Sustainable Coastal Evolution and Critical Sediment Load Estimation in the Yellow River Delta

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The references used to highlight what has already been studied on the subject present a very good rate of recent material (56% from the last 5 years) with 34% of articles reviewed between 2005 and 2020, evidencing the concern in presenting an updated manuscript to the scientific community.

Since the manuscript works with sediment discharge data by area of ​​the Yellow River Delta, a more detailed statistical analysis of the data is missing to ensure confirmation of what was concluded in the work. In the conclusions, the authors comment "The coastline of the Yellow River Delta has exhibited pronounced long-term variability and instability.". If there is a pronounced variability, how was this detected if there is no statistical analysis presented in detail in the manuscript?

Minor observations:
Some passages have long sentences that could be divided to improve the flow of reading.

The use of expressions such as “et al.” in “...and et al.” could be reviewed, since “et al.” is not preceded by “and” (the correct form would be just “et al.”).

There are repetitive terms that could be softened with lexical variation in some passages.

I believe that implementing or presenting a statistical analysis of the data processed in the manuscript could guarantee its publication in the Sustainability Journal. I recommend a minor revision.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript uses satellite imagery to extract shoreline change along multiple estuaries of the Yellow River Delta and places the results into the context of sediment delivery and diversions. The manuscript is well written and provides a data driven and clear synthesis of shoreline change along 3 different estuaries. I believe there is an opportunity to improve the methods to better explain the “water frequency” approach so that it is clearer and reproducible. Please see the comments below for specific recommendations to clarify the methods:

I feel like the first sentence should be something more general – i.e., something about delta sediment dynamics and how that relates to coastal management – then go into the specifics about the Yellow River delta

Line 70 – “water frequency” (and throughout) – Is this persistent water presence?  -- I feel like this metric needs a more detailed name.

Remote sensing data – provide resolution information/frequency of Landsat/Sentinel imagery

How are coastlines extracted from grouped images? I.e., if shoreline locations change between images in a group – how is the shoreline determined? Is the shoreline a composite of all images in the group? How is that accomplished?

Line 168 – “high-frequency water” – what is the threshold (I see this is described later in the text (i.e., line 204, but I think it should be introduced here as well). I think it would be appropriate to include a descriptor that says high water levels determined through frequency analysis when this is first introduced.

Line 187 – “..the water during high tide is extracted…” – Again I see this is defined later – but I think it would be useful to introduce the description earlier – also, is tidal information verified in any way? For example, are imagery time stamps compared with a nearby tidal gauge?  

Line 192 – what is a “good observation” and how does it differ from the number of images?

Line 217-218 –Is shoreline complexity not relevant to this analysis? – If not, I don’t think it needs to be included. Also, I think the same can be true for NSM – I would recommend saying that LRR, EPR were used to assess shoreline change because they can address non-uniform temporal intervals. You could include a brief paragraph on these other methods in the discussion for comparison, but I don’t think they are necessary in the methods if they are unused.

Line 237 – how long were the transects?

Line 238 – “..from north to south” – doesn’t this depend on the shoreline orientation? Unless the shoreline is always oriented from east to west?

Table 2 – what is the difference in the “Average EPR columns” and why are there no values for Diaokou and Qingshuigou estuaries in the last column?

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Comments - Questions (to be clarified in the text):

1. Line 129: What is GEE?
2. Equation (2): According to the mathematical definition of WF, it should obtain values greater then one.
3. Line 199: Which is the difference between intra-cluster and inter-cluster similarity?
4. Section 4.2 and Sub-section 4.2.1 have the same title.
5. Figures 11a and 11b: The x-axis should be checked: (a) Is the scale of the x-axis logarithmic? (b) Is the x-axis expressed in 10⁸ t? (c) Where exactly lie the values 0.79 billion t/a and 0.107 billion t/a?
6. See annotated manuscript!

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Some corrections are annotated on the manuscript.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Comments:

1. Figure 11a: The regression line intersects the x-axis in a point with x-value between 1 and 2 (x10⁸).
2. Figure 11b: The regression line intersects the x-axis (y=0) in a point with x-value about 1.6(x10⁸).
3. See annotated manuscript for editorial errors!

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf