Debris Flow Susceptibility Assessment Using the Integrated Random Forest Based Steady-State Infinite Slope Method: A Case Study in Changbai Mountain, China

Round 1

Reviewer 1 Report

The manuscript introduces an attempt to integrate two well-known landslide susceptibility assessment methods (i.e. the Random-Forest and the Steady State Infinite Slope ones) to improve their prediction ability of debris-flow occurrence in a volcanic landscape of the Jilin Province, China. The manuscript has been largely improved by the Authors and the current version can be suitable for publication after a moderate revision.  Although most of the problematic aspects of the paper have been clarified and improved, I think that the following minor issues should be better introduced and discussed in the manuscript: i) I do not agree with several statements about limitations and advantages of the SSIS deterministic approach. For example, the Authors stated that “SSIS method only takes into account the cumulated drainage area and the slope factors in to calculations, and neglect the influence of real terrain to debris flow, making incomplete and inappropriate results with respect to the actual situation”. Indeed, a correct and accurate definition of the spatial distribution of soil parameters (i.e. cohesion, internal friction angle, hydraulic conductivity) should allow to fully characterize the slope stability index. Of course, this purpose is hard to achieve but in an ideal situation a well-constrained deterministic model should be able to describe the stability factor of a study area. In other words, I think that the low ability of a deterministic model of landslide susceptibility is simply due to the difficulty/inability to define the accurate values of soil parameters. This issue and the usefulness of the introduction of heuristic/probabilistic models to improve the prediction ability of the SSIS method should be better explained in the discussion section. The Authors can also include the following references about the relationships between landslide occurrence, susceptibility assessment  and lithological/topographical factors: a) Lazzari & Gioia (2016) - Regional-scale landslide inventory, central-western sector of the Basilicata region (Southern Apennines, Italy). Journal of Maps 12, 852-859; b) Lazzari, et al. (2018) - Landslide inventory of the Basilicata region (Southern Italy). Journal of Maps 14, 348-356.  

 

Moreover, the following minor amendments and corrections should be done:

Page 1 Line 41: please change “popular” with “urbanized”.

Page 1 Line 42: Please change “characteristics and reasons for” with “predisposing and triggering factors of”  

Page 2 Line 44: Please add “spatial and temporal” after the word “its”.

Page 2 Lines 105-108: not clear. Please modify the sentence.

Page 9 Line 223: Please delete “and” after the word “method”.

Page 9 Line 228: What is the meaning of “source material map”?

Page 9 Line 236: Please change “model” with “models”.

Page 13 Line 351: Please correct “Pperating”.

Page 13 Line 372: Please change “gully” with “gullies”.

Page 18 Line 504: Please change “an” with “a”.

Author Response

No.: Water-858502

 

Title: Debris Flow Susceptibility Assessment Using the Integrated Random Forest based Steady-State Infinite Slope Method: A Case Study in Changbai Mountain, China

 

Journal: Water

 

 

Dear Editor and Reviewers:

Thank you very much for your valuable suggestions and comments on my manuscript.

Your suggestions and comments are of great assistance for improving and revising our manuscript, to make it acceptable for publication in Water.

 

I have tried to revise and improve the manuscript in line with the suggestions made by you and other reviewers.

 

Detailed corrections are listed below point by point.

 

Responses to Reviewer 1’s Comments

 

 

Although most of the problematic aspects of the paper have been clarified and improved, I think that the following minor issues should be better introduced and discussed in the manuscript.

 

Thanks for your valuable comments on our paper. Your comments are of great assistance to us for improving and revising our manuscript so as to be acceptable for publication in Water. We had tried to revise and improve the manuscript in line with the suggestions made by you and other reviewers.

According to your suggestion, we make changes to corresponding part of manuscript, details as follows:

 

1. I do not agree with several statements about limitations and advantages of the SSIS deterministic approach. For example, the Authors stated that “SSIS method only takes into account the cumulated drainage area and the slope factors in to calculations, and neglect the influence of real terrain to debris flow, making incomplete and inappropriate results with respect to the actual situation”. Indeed, a correct and accurate definition of the spatial distribution of soil parameters (i.e. cohesion, internal friction angle, hydraulic conductivity) should allow to fully characterize the slope stability index. Of course, this purpose is hard to achieve but in an ideal situation a well-constrained deterministic model should be able to describe the stability factor of a study area. In other words, I think that the low ability of a deterministic model of landslide susceptibility is simply due to the difficulty/inability to define the accurate values of soil parameters. This issue and the usefulness of the introduction of heuristic/probabilistic models to improve the prediction ability of the SSIS method should be better explained in the discussion section.

 

Thanks for your suggestions!

According to your comment, we have revised the statements about limitations and advantages of the SSIS deterministic approach.

 

In line 94-99: given that the actual terrain is extremely complex, cause the physico-mechanical properties varied strongly in spatial. So, it is difficult to obtain the accurate physico-mechanical properties data at medium/large scale. Only the precision of slope factor (obtain from the high-precision digital elevation model) is qualified at regional scale. But it is impossible to replace and reflect the influence of the actual terrain (i.e., steep and confined pathways) to debris flow hazard only depends on slope gradient.

Line 327-334: However, owing to the spatial variability of physico-mechanical parameters, it is hard to obtain the values of these parameters. But, because the cumulated drainage area and the slope factors were obtained from the high-precision DEM, so only these data could precisely enough for indicate the influence of real terrain conditions on debris flow. In this study, the remaining physico-mechanical parameters were assigned based on the land coverage and geological map. Thus, the precision of remaining parameters was not enough for indicate the influence of real terrain conditions on debris flow, making incomplete and inappropriate results with respect to the actual situation.

Line 442-445: owing to the accessibility of high-precision data, it can fix the disadvantage of SSIS method in obtaining accurate and reliable physico-mechanical parameters. And the parameters like LSI, TWI and TRI can reflect the interconnection of pixels. Thus, one of the great advantages was that this model can effectively determine the regions with the terrain condition suitable for the occurrence of debris flow under the support of sufficient disaster inventory and geo-information data.

You can see this modification at the file titled “Manuscript_revised”.

 

2. The Authors can also include the following references about the relationships between landslide occurrence, susceptibility assessment and lithological/topographical factors: a) Lazzari & Gioia (2016) - Regional-scale landslide inventory, central-western sector of the Basilicata region (Southern Apennines, Italy). Journal of Maps 12, 852-859; b) Lazzari, et al. (2018) - Landslide inventory of the Basilicata region (Southern Italy). Journal of Maps 14, 348-356.

 

Thanks for your suggestions!

According to your comment, we have cited these paper to manuscript.

 

Line 77 and line 609-610:

Lazzari, M.; Gioia, D. Regional-scale landslide inventory, central-western sector of the Basilicata region (Southern Apennines, Italy). J. Maps. 2015, 12, 852-9.

 

Line 183 and line 638-639:

Lazzari, M.; Gioia, D.; Anzidei, B. Landslide inventory of the Basilicata region (Southern Italy). J. Maps. 2018, 14, 348-56.

 

You can see this modification at the file titled “Manuscript_revised”.

 

3. Page 1 Line 41: please change “popular” with “urbanized”.

 

Thanks for your suggestions!

According to your comment, we have revised this sentence, because in previous version, it did not state very clearly the meaning.

 

Line 41-42: In this case, relevant studies in these popular research areas have been the focus of many researchers.

 

You can see this modification at the file titled “Manuscript_revised”.

 

4. Page 1 Line 42: Please change “characteristics and reasons for” with “predisposing and triggering factors of”.

 

Thanks for your suggestions!

According to your comment, we have revised this sentence.

 

Line 42-43: However, owing to the predisposing and triggering factors of this natural phenomenon,

You can see this modification at the file titled “Manuscript_revised”.

 

5. Page 2 Line 44: Please add “spatial and temporal” after the word “its”.

 

Thanks for your suggestions!

According to your comment, we have added these words into the sentence.

 

Line 43-45: the total control of debris flow events is always difficult, transforming the focus of contemporary studies from reducing the occurrence of debris flow to predicting its spatial and temporal occurrence.

 

You can see this modification at the file titled “Manuscript_revised”.

 

6. Page 2 Lines 105-108: not clear. Please modify the sentence.

 

Thanks for your suggestions!

According to your comment, we have revised this sentence.

 

Line 106-112: Although, either the deterministic or heuristic/probabilistic models are all appropriate for medium or large-scale debris flow susceptibility assessment [16]. But the deterministic models are difficult to obtain the intensive and reliable field survey data and heuristic/probabilistic models are lack of consideration for initiation mechanism and physico-mechanical properties, so then all hard to get the best results. Thus, determining the optimum model for debris flow susceptibility assessment remains a difficult task.

 

You can see this modification at the file titled “Manuscript_revised”.

 

7. Page 9 Line 223: Please delete “and” after the word “method”.

 

Thanks for your suggestions!

According to your comment, we have deleted this word from sentence.

 

Line 153: Steady-State Infinite Slope (SSIS) method, proposed Random Forest based Steady-State Infinite Slope method (RF-SSIS).

 

You can see this modification at the file titled “Manuscript_revised”.

 

8. Page 9 Line 228: What is the meaning of “source material map”?

 

Thanks for your suggestions!

According to your comment, we have revised this sentence.

 

Line 162-163: source material thickness (thickness of the loose sediments) map and geological map.

 

You can see this modification at the file titled “Manuscript_revised”.

 

9. Page 9 Line 236: Please change “model” with “models”.

 

Thanks for your suggestions!

According to your comment, we have revised this word.

 

Line 170-171: Finally, calculate the prediction accuracy of three models and find out the most optimum model.

 

You can see this modification at the file titled “Manuscript_revised”.

 

10. Page 13 Line 351: Please correct “Pperating”.

 

Thanks for your suggestions!

According to your comment, we have revised this word.

 

Line 364: Receiver Operating Characteristic Curve

 

You can see this modification at the file titled “Manuscript_revised”.

 

11. Page 13 Line 372: Please change “gully” with “gullies”.

 

Thanks for your suggestions!

According to your comment, we have revised this word.

 

Line 385: mainly distributed around the major gullies.

 

You can see this modification at the file titled “Manuscript_revised”.

 

12. Page 18 Line 504: Please change “an” with “a”.

 

Thanks for your suggestions!

This sentence has been removed.

You can see this at the file titled “Manuscript_revised”.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The article shows a very interesting study concerning the analysis of debris flow susceptibility. The article is interesting and innovative, especially from a methodological point of view, by combining two different susceptibility methodologies in order to create one that minimizes errors and shows the greatest possible reliability.

I really appreciated the efforts and revisions made by the authors compared to the first version of the article, and this has led to a significant improvement of the same. The English language also appears to be much improved and the benefits of the revision carried out are noted.

However, some minor aspects remain to be resolved, and I attach my further comments and revisions in the attached pdf.

Good job.

 

Comments for author File: Comments.pdf

Author Response

No.: Water-858502

 

Title: Debris Flow Susceptibility Assessment Using the Integrated Random Forest based Steady-State Infinite Slope Method: A Case Study in Changbai Mountain, China

 

Journal: Water

 

 

Dear Editor and Reviewers:

Thank you very much for your valuable suggestions and comments on my manuscript.

Your suggestions and comments are of great assistance for improving and revising our manuscript, to make it acceptable for publication in Water.

 

I have tried to revise and improve the manuscript in line with the suggestions made by you and other reviewers.

 

Detailed corrections are listed below point by point.

 

Responses to Reviewer 2’s Comments

 

 

Some minor aspects remain to be resolved, and I attach my further comments and revisions in the attached pdf.

 

Thanks for your valuable comments on our paper. Your comments are of great assistance to us for improving and revising our manuscript so as to be acceptable for publication in Water. We had tried to revise and improve the manuscript in line with the suggestions made by you and other reviewers.

According to your suggestion, we make changes to corresponding part of manuscript, details as follows:

 

1. The reference to the study area is missing.

 

Thanks for your suggestions!

According to your comment, we have revised this sentence.

 

In line 21-23: In this manner, a Random-Forest-based Steady-State Infinite Slope method was used to conduct susceptibility assessment of debris-flow at Changbai mountain area.

 

You can see this modification at the file titled “Manuscript_revised”.

 

2. Please cite: 1. Calista, M.; Menna, V.; Mancinelli, V.; Sciarra, N.; Miccadei, E. Rockfall and debris flow hazard assessment in the SW escarpment of montagna del morrone ridge (Abruzzo, Central Italy). Water (Switzerland) 2020, 12, 1206. doi: 10.3390/W12041206

 

Thanks for your suggestions!

According to your comment, we have cited this paper in manuscript.

 

Line 53 and line 564: Monia, C.; Valeria, M.; Vania, M.; Nicola, S.; Enrico, M. Rockfall and Debris Flow Hazard Assessment in the SW Escarpment of Montagna del Morrone Ridge (Abruzzo, Central Italy). Water-Sui. 2020, 12, 1206.

