Temporary Confined Water-Induced Landslide in the Binary Structure of a Gentle Slope: A Case Study of the Fanshantou Landslide
Round 1
Reviewer 1 Report
I regret to say that, in my opinion, the manuscript "Mechanism of Landslide Induced by Transient Confined Water in a Binary-Structure-of-Permeability Accumulation—the Case of Fanshantou Landslide" cannot be considered for publication on Water.
I'm listing below the main reasons for that. Other observations, that I hope will be useful to the Authors to go on with their interesting study, are provided as annotations in the attached pfg.
- The introduction section is very confused and does not sufficiently explain the general interest of the case study, what the Authors mean from a physical point of view by "transient confined water", which landslide typologies are affected by the hypothesized triggering effects, how the international literature has progressed on this topic.
- The geological description of the study area is not sufficiently developed.: there is no geological map, the geological section shows only very basic information, figs. 2-4 are not of good quality and there is no correspondence between them and several sentences of the text in section 2.1.
- The subsoil characterization is not sufficiently illustrated. Some data are given without mentioning the type of test used to determine it, the location, the number of samples, etc.
- Permeability tests are mentioned but their results are not plotted. The permeabilities values inferred from these tests are just mentioned. No comment is given about the limited number of tests and, therefore, the uncertainty in extending their results to the whole formation.
- Total heads were measured directly in the boreholes instead than in piezometers. The physical meaning of such measure and the correspondence with pore water pressures acting in this layered subsoil is rather questionable
- The correlation of water levels with rainfall, based on experimental evidence, is only qualitatively described by fig. 5, the monitoring period is very short and does not seem to allow to draw general conclusions.
- The correlation of landslide events with rainfall is discussed in an excessively qualitative way
- The numerical simulations are not particularly original, do not seem to add much information to the understanding of the investigated category of landslide phenomena, and most of all the choice of parameters is not sufficiently discussed or validated by experimental evidence.
- No parametric calculation is carried out, limited discussion about the reliability of the assumed parameters is provided.
- The time of simulation and comparison with measurements appears excessively short.
- water pressure increase is considered the triggering factor of the landslide, although stability calculations are completely missing in the study.
- In discussion and conclusion sections, the original contribution to the research topic provided by this work is not sufficiently highlighted. It is also not very clear which is the "type of landslides" (mentioned several times in the manuscript) to which the Authors assume that the study case belongs. Therefore, the general outcomes of this study, and the possibility to extend them to other cases, do not clearly derive from the results or their discussion.
Comments for author File: 
Comments.pdf
Author Response
We are very grateful to your detailed and nice comments for the manuscript. Your suggestions are valuable to improve this manuscript. Please note that the modifications made in the text are marked in red in the revised manuscript. Our responses to your comments are listed below. Thanks a lot.
Please see PDF as below！Best Wishes！
Author Response File: Author Response.pdf
Reviewer 2 Report
This paper discussed the landslide mechanism in a Fanshantou slope with transient confined water in a binary-structure-of permeability. The idea is interesting. The following comments may help the authors improve their draft to better understand by the readers:
- The title seems strange in English. Find a native speaker to clarify the title.
- P. 2, Line 48, “Such landslides are developed widely in subtropical area”, references are required to support the statements.
- P. 2, Line 52, “It should be noted that although a large number of …water in accumulation landslides”, references are required to prove the statements. The following references may fit the statement of the rainfall-induced landslides and need to be cited.
(1) Establishing the Rainfall-Based Warning System for Slope Failure in Alishan Highway (doi:10.6652/JoCICHE.201911_31(7).0005)
(2) Investigating the Rainfall-Induced Groundwater Variation and Movement of Highway Slope, Disaster Advances, Vol. 6(12), pp. 142-153
(3) Slope Management Criteria for Alishan Highway based on Database of Heavy Rainfall-induced Slope Failures, Engineering Geology, Vol. 162, pp. 97-107
(4) Post-failure simulations of a large slope failure using 3DEC: The Hsien-du-shan slope, Engineering Geology, Vol. 242, pp. 92-107
- P. 2, Line 57, “The permeability of the surface soil…less than that of the deep soil layer”, add the values of the permeability in the slope.
- P. 2, Line 67, “using simulation” should be changed to “using numerical simulation”.
- Fig. 2, the north index and scale are not clear.
- Line 82, “cracks appeared in the floors of 13 houses in…”, clarified the location or elevations of the 13 houses. The cracks are considered as precursors in the large landslides and should be mentioned clearly.
- Line 83, “arc-shape crack formed from west to east”, the cracks are located at the toe of the landslide, crown of the landslide or the crown of the slope? Clarify the locations.
- Line 99, “water level rises sharply, and the water is turbulent…water flow is low and the water depth is 0.2-0.5 m”, why the water is turbulent? In addition, the water depth is in which location?
- Line 109, “when h, the average cumulative rainfall can reach…”, check to English.
- Line 113, “The Yuyan stream flow”, add the Yuyuan stream to Fig. 2.
