Water Levels in the Major Reservoirs of the Nile River Basin—A Comparison of SENTINEL with Satellite Altimetry Data
Round 1
Reviewer 1 Report
A simple and direct article on the application of various types of satellite data (Sentinel 1, Sentinel 2, ....) in their application for the control of the water level of different reservoirs, located along the Nile River. The paper fits perfectly into a magazine like Remote Sensing. The paper can be published after minor corrections or suggestions.
Title: Very methodological title. I propose: Water levels derived from the main reservoirs of the Nile river basin: comparison of SENTINEL with satellite altimetry data
Line 15: GERD?
Line 40-42: Has there ever been an international program to control river levels or reservoirs in the Nile or another of the great transboundary rivers? The UN or another organization (FAO, UNESCO, World Bank, ...)
Lines 99-102: I don't think this paragraph is necessary. People who read the RS papers already know the different sections.
Lines 164-165: Add to the foot of the figure the source from which the map has been made.
Line 249: It would be possible to make a graph between the values. It would be very visual and not just give specific data or other statistical data.
Line 252: Note???
Line 263: Delete (a), similar to line 281 and to line 303.
Line 285: Attention! The data in Table 2 is for Lake Naser, not Lake Merowe.
Line 309: Table 3!!! Data from lake Merowe!!!
Lines 311-322: This section 3.2, would not be better in Discussion?
Line 315: The name of GERD or the Millennium Reservoir must be homogenized throughout the entire paper. I personally believe that the work is about the Millennium Reservoir, which is generated by the construction of the GERD.
Lines 340-344: Would this explanation about SWOT be better in the Introduction?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Manuscript: Comparison of SENTINEL Derived Water Levels with Satellite Altimetry Data for Major Reservoirs in the Nile River Basin
The manuscript is very interesting. Its objective is to provide a comparison of the reservoir surface water extent and water level estimation process using satellite imagery using data from Sentinel-1 with Sentinel-2, and satellite altimetry data, respectively.
Here are my comments:
96-98 To promote public usability of the research, we use the open-source coding language (Python) to analyze the SAR images as well as for analyzing the results and the codes will be publicly available through GitHub.
Comment: Please add the name the link of the code using in the study.
118-119 Rainfall over the reservoir is sparse with an annual average amount of 85 mm.
Comment: Could you please add a figure of monthly rainfall times series over the region of lake Nasser.
136 In addition, it receives less than 20 mm of annual rainfall
Comment: Could you please add a figure of monthly rainfall times series over the region of Merowe Reservoir.
148 The region receives 700 mm of annual rainfall
Comment: Could you please add a figure of monthly rainfall times series over the region of Roseires Reservoir.
156 The region receives on average 550 mm of annual rainfall
Comment: Could you please add a figure of monthly rainfall times series over the region of Millenium Reservoir.
168-139 In this study, we used a combination of Synthetic Aperture Radar (SAR) Sentinel-1and optical Sentinel-2 imagery.
Comment: Please add the link of the datasets used.
Comment: For Table 1, please change the caption to the upper part of the Table.
270 For Lake Merowe, Figure 4 and Table 2 shows the water level estimated using Sentinel along with G-REALM altimetry data
Comment: Please replace the content of Table 2 and Table 3 with their titles and correct them in the text.
Comment: Do you have any reported ground-based water level measurements for comparison and validation.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The evaluation technic from the satellite altimetry data will be useful to make the water distribution plan in the international joint committees.
Several Review Comments are follows;
1) The maps are very clear and beautiful, is possible, please write down (Distance Scale) at each map in Fig.2.
2) Figure 4; Sentinel-data has more than 5m scattering. Please add more detail explanation about the mismatch of the Sentinel-data.
3) Figure 6; The Nasser and Roseires have similar tendency in the variation of “height variation” Meanwhile, the curve of the Merowa basin is differ from the other two basins. Why does the tendency of Merowa variation have the different one from the Nasser’s and Roseires’s?
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
The content of the article is not particularly innovative, but it is satisfactorily presented and processed.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear Authors,
Please check the reservoir names in the first column and the table titles for Lake Merowe and Lake Nasser.
Best regards.
Author Response
Response: Thank you for pointing that out. The names have been corrected. The authors appreciate your feedback, comments and suggestions in improving the manuscript.
Changes in manuscript: [Line 309]: Lake Merowe
[Line 344]: Lake Nasser
