Research on Water Content Spatial Distribution Pattern of Fine—Grained Sediments in Debris Flow—Taking Beichuan Debris Flow as a Case

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

1. INTRODUCTION

- LINES 50-71: It is necessary to revise the englishl anguage. In fact, from line 50 to line 71 there is only a long and confused speech. So, it is better to split this long paragraph into many short sentences. In this way, the content of the paragraph could be more readable and intellegible.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer and Editor:

Thanks for your comments and suggestions.

We have revised our manuscript and highlighted the changes using the track changes mode in MS Word.

To show line/page numbers correct, please see the file by “Simple Mark View” mode on the Review board/menu in MS Word.

Please see our responses in the attachment!

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 5)

Comments and Suggestions for Authors

The graphics of Figure 1 are now improved, although the right inset is still not very useful, especially because it does not show the position of the Sichuan Province in China. The introduction of Figure 2 is good, perhaps the information contained in the left inset of Figure 1 (isohypse) could be transferred to Figure 2, leaving more space for the right inset of Figure 1 and the insertion of another map showing the position of Sichuan Province in China. In figure 2 it is not clear where SP08 is and there are more points than labels.

It would be important to try to discuss the causes of the variability of the measured data, whether it is due to an error due to the characteristics of the instruments or the measurement methodology, or whether it is "intrinsic" to the place from which the samples were extracted. This is important to discuss the list of standard deviations shown in Table 3.

Table 3 shows results with 7 significant figures for the mean values. It seems to me that they are a bit too many, I do not think it is possible to determine the mean with such high precision. Even for the standard deviation, 3 significant figures seem too many to me.

In the penultimate line, you report 0 as the value of the standard deviation. How is this possible? Do you mean the standard deviation of the population or the mean (usually called "standard error")? Please clarify this point.

Why don't you report the standard error associated with the means in Figures 4 and 5 (in the form of error bars)? This would improve the interpretation of the data, in particular of the regressions shown in Figures 4 and 5, allowing the estimation of the errors on the parameters and the construction of confidence bands, which are indicators of the goodness of a fit, better than the R^2 and the p-values ​​of the coefficients. In any case, I believe that the variable "sampling point" (which is an integer increasing from upstream to downstream) is not a correct variable to use, also because the sampling points are not equally spaced, and are crowded (SP07-SP11) in a region where the trend of the average water content is not always increasing (decreasing from SP9 to SP12).

The methodology developed to simulate the calculation of the correlation coefficient of the regression line between the average cohesion (or shear strength?) and the water content as a function of the normal stress is not clear. What value (or values) did you use for the internal friction angle? Did you fit the data shown in Figure 5 by reworking them in some way? If yes, how?

How much do you expect the value R=0.56 that you obtain for the hypothesis sigma=0 to vary if it were possible to repeat your experiment?

This is important to understand whether a variation of R that at most reaches 10% can be significantly attributed to an effect of normal stress rather than simply being a consequence of the randomness of R. I understand that Figure 6 is obtained by finding different models of fit for the same data, but it is not clear how the value of 80kPa for which the maximum R is obtained (therefore the "best" fit) can constitute a threshold, given that none of the quantities shown have a "jump" or a sudden variation.

Comments on the Quality of English Language

Minor editing of the English language is required.

Author Response

Dear Reviewer and Editor:

Thanks for your comments and suggestions.

We have revised our manuscript and highlighted the changes using the track changes mode in MS Word.

To show line/page numbers correct, please see the file by “Simple Mark View” mode on the Review board/menu in MS Word.

Please see our responses in the attachment!

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The manuscript “Research on Water Content Spatial Distribution Pattern of Fine-grained Sediments in Debris Flow - Taking Beichuan Debris Flow as a case” studies the spatial distribution pattern of water content and establish the correlation between water content and shear strength of fine-grained sediments to provide scientific basis for debris flow hazard prevention. This research has certain scientific significance and practical value.