 

 

You can see this modification at the file titled “Manuscript_revised”.

 

3. Following the type of paper, this will be "Figure 1". Check it in the whole text

 

Thanks for your suggestions!

According to your comment, we have revised this through the whole manuscript.

 

For example: line 134 (Figure. 1), and line 147 (Figure. 1 and Figure. 3(a)) and line 155 (shown in Figure. 2.).

 

You can see this modification at the file titled “Manuscript_revised”.

 

4. area ranged from 1755 m to 2655 m a.s.l.

 

Thanks for your suggestions!

According to your comment, we have revised this through the whole manuscript.

 

Line 137-138: The elevations of the study area ranged from 1755 m to 2655 m a.s.l., with a mean value of 2170 m a.s.l.,

 

You can see this modification at the file titled “Manuscript_revised”.

 

5. Is it possible to insert some references to support this sentence?

 

Thanks for your suggestions!

According to your comment, we have added reference in this sentence.

 

Line 139-140: Owing to the occurrence of several eruptions in the past 5000 years [37],

 

You can see this modification at the file titled “Manuscript_revised”.

 

6. No capital letter

 

Thanks for your suggestions!

According to your comment, we have revised this word.

 

Line 206: cohesion

 

You can see this modification at the file titled “Manuscript_revised”.

 

7. 0.89 m

 

Thanks for your suggestions!

According to your comment, we have added space in front of m.

 

Line 232: with a 0.89 m

 

You can see this modification at the file titled “Manuscript_revised”.

 

8. Could you add the hillshade of the area as background and add some trasparency to the land coverage classes and Hydraulic conductivity map?

 

Thanks for your suggestions!

According to your comment, we have added the hillshade of the area as background and add some trasparency to the land coverage classes and Hydraulic conductivity map.

 

Line 235:

Line 240:

You can see this modification at the file titled “Manuscript_revised”.

 

9. apex

 

Thanks for your suggestions!

According to your comment, we have revised this problem.

 

Line 244: ^d Wenfei

 

You can see this modification at the file titled “Manuscript_revised”.

 

10. I suggest to move this part at the beginning of the chapter Material and Methods (line 149) and then add the other parts. Lines from 222-236 are of vital importance to introduce and understand the methodology applied. So modify the text at line 226: it is necessary to cite all the nine terrain and all the ten physical-mechanical parameters applied. Also replace the images in the right order.

 

Thanks for your suggestions!

According to your comment, we have moved this part at the line 152, and cited all parameters. Also, the order of images has been replaced.

 

Line 152: This research conduct debris flow susceptibility assessment using Random Forest (RF) mode, Steady-State Infinite Slope (SSIS) method, proposed Random Forest based Steady-State Infinite Slope method (RF-SSIS), and verify the accuracy of results respectively. Through comparing to find out the most optimum model. The framework of whole study is shown in Figure. 2.

 

Line : 156-162: First, through the topographic map obtain nine terrain parameters (i.e., slope, elevation, curvature, plane-curvature, profile-curvature, topographic wetness index (TWI), terrain ruggedness index (TRI), slope gradient, slope length index (SLI), and distance to rivers) which will used in RF model. The ten physico-mechanical parameters (i.e., cohesion, internal friction angle, hydraulic conductivity, slope gradient, thickness of the loose sediments, cumulative drainage area, length of cumulative drainage, specific weight of water, specific weight of saturated loose sediments and net rainfall).

 

You can see this modification at the file titled “Manuscript_revised”.

 

11. Replace with 'is able to estimate'

 

Thanks for your suggestions!

According to your comment, we have replaced this word.

 

Line 278: As a traditional approach, SSIS method is able to estimate the factor of safety value to measure the slope stability.

 

You can see this modification at the file titled “Manuscript_revised”.

 

12. Replace with 'According to the conservation of mass and Darcy's laws, for a given cell of region with a cumulative drainage area 'a' and length 'b', the steady-state condition can be expressed as ''

 

Thanks for your suggestions!

According to your comment, we have revised this sentence.

 

Line 279-280: According to the conservation of mass and Darcy‘s law, for a given cell of region with a cumulative drainage area  and length , the steady-state condition can be expressed as

 

You can see this modification at the file titled “Manuscript_revised”.

