test and Sen slop).

- Findings are not new. Calculations were limited to the year 2010.

- Introduction section is not to the point. In this section, the authors highlighted the impact of climate change on catchment hydrology; however, the study never consider climate change's impact on the study area. As the manuscript focuses on statistical trends in hydrological variables, the authors are suggested to review similar studies to figure out the most recent methods for analyzing trends.  

- Redundancy in citations, mostly irrelevant to the main topic. For example, only in the first paragraph of the manuscript, which can be entirely removed, the authors cited 22 papers awkwardly. 

- Some sentences are not useful. (e.g., line 41: The second group of studies focuses on detecting 41 changes in long time series using various research methods)

- Interactions between the variables (precipitation, temperature, and streamflow) were not discussed.

 

 

Author Response

Response for the Reviewer 2

We appreciate the reviewer’s comments. The comments have been went through carefully, and revisions have been made accordingly. Following are the feedbacks for the reviewer’s comments.

The manuscript investigates the long-term (1961–2010) trend in precipitation, air temperature, and streamflow over the Hornad River catchment in Slovakia. There are substantial drawbacks in this manuscript that make it inappropriate for publication in scholarly journals.

Main drawbacks:

- Lack of novelty: The manuscript is only a case study that implemented merely classical trend analyzing methods (Mann-Kendall trend test and Sen slop).

- In the study, we used a proven research methodology. The research area is located in a temperate transitional climate. The use of traditional trends made it possible to compare trends within different catchments. However, in line with the reviewer's remark (regarding the lack of novelty), in order to enrich the research procedure related to the study of trends, we supplemented the analysis with the multidimensional scaling method (MDS). The research procedure now consists of classic and exploratory methods. The use of multidimensional scaling proposed by us is a new approach for the area we are researching.

- Findings are not new. Calculations were limited to the year 2010.

- The presented studies cover the period for which hydrological data were available.

- Introduction section is not to the point. In this section, the authors highlighted the impact of climate change on catchment hydrology; however, the study never consider climate change's impact on the study area. As the manuscript focuses on statistical trends in hydrological variables, the authors are suggested to review similar studies to figure out the most recent methods for analyzing trends.  

- We have made a change in this part of the introduction

- Redundancy in citations, mostly irrelevant to the main topic. For example, only in the first paragraph of the manuscript, which can be entirely removed, the authors cited 22 papers awkwardly. 

- We have deleted the first paragraph

- Some sentences are not useful. (e.g., line 41: The second group of studies focuses on detecting 41 changes in long time series using various research methods)

- We have removed this sentence

- Interactions between the variables (precipitation, temperature, and streamflow) were not discussed.

- In the study, we added the multidimensional scaling method, which allows discussing the relationship between the trends of the analyzed hydroclimatic variables.

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

General Comments:

       The authors made some progress on some suggestions. These were meant to help make the paper more compact and maybe pack a stronger impact. Sometimes good science will not be effective because of presentation. Nonetheless, many of my suggestions were just suggestions and were not required by the authors. The science is still strong, the presentation is still a bit busy and long. The paper can go to publication. 

  

Author Response

Thanks for your kind suggestions, which are valuable for improving the manuscript. We improved the figures to be of better quality.

Author Response File: Author Response.docx

Reviewer 2 Report

Unfortunately, the authors' responses to my first-round concerns are not convincing, and I still believe that there is nothing original and innovative analysis in the manuscript. Therefore, I can't recommend it to be published in this Journal. To tackle the originality problem, the authors added multidimensional scaling method (MDS) results which is a rudimentary method. For my second comment, the authors stated that there are now records after 2010. If so, what are the benefits of your findings for the future of the catchment? The introduction is not to the point yet and no review was done on trend analyzing studies. Overall, this manuscript only applied the basic and linear trend analyzing methods for some closed stations (as the authors claimed), knowing that the use of Man-Kendall and MDS trend analyzing is not something novel. 

Author Response

Review 2

Unfortunately, the authors' responses to my first-round concerns are not convincing, and I still believe that there is nothing original and innovative analysis in the manuscript. Therefore, I can't recommend it to be published in this Journal. To tackle the originality problem, the authors added multidimensional scaling method (MDS) results which is a rudimentary method.

- We agree with the reviewer that the linear regression method and MK trend are not new. A novelty is the use of a multidimensional scaling method to compare trends using Z and sen Slop for parameters such as air temperature, precipitation and flow. Thanks to this, we obtained additional relationships within the analyzed trends. We got to know the patterns of changes that occur in the area of individual sub-catchments, and which did not result from the single analysis.

For my second comment, the authors stated that there are now records after 2010. If so, what are the benefits of your findings for the future of the catchment?

- In response to reviews1 we wrote ‘The presented studies cover the period for which hydrological data were available’. We did not write that we have data from 2011 to 2020, if we had such data, the calculations would be made from 1961 to 2020.

The introduction is not to the point yet and no review was done on trend analyzing studies. Overall, this manuscript only applied the basic and linear trend analyzing methods for some closed stations (as the authors claimed), knowing that the use of Man-Kendall and MDS trend analyzing is not something novel. 

-We revised the introduction and added new references. The applied research procedure of using the multidimensional scaling method to compare the trends of precipitation, air temperature and flows is new.

 

 

Author Response File: Author Response.docx