Some detailed suggestions are as follows.

1. Abstract: The description of fine-grained sediment background is vague and inconsistent. For example, water content and shear strength are key inter-controlled factors of fine-grained sediments stability, why is this important for early warning of mudslide disasters?

2. Please add the figures of test equipment and test procedure.

3. Shear strength was measured using the ZJ strain-controlled direct shear instrument with the controlled shear rate between 0.02 and 2.4 mm/min. How is it set up during operation? Is it a specific shear rate or different shear rates?

4. Figure 5 and figure 6 respectively represent the effect of mean cohesion and normal stress on the mean water content in unsaturated fine-grained sediments. However, the effect of internal friction angle on the average water content in unsaturated fine-grained sediments is not discussed. It is recommended that the effect of internal friction angle on the average water content can be added in unsaturated fine-grained sediments.

5. In the unsaturated state, as shown in figure 5, the correlation coefficient is 0.56, the standard deviation is 2.63, and X variable’s P-value is 0.03, where is it possible to demonstrate a significant correlation between mean cohesion and mean moisture content at more than 95% confidence level?

6. The summary in the conclusions is complex, and it is recommended that the authors streamline the second conclusion.

Author Response

Dear Reviewer and Editor:

Thanks for your comments and suggestions.

We have revised our manuscript and highlighted the changes using the track changes mode in MS Word.

To show line/page numbers correct, please see the file by “Simple Mark View” mode on the Review board/menu in MS Word.

Please see our responses in the attachment!

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (Previous Reviewer 5)

Comments and Suggestions for Authors

Point 1

In Figure 1, it is still unclear where Sichuan is in China. No problem, those who want to understand will look for this information elsewhere. In the legend, write "Provinces" and not "Provines"

Point 2

Make sure you have inserted somewhere in the article the sentence

"The causes of the variability of the measured data are "intrinsic" to the place from which the samples were extracted. Because water content, grain size and shear strength are tested using standard instruments with corresponding measurement methodology, results of tested Cohesion, Permeability Coefficient from the same experiment are published in [39] and in [41]."

Point 3/4

I approve the correction to Table 3. It would be good to explain in the article why for SP14 you have only 1 sample while, for the other points, there are, on average, about 13.

Point 5

It would be good to explain in the article, not only to the reviewer, why you do not think it is important to show the error in Figure 8.

Points 6/7

I still think that your explanation is rather obscure. In any case, insert in the paper the sentence

"We believe that the normal stress thresholds are different at other sites, which can be determined by the same methodology as that used in Section 4 of this manuscript."

after the 1st Para after Figure 9, P12.

Author Response

Thank you for your comments and suggestions.

We have revised our manuscript and highlighted the changes using the track changes mode in MS Word.

To show line/page numbers correct, please see the file by “Simple Mark View” mode on the Review board/menu in MS Word.

Please see them in the attachment!

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper needs to be systematically revised before review.

Comments on the Quality of English Language

No

Author Response

Please check attached file: 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please, see the attacched file. 

Comments for author File: Comments.pdf

Author Response

Please check the attached file:

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article titled “Research on Water Content Spatial Distribution Pattern of Fine-grained Sediments in Debris Flow - Taking Beichuan Debris Flow as a case” aims to spatially detect the danger posed by light materials in the debris flow.

Although the title of the Manuscript is not a scientific title, there are serious shortcomings in the Manuscript.

First of all, the Manuscript's methodology is not well explained. Only how the samples were collected and how they were baked is included.

For example, where was remote sensing data used? How was it used?

If this is a project paper, it needs to have more analysis.

The results of the data are hardly interpreted and not well presented.

As a result, I have to reject this Manuscript. Since there are serious problems at the core of the article, I do not feel the need to make formal and design criticisms.

I think the authors should re-edit this work and upload it as a new article.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The overall aspect/nature of the study is not novel enough to be considered as novel for publication. The results presented are already well established in the literature. Hence, the paper is not recommended for publication. 

