Monitoring Lake Volume Variation from Space Using Satellite Observations—A Case Study in Thac Mo Reservoir (Vietnam)

Round 1

Reviewer 1 Report

In this manuscript the authors proposed a workflow for estimating monthly variation of surface water volume of Thac Mo reservoir using S1-2 and Jason 3 data. The manuscript is concise and offers a good explanation of concepts. The structure is clear and easy to grasp. However, in my opinion, this manuscript lacks innovation. The methods used for extracting the information are classical models. I do not think if this manuscript should be accepted, but if other reviewers differ, I would not oppose strongly.

-- One of the main reasons which the extracted extends are not accurate is the model used for extracting the extends. There are more advanced models for instance SVM or MLP or Deep learning models (Res Net, Res UNet). I suggest the authors to try them in order to increase the accuracy of their estimation. I am providing this paper for your perusal:

https://doi.org/10.3390/w8110478

https://doi.org/10.3390/rs13204121

https://doi.org/10.3390/rs13020197

https://doi.org/10.3390/rs12244140

https://doi.org/10.3390/rs13132498

-- For the minor comments please refer to the pdf file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is concerned with monthly estimation of water volume variations of the lake Thac Mo using data from the Jason-3 altimetry and Sentinel-1 imagery. Altimetric data is used to estimate variations in the surface water level, and SAR image for water surface estensions. Results are consistent with concurrent measurements from optical images gathered by Sentinel-2 and in situ measurements.

The paper is well written, with comprehensive description of the methodology used, which also includes  information taken by external databases. A detailed analysis of the results is then presented and discussed with limits and advantages of the employed tools.

I do not have any further comments.

Author Response

Dear reviewer, 

We would like to thank you for spending your time to evaluate our manuscript. 

Yours sincerely, 

On behalf of all co-authors, 

The corresponding author. 

Dr. Binh Pham-Duc

Author Response File: Author Response.docx

Reviewer 3 Report

To the reviewer, this research study is an improved version over Frappart et al. (2006) substantially, perhaps owing to the improvement of data quality. Apparently, the statistics and the estimated time series are consistent with that of in situ data. However, major revision has to be made [in particular literature on monsoon and ENSO impact on water level, water extent, etc].

Major comments:

The time span is around 6-7 years. The mekong is subject to Western North Pacific monsoon and Indian Summer monsoon along with ENSO. So, the introduction and discussion might have missed 1-2 paragraph(s) for discussing the potential remaining discrepancies. You might read the below reference for understanding the monsoon and ENSO. Please write your own understanding in the introduction and discuss the potential remaining discrepancies in the result and discussion.

Reference:

Fok, H. S., He, Q., Chun, K. P., Zhou, Z., & Chu, T. (2018). Application of ENSO and drought indices for water level reconstruction and prediction: A case study in the lower Mekong River estuary. Water, 10(1), 58.

Li, T., Wang, B., 2005. A review on the western North Pacific monsoon: Synoptic-to-interannual variabilities. Terrestrial Atmospheric and Oceanic Sciences 16, 285-314

Wang, B., Wu, R.G., Lau, K.M., 2001. Interannual variability of the Asian summer monsoon: Contrasts between the Indian and the western North Pacific-east Asian monsoons. Journal of Climate 14, 4073-4090.

Chang, C. H., Lee, H., Kim, D., Hwang, E., Hossain, F., Chishtie, F., ... & Basnayake, S. (2020). Hindcast and forecast of daily inundation extents using satellite SAR and altimetry data with rotated empirical orthogonal function analysis: Case study in Tonle Sap Lake Floodplain. Remote Sensing of Environment, 241, 111732.

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear authors,

Thanks for your response. However, still I do not think if this manuscript should be accepted (my previous comments), but if other reviewers differ, I would not oppose strongly.