- Line 116, “There exists a gully on the southeast side of the landslide”, specify the gulley in Fig. 2.
- Clarify the time to get the topographic data for Fig. 3 in the draft.
- Line 156, “This rock mass is relatively intact”, provide the quantitative description of the intact rock, such as RQD.
- Line 160, “As stated above”, clarify the “above” mentioned here.
- Line 162, “Pumping tests were carried out in boreholes…are 2.85E-8 m/s and 5.61E-10 m/s, respectively”, additional statements are required to clarify the pumping tests. Are holes drilled along the whole pipe or part of the pipe? In addition, if there are more than one rock mass in a borehole, did packing conduct to separate the rock mass to get permeability of individual rock mass?
- Line 176, “Controlled by the hydrological structure…higher permeability”, a figure should be added to show the relationship mentioned in the sentence.
- Line 268, “Profile 1-1’ is selected as the …” should be changed to “Profile 1-1’ in Fig. 3 is selected as the …”.
- Line 271, “by Geo-studio software”, should it be changed to “by Seep/w in Geo-studio software”? Which version is used in the study?
- Line 278, “According to the engineering experience…”, references must be added to clarify the experience.
- Fig. 12, the authors must clarify what kinds of rainfall data (hourly rainfall, daily rainfall or monthly rainfall) were used to the input? In addition, the boundary conditions are not clear in the paper.
- Line 333, “The measured rainfall data” should it be changed to “The measured daily rainfall data”?
- Line 357, “As analyzed above” specifies the “above” in the paper.
- Line 366, “in Fig. 19”, it seems no Fig. 19 in the paper.
- Line 371, “Therefore, the key to control the landslide…from the rear edge of the slope”, numerical simulations must be conducted to verify the statements.
- Line 384, “rainfall (<100 mm), moderate rainfall (100-250 mm)…10mm/d, 20 mm/d, and 30 mm/d”, it is not clear how the authors can transfer the rainfall to the rainfall intensity used in the study.
- Figs. 16, 17, and 18, the curves are hardly distinct in black and white print.
- In this study, only the continuous rainfall pattern was discussed. How about the impact of different rainfall patterns? In addition, why the authors only discussed the groundwater movement but not the slope stability? The authors must conduct the slope stability analysis to tell the readers that the slope may fail during the heavy rainfall especially after considering the binary-structure-of permeability accumulations.
- Find a native speaker to sharp the English of the draft.
Author Response
We are very grateful to your detailed and nice comments for the manuscript. Your suggestions are valuable to improve this manuscript. Please note that the modifications made in the text are marked in red in the revised manuscript. Our responses to your comments are listed below. Thanks a lot.
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I regret to say that, even if the Authors kindly replied to all my observation in the "Response to Reviewer 1 Comments" coverletter, they aimed more at justifying their previous choices than at really improving their manuscript. Unfortunately, I feel that most of the problems of the previous manuscript are still present in the new version. I have no other possibility than suggesting again that this work cannot be considered for publication on Water.
1. In the new introduction, the importance of confined water is mentioned many times but the reason why it should be treated differently from any other effect of pore water pressures on stability is still obscure. There is still almost no indication of the landslide typologies and involved materials on which the referenced literature studies are focused.
2. There is still no geological map and the geological section has not been improved
3. Despite the Author's explanations, I'm still convinced that one month of simulation is insufficient to draw any general conclusion
4. The location and number of tests was not provided, justifying this choice by replying that "if a lot of tests are introduced in the text, it will cause the text to be messy.". Explaining, even by a figure or a table, where the tests were carried out and how many tests were carried out for each typology, would have been a way to prove the reliability of the parameters used for simulations.
5. The choice of parameters is still not sufficiently discussed or validated by experimental evidence. No new parametric calculation was carried out, limited discussion about the reliability of the assumed parameters was provided. The Authors replied on the previous observations on this point by mentioning the different precipitations parametrically considered. This was not the actual problem. Permeability, characteristic curves, and also cohesion and friction angle in this new version, are either only asserted or not sufficiently justified from experimental evidence. This makes the results of numerical simulations questionable and the possibility to generalize their results quite limited.
Author Response
Dear reviewer 1,
We are very grateful to your detailed and nice comments for the manuscript. Your suggestions are valuable to improve this manuscript. Please note that the modifications made in the text are marked in red in the revised manuscript. Our responses to your comments are listed below. Thanks a lot.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors did a good job to improve their draft. Almost all my questions were answered. However, the authors still need to deal with the minor modifications after accepting the draft.
- Check the format of the references. Some references seem not follow the regulation of the draft.
- In the vertical axis of Figs. 12 and 13, the authors used saftey coefficient and Fs. Should they be the same and the correct name be safety factor? Also check the spelling in the text.
Author Response
Dear reviewer 2,
We are very grateful to your detailed and nice comments for the manuscript. Your suggestions are valuable to improve this manuscript. Please note that the modifications made in the text are marked in red in the revised manuscript. Our responses to your comments are listed below. Thanks a lot.
Please see the attachment.
Author Response File: Author Response.pdf