Comments on the Quality of English Language

Minor

Author Response

Please check the attached file:

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The topic of this work is very interesting, but the paper needs a thorough revision before it can be accepted.

Let's start with the geological framework. The description of the strata on lines 90-96 of page 2 is crucial and should be more than a simple list. Do you have any additional information? Can you show a geological map of the area?

Figure 1 on the left is too small, SPs 7 to 11 are not easily identifiable, and the contour lines (isohypses) are not visible. I suggest you completely rethink this Figure. Perhaps it would even be preferable to organize three different scales: one for the study area, one that places the study area in the Sichuan province and the last one that places the Sichuan province in China.

Let's move on to the data and the description of the equipment used.

It would be crucial to provide some information on the precision and sensitivity associated with each of the instruments used, also in anticipation of the discussion of the measurements taken. If I am not mistaken, this information is now provided only for the images provided by the remote sensing system (Table 2, with many incomplete columns...).

The sampling description is limited to a long list of images. It would be preferable to include a table (or a graph) that allows you to establish the criteria that led to the classification that is stated in the various descriptions ("hardened silty loam", "loose silty loam", "loose-hardened silty loam", "hardened-loose silty loam").

A summary table of the water content (average?) and the average grain size (average?) would be very useful.

Since you state that you collected 13 samples (approximately) for each of the chosen sampling points, it is clear that it is possible to obtain information not only on the average value of the quantities you measured but also on their dispersion. Why did you not also report the standard deviations of the measurements you performed? Do you have an idea of ​​the influence that the precision/accuracy of the instruments you used to perform the measurements may have had on the dispersion of the measurements themselves? The standard error on the means could be a column to add to the tables that I propose to insert.

I conclude with the section in which the results are described and commented.

Also in this case, the standard errors (error bars) shown in Figures 2 and 3 are not reported in the graphs. It is not clear whether Figure 4 is the result of a series of measurements (or simulations) or instead of a theoretical model. In any case, the label on the abscissa axis ("Normal stress") seems to disagree with what is written in the caption ("shear strength"), furthermore, there is no dotted line drawn that could indicate a trend...

The statistical analysis of the data obtained from the experimental measurements is very lacking. In Figure 2 you have the sample number as a "variable" on the abscissa. Even though I understand that the samples are numbered progressively following the river, I don't understand how it is possible to consider this number as a variable. Perhaps it would be better to use a sort of "curvilinear abscissa" along the course of the river or use a more quantitative variable such as longitude or altitude.

The linear correlation shown in Figure 3 also needs a more in-depth explanation. Without an indication of the standard errors, it is not easy to understand if some points are outliers if the linear model is incorrect or too simple, and how "statistically reliable" are the slope and intercept values ​​​ you report (they are also associated with an error). The correlation can be evaluated in many ways, and I think it is right to choose the model after careful analysis, instead of simply writing a number (0.56) that could be very different if the experiment were repeated in its entirety.

The same goes for the choice of R as an indicator to decide between two different physical behaviours. Apart from the fact that the variation of R is not as marked as Figure 4 would suggest (a maximum difference of 0.06 on a maximum value of 0.6, i.e. 10%), there is the problem that from your analysis it is not clear how reliable the values ​​of R that you obtain from your regressions can be. An uncertainty of 10% on the value of R obtained (remember that R is also a random variable!!) nullifies all the efforts undertaken to develop a model between the shear stress and the value of R. In any case, it would be important to show (at least in a table) some examples of coupling between the shear stress and the value of R obtained from the regression, since it does not seem to me that the values ​​reported in Figure 4 are an experimental result (they are very regular...).

In summary, please be a little more careful in the presentation of the data and their discussion. The topic you address is very interesting, and it is not nice to see it treated too lightly.

Comments on the Quality of English Language

Minor editing of the English language is required (in the next review).

Author Response

Please check the attached file:

Author Response File: Author Response.pdf