Mid-Term Monitoring of Suspended Sediment Plumes of Greek Rivers Using Moderate Resolution Imaging Spectroradiometer (MODIS) Imagery
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript presents the development of a sediment productivity index aiming to monitor riverine sediment discharge of 17 Greek rivers in their receiving basin. The approach is based on the elaboration of MODIS imagery and is supported by hydrological modeling. The study is interesting enough, supported by a rich dataset and the methodologies used have numerous strengths, sufficient to argue for paper publication.
However, I believe that there are some points that have to be addressed in order to strengthen paper's quality and its scientific resonance.
Many comments will be found within the commented text. In the following lines, I summarise a list of the main points of the manuscript in its current form, focusing on both structuring and scientific interpretation:
· In the introduction section I miss a paragraph reviewing in brief: (i) Modis applications in coastal riverine environments and (ii) other existing remote sensing approaches in the same environment. In general, I think that Introduction should be more focused on reviewing mechanisms in these environments, along with summarizing relative works and approaches used for the same scope.
· Moreover, it would be an advance to justify why you work with MODIS images instead of other imagery (eg. Sentinel...): what are the advantages and what are the shortcomings of using MODIS (eg. low resolution)?
· The discussion section is missing. I propose to convert Results Section to Results and Discussion, as commentation is already being carried out in this part.
I have some doubts in relation to the interpretation of the results and in some cases to the presence of generalities in the discussion. It is a fact that the high number of the under-investigation systems prevents case-by-case validation of the outputs. However, considering that the paper has strong results and adequate relative background literature exists, linkage between remote sensing outputs and scientific interpretation can be reached. Some comments and hints are provided in comments within the text.
· Last, there are some wording and meaning issues that have to be addressed. Some of them have been indicatively highlighted and commented, yet, authors are encouraged to go through the text and make corrections.
Comments for author File: 
Comments.pdf
Author Response
Attached you can find our point to point response to your comments and suggestions.
sincerely
E. Karymbalis
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsAuthors used MODIS datasets to monitor the suspended sediment plumes of Greek rivers. different models were applied to retrieve the suspended sediment plumes. In their results, BQART model could provide information on the catchment's sink capacity. Finally, their results using remote sensing was compared with soil loss models. Generally, this work is good, with good english writting, good novelty. Before publication, several minor comments might be useful for authors.
Figures: all figures in this manuscript had low dpi, suggest authors to improve your figures' dpi.
Suggest authors to redraw Figure 2, especially the figure 2(b), it seems that authors just used the screenshot figure in ENVI software, authors should carefully treat this situation.
In addition, in this manuscript, authors don't have the discussion part. Discussion is very important, The section of Discussion in a paper is generally involved with 3 or 4 parts: (1) main points, which response to the questions put in introduction; (2) comments on related studies or problems; (3) shortcomings or deficiency in study method or process; (4) conclusions, which can be separated to make the final section.
In authors manuscript, section 4.2 is more suitable in Discussion part. The title of section 4.1 needs to more specific. Remote sensing is too general.
After these minor modifications, this manuscript could be published.
Author Response
Attached you can find our point to point response to your comments and suggestions.
sincerely
E. Karymbalis
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe changes in suspended sediment concentration are assessed by two MODIS products. For this aim, 669 daily MODIS data including flood events is evaluated for 10 annual periods. Then, suspended matter index is developed in the paper. The subject is very important and the study is valuable in terms of the observation of suspended sediment in the river basins but the novelty of the study is emphasized insufficiently. Some suggestions and comments to the authors are presented below:
1. The flowchart of the suggested methodology should be given by more branches and in detail in Figure 3. Thus, the readers can easily follow the application procedures.
2. Some legends on the figures & maps should be presented better and live colours. Also, there are missing or wrong legends on the maps as country border, etc. See Figure 1 … North arrow should be added to the maps.
3. Conclusions part can be improved in the paper. Here is presented in a general concept.
4. What is the novelty of the paper? Other sediment matter indices as NDSSI, NSMI, NDWI, etc. are explained in the paper. Supported and related studies should be strongly presented in the paper by emphasizing the novelty of the paper.
