Multi-Scale Engineering Geological Zonation for Linear Projects in Mountainous Regions: A Case Study of National Highway 318 Chengdu-Shigatse Section

Round 1

Reviewer 1 Report

Well done.

Author Response

Thank you for the affirmation and appreciation of the research content of the manuscript.

Reviewer 2 Report

Dear author,

I recommend the publication of this manuscript but you should complete the references with the owners of the software and their versions.

Best regards

Author Response

Thank you for the affirmation of the research content of the manuscript. Inlight of your suggestion and recommendation, we properly mentioned the specific version of the software as well as its company trademark too in the references. We are looking forward to any other recommendation and comments from you once again.

Reviewer 3 Report

Overall comment

This MS showcases a two-stage susceptibility mapping approach for zoning engineering geological conditions for highway project. It is an interesting study because highway and railway engineering in mountainous region are at high risks of geological hazards, and prior estimation of engineering geological condition will be beneficial for the design of these highways and railways. To do so, the authors present a so-called multi-scale method, wherein two steps are included, i.e., regional zoning using AHP method and key section zoning using LR method. To illustrate the presented method, the 318 Chengdu-Shigatse national highway is used as a case study. Generally, the MS focused on the issue that deserving discussion, and is suitable for a publication in Remote Sensing. However, as I read through the MS, I found some issues that should be better clarified. Please see the specific comment below.

Specific comment

(1)  A major limitation of this MS is that the highlights and innovations are not clear enough. The authors highlight their method as a multi-scale one throughout the MS, however, it seems that it is better to describe as a two-step method that regional highway and key section are considered. Individually, the used method for each scale, i.e., the AHP for regional zoning and the LR for key section, have long been discussed in previous study, the MS doesn’t improve the methods, but only combine these two method methods as a weakly connected approach. In this sense, due to the lack of novelty in methodology, the MS looks more like a guideline for practical work, rather than an original article.

(2)  The structure of the MS should be improved. I thought the MS is focusing on a new multi-scale approach for engineering geological zonation when I read through the abstract. However, the structure of the body text show that it seems more like a case study, as the description on the case are much detailed comparing to the methodologies. I suggest the authors focusing on the novelties and innovations of their approach, which helps highlight the impact of their study.

(3)  Many descriptions in the text are confused. I list some of them for the authors’ consideration. The authors mentioned linear projects in the MS, which includes highway, railway, and pipelines. Is the approach presented in the MS appropriate for all these projects? As the structure of the MS seems like a case study, wherein only highway is used for application, I suggest the authors focusing on highway rather than linear project. Similar problem exists in the following texts. Such as “the method suitable for high-altitude mountainous areas”, is there any special consideration for the factor of altitude? Unfortunately, I failed to find it in the methodology section. The term “high-altitude mountainous areas” may be more appropriate to describe the case of the national way, rather than the method itself.

(4)  Another key word refers to “engineering geological”. It is appropriate for the regional zoning, as it focused on the engineering geological condition. However, for the key sections, the evaluation object turns to landslide susceptibility. Does the engineering geological condition equate to landslide susceptibility?

(5)  Section 3.1. Prior to the methods, the authors choose to describe the used data, and data sources are listed in detailed in the first paragraph. I don’t think it is a good way to introduce the methods. Why these data are used? Are they necessary for regional engineering geological zonation? It may make the readers confused. I suggest the authors add more explanations on why these data are chosen.

(6)  The description on the methodology is weak, but many key information which should be a part of method, are separated to other sections. Such as, Section 4.1.1, the evaluation model and evaluation factors are obviously belonging to section 3.2.1.

(7)  Figure 5, the figure is not drawn in a scientific way, that the titles of coordinates, the units in the color bars, are missed.

(8)  Section 4.2.1. The authors interpret landslides 780 landslides historical samples through Google Earth images. What kind of method is used for interpretation, manual visual solution or computer vision based? Are these obtained landslide samples accurate? I ask this because many objects are often mis-classified as landslides, in particular at mountainous regions. Besides, I wonder whether the landslides are sufficient to support the engineering geological condition? As landslide is one symbol of poor engineering geological condition, other hazards, such as rockfalls, debris flows should be considered.

(9)  In Eq.2, P(T) denotes the time probability index, could the authors add some more information how they evaluate this variable during construction the model.

 

(10)           Panel a in Figure 8. I am confused on the figure legend. The red units and blue units denote the landslide units and non-landslide units, respectively. That is OK, I wonder what do the grey units stand for? Do these slope units contain landslides or not? I believe there must be some editorial error in this panel. 

Improvement on the quality of English Language is suggested.

Author Response

Thank you for your valuable suggestions. We have responded to each comment. Refer to Attachment Response to Reviewer 3.

Author Response File: Author Response.docx

Reviewer 4 Report

Dear Authors,

As far as I am concerned, the manuscript quite marginally falls within the journal objectives, as remote sensing data play a very weak role in the manuscript in its current structure.

