SNR-Based Water Height Retrieval in Rivers: Application to High Amplitude Asymmetric Tides in the Garonne River

Round 1

Reviewer 1 Report

The dynamic SNR method was proposed for dealing with data from GNSS-IR to retrieve water heights on a river with high changing rate. The unbiased root mean square deviation was small after filtering out the noise. I would like to recommend the manuscript be accepted for publication after some revisions. Specific comments are listed as follows:

1. L40: "..own-looking..." should be "..down-looking...".
2. L123 - 124: Why the azimuthal range isn't constrained in -45 ~ 150 degrees instead of 10 ~ 150 degrees? It is possible to increase the number of satellites.
3. Fig. 1: The longitude is usually captioned as 'W' instead of 'O'.
4. Section 2.3: To illustrate the accuracy of the validation data, the authors should extract some items from the specification of the pressure transducer.
5. Section 3.1: Because the SNR is very important in this study, please illustrate the definition of SNR with formula.
6. Figure 3: This figure is fundamental to this article but it isn't referred to in any part of the article. Authors should add description for it.
7. Figure 3(b) and (c): The size of captions for vertical and horizontal axes is too small to read. Furthermore, the units are absent.
8. Table 1:

(1) The caption shows that there are green and red rows in the table, but I can’t find any.

(2) Maximum errors are important too and they should be calculated and listed in the table.

9. Fig. 5(a): Maximum errors for water heights by utilizing SNR L1, L2, and L1/L2/L5 reached about 2 m, Authors should discuss the matter.
10. Fig. 5(a) and the 2nd paragraph in Sec. 5.2:

(1) Why sometimes the maximum error by using SNR L1/L2/L5 is larger than that of SNR L1? e.g. the water height data on 18:00 ~ 19:00.

(2) Authors should discuss the benefit of using multi-frequency signals.

11. Fig. 5(b): In the rising and falling stage of water height, dh/dt should be positive and negative, respectively.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper a very interesting theme of remote sensing technology with potential applications to water height measurements in rivers was described. The Garonne River was chosen as a very demanding narrow area with an asymmetric tide, a high range of tidal oscillations (≈ 6 m) and vegetation on the river banks.

The results of this paper are promising and may lead to new results in estimating the spatial and temporal variability of water height of rivers.

The construction of the paper is good and correct. The suggestions bellow have the purpose to contribute with the authors.

My general comments and suggestions are as follows:

1. Page 3. Line 115. The value ˃ 1 m.s^-1 should be ˃ 1 mm.s^-1 !?
2. Paragraph between lines 116 and 118 should be supplemented with:
3. a) a picture showing the oscillations of the water level over a period of 1 month, so that the characteristics of the tidal oscillations are seen in more detail;
4. b) a photo showing tidal bores (if any).

My recommendation is that minor revision is necessary.

Author Response

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Author Response File: Author Response.pdf