5. Discussions part is missing in the paper. Also, literature part is looking weak. Give new and last updated examples from literature about “suspended sediment” as
10.3390/s16081298
10.54740/ros.2022.016
6. Is the suggested methodology in the paper valid for all areas or is there any limitation, difficulty or classification for the application?
7. As one important step of the study, the statistical characteristics of used data (e.g. suspended sediment data) should be presented in detail. The statistical properties as skewness, coefficient of variation, confidence intervals, distribution characteristics, min, max and median, etc. of used data should be given in a table.
8. The performance metrics part is weak in the paper, Figure 4 is presented for the three of river plumes. More metrics can be calculated to evaluate the application results NSE, RSR (Ratio of RMSE to the standard deviation of the observations) etc. …
9. The resolution of the spatial maps & figures can be increased.
Comments on the Quality of English LanguageCheck the tenses of the sentences. There are present and past tenses in a paragraph. See the paragraph in the Abstract.
There are some crucial errors.
Keywords should be ordered from A to Z.
Use passive sentences. Check the sentences starting with “we”. See the line 124 …
The direction names should be started by capital letters such as Northwest, Southeast …
Author Response
Attached you can find our point to point response to your comments and suggestions.
sincerely
E. Karymbalis
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsEven though this is an interesting study, it could be useful to understand sediment delivery ratio as a catchment's properties. However, the article needs some revisions. Please address the comments to improve the quality of your article.
1. The introduction also needs improvement. For example, in the introduction line 49-50, authors stated that "...tectonic conditions, the size of the floodplains, and the hydrodynamic characteristics...". I suggest that the authors provide the following reference to support the argument: Sarker, S. (2023). Separation of Floodplain Flow and Bankfull Discharge: Application of 1D Momentum Equation Solver and MIKE 21C. CivilEng, 4(3), 933-948. Again, in the line 82-83, authors stated that "...Streams are the primary agents of transfer of erosion materials...". I suggest that the authors provide the following references to support the argument: (a) Singh, Arvind, et al. "Experimental evidence for statistical scaling and intermittency in sediment transport rates." Journal of Geophysical Research: Earth Surface 114.F1 (2009), (b) Gao, Yuan, et al. "Analyzing the critical locations in response of constructed and planned dams on the Mekong River Basin for environmental integrity." Environmental Research Communications 4.10 (2022): 101001. In addition, in the line 60-61, authors stated that "... regimes, and the hydrophysical, geomorphological, and ecological functioning...". I suggest that the authors provide the following reference to support the argument: Sarker, S., Sarker, T., Leta, O. T., Raihan, S. U., Khan, I., & Ahmed, N. (2023). Understanding the Planform Complexity and Morphodynamic Properties of Brahmaputra River in Bangladesh: Protection and Exploitation of Riparian Areas. Water, 15(7), 1384.
2. Figures 1 require revision. On the map of their study area, authors may include DEM, river networks and systems. Please review the manual for ArcGIS or another professional software in order to generate publication-quality figures. Additionally, figures 2, 4, 6, and 9 need substantial revision. Again, review the ArcGIS manual in order to produce figures suitable for publication.
3. Figure 5, 7, and 8 require extensive revision. Authors may use Python or Matlab to generate publishable figures. Reduce the space between subplots. Please review this python toolbox. https://timcera.bitbucket.io/plottoolbox/docs/index.html
4. I am not convinced by the writing in Methods! Currently, it is poorly written! Please review additional articles to improve your methodology. Also replace figure 3 with a nice and clean flow chart.
5. Can you provide a statistical comparison between observed sediment transport and the index you developed? How else could you be sure that the index accurately quantifies the phenomenon?
6. What is the significance of this research? Please explain this study's implications in terms of environmental protection and climate change. Please describe the potential implications of this study in a separate section (prior to the conclusion). It does not currently convince me that it provides a foundation for environmental protection and climate change.
Comments on the Quality of English LanguagePerhaps it would be beneficial for the authors to revise their compositions, particularly the sentence structure.
Author Response
Attached you can find our point to point response to your comments and suggestions.
sincerely
E. Karymbalis
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsI suggest accepting the manuscript. The authors carefully revised the paper by answering each comment from the first round.
Reviewer 4 Report
Comments and Suggestions for AuthorsThanks for the revision.
Comments on the Quality of English LanguageDouble check again.