 

13. Please replace the figure with the text

 

Thanks for your suggestions!

According to your comment, we have replaced the figure with the text through whole manuscript.

 

For example: line 281, line 282 and line 283.

 

You can see this modification at the file titled “Manuscript_revised”.

 

14. For the first time, in this figure, the scale bar appears while in all the previous ones only the scale appears as text (for example 1: 4,500). Also add the scale bar in all other images or remove the scale bar from here

 

Thanks for your suggestions!

According to your comment, we have removed all scale bars through whole manuscript.

 

Line 391:

Line 413:

You can see this modification at the file titled “Manuscript_revised”.

 

15. Is it possible to make these tabels bigger in order to make them more visible?

 

Thanks for your suggestions!

According to your comment, we have solved this problem.

 

Line 417:

You can see this modification at the file titled “Manuscript_revised”.

 

 

16. I suggest to start with 'This paper is aimed to analyze debris flow susceptibility of..., located in..., where debris flows, extreme rainfall events and eruptions are widely present.' Please modify this part.

 

Thanks for your suggestions!

According to your comment, this part has been re-written.

 

Line 515-525: This study aims to use the proposed Random-Forest-based Steady-State Infinite Slope method to analyze debris flow susceptibility of Changbai mountain area. The Changbai mountain is located in the east of Jilin Province, where the debris flow disasters caused by the extreme rainfall events were widely present. Meanwhile, as a most famous active volcano in China, if there is an eruption in the future, it may cause collapse or flood events, which will trigger the debris flow disasters. So, it is crucial to assess the debris flow susceptibility of this area, for disaster prevention and mitigation. The RF-SSIS method integrate the Random Forest model with Steady-State Infinite Slope method, using the advantage of RF model (i.e., sensitive to the regions where the terrain conditions are prone to debris flow) and the advantage of SSIS method (i.e., measure the slope stability through the aspects of physico-mechanical properties and initiation mechanism) to further refine the assessment result.

 

You can see this modification at the file titled “Manuscript_revised”.

 

17. Briefly summarize the applied methodology and then describe the main results and conclusions.

Thanks for your suggestions!

According to your comment, this part has been re-written.

 

Line 525-527: The prediction accuracy of RF-SSIS method reached 90.88%, and improving the prediction accuracy by approximately 2.4% and 30.43%, compared with the RF model and SSIS method, respectively.

 

You can see this modification at the file titled “Manuscript_revised”.

 

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

The manuscript introduces an attempt to integrate two well-known landslide susceptibility assessment methods (i.e. the Random-Forest and the Steady State Infinite Slope ones) to improve their prediction ability of debris-flow occurrence in a volcanic landscape of the Jilin Province, China. The manuscript is not well written and it is full of unreadable sentences. Style and grammar of the paper are really inadequate and this strongly influences the comprehension of aims and results by the readers. As a matter of fact, I would like to emphasize the following parts of the manuscript, which, in my opinion, are not easily comprehensible (Pag.1 Lines 17-23; Pag. 2 Lines 62-64; Pag. 6 Lines 183-196; Pag. 6 Lines 191-193; Pag. 8 Lines 219-221; Pag. 9 Lines 241-244; Pag. 14 Lines 375-377; among others). In addition, several concepts and definitions are inexact or too vague (for example, the definition of debris flow (Lines 88-89) or the inappropriate description of the SSIS, Lines 299-303). Again, the first paragraph of the introduction section includes about 40 citations. Although I think that there is a value in the rationale of the paper, the content and structure of the current version of the manuscript is totally inadequate and should be completely re-visited. Thus, I suggest the rejection of the manuscript with an encouragement to the Authors to submit an improved version of the manuscript.

Reviewer 2 Report

The article shows a very interesting study concerning the analysis of debris flow susceptibility. The article is interesting and innovative, especially from a methodological point of view, by combining two different susceptibility methodologies in order to create one that minimizes errors and shows the greatest possible reliability.

However, there are several shortcomings and points left unresolved, especially from the methodological point of view, which make the article not completely understandable. There is also confusion between Model 1 and Model 2.

In addition, the structure and the layout of the article must also be significantly revised and improved.

Finally, I recommend rereading the article by an English reviewer, or in any case I recommend making short, concise and direct sentences to the point, in order to improve the readability of the article.

In the attached pdf, you can find detailed comments.

Comments for author File: Comments.pdf