The methods section is very poor, while most methods descriptions (which need substantial improvement anyway) are included in the results sections.

The discussion is also poor, as it is substantially lacking any analysis and comparison in respect to the existing international literature.

More detailed comments can be found hereunder.

All the above conditions and following comments are important factors preventing me to accept the manuscript for publication.

I suggest the Authors to perform a deep revision of the manuscript following all the comments in order to obtain a document in line with the current international know-how about the topic.

 

Best regards.

DETAILED COMMENTS

41: tectonic uplift instead of structural?

44: which is the meaning of “favorable hydrological conditions” and how favorable conditions link to geological hazard? Please explain.

45: most active or mostly affected?

50-66: cited literature refers to national scale case studies and methods only, but, in an international perspective, further literature must be added and taken into account. See, as an example only, the International Association for Engineering Geology and the Environment’s Commission guidelines (https://iaeg.info/c25egmguidelines).

78-80: unclear. Check syntax. Moreover, Authors must provide a definition of the concept of “key section” which is introduced here.

Figure 1: add references/info for elevation data and coordinate system.

105: Authors refer to thousand km study area and affirm that “Natural disasters such as collapses, landslides, and mud-104 rock flows are widely developed in the area” with the photos of Figure 2 only. This is a very weak support. They should describe the relevance of this issue in a more robust way along the road.

Figure 2: this figure illustrates slope processes, not hazards. Please check.

110: this sentence and the adjective “complex” refers to a huge area, so it sounds quite meaningless. Do all the tectonic units are “complex”? Which is the meaning of the term? “Complex” for which reason and parameter?

110-119: all this description and toponyms must find correspondence in Figure 3.

Figure 3: this is not really a geological structure map, because it shows faults only, and faults are not classified for their kinematics, activity, etc., and what about folds, tectonic units, etc.? Please improve this figure with all relevant structural geological features.

122-127: very generic description. Is this information useful/necessary for the research development? If true, more detailed information should be provided.

134-135: add source literature for geology.

144: as previously highlighted, Authors must provide a definition of the concept of “key section”, which instead is introduced only later.

144-154: this description of landslides identification criteria and methods is unclear, generic, and based on terms which do not refer to international nomenclature criteria. Moreover also some errors may be found in the text, like “…The color tone of the landslide area is different from that of the surrounding surface objects, and there is no vegetation growing inside it, so it appears white or gray in the image…”. The “colour” may be the same inside and outside the landslide depending on the landslide type. Vegetation either may survive inside the landslide, or may rapidly regrow. “White or gray” depends on the kind of images used (panchromatic, multispectral, false or true color composites, etc….

Please rewrite and refer to the literature. Moreover, this is the data section, but it seems this description refers to methods. Are the Authors acquiring landside data from the literature?

165-166: Authors refer to “preventing geological hazards”. They have to clarify this point to highlight if they really can “mitigate hazard” or eventually they can mitigate risk by acting on vulnerability.

Figure 4: symbols of the figure must be included and described in the caption.

175-195: this part is too generic and lacks any references to the well-developed international literature. Only two papers in Chinese are considered. Moreover, the use of the “crust” term in this context is questionable. Why 30 km? Why four classes? Hence, this section of the paper should be completely rewritten, because almost no methods are described.

189-190: add literature to support this sentence.

199-200: “…The key section is the area with poor engineering geological conditions…”. Poor is not included among the four classes previously introduced. Why? So, how the poor conditions are defined?

202-204: unclear text. Please check. What “evaluation range” does it mean?

206-207: unclear to the reader. Are slope units square pixels? Looking at figures it seems they aren’t. How did the Authors obtain these units? Please, refer to the international literature to introduce this concept and related methods.

211-218: definitions about hazard are unclear and they do not refer to any international paper or literature. Moreover, the Authors, a) are “mixing” in the text geological hazard and landslide hazard (which are not the same), b) do not describe any detail about the methods they intend to develop and apply. What about landslides, their types, state of activity, the inventory, its accuracy?

221-267: these are almost completely methods, so they shouldn’t be located in the results section.

226: the Authors talk about widespread “application” of the method, but few literature is cited, without any consideration/analysis about the implementation approach better fitting with their case study.

234: the Authors briefly refer to the geology of the area, but why don’t they include lithology among the parameters? The international literature highlights that lithology is an important factor in engineering geology behavior. And what about slope steepness? There are no considerations about that, while the Authors should check how stable/unstable is the resulting map when changing the set of parameters.

273-280: same as above. How were the factors defined? Which is the reference literature? Who were the “experts in the field of engineering geology”? Aren’t the Authors “expert”? This is a crucial part of the method, but it is not possible for the reader to verify and/or judge anything.

Figure 5: add coordinate systems to this and the following images.

Figure 6: explain the meaning of codes G, M, SW, W.

308: it seems only landslides are considered, so why are the Authors using the term disaster?

309-312: what about the detailed methods to map landslides? What about the accuracy for this analysis? A very large literature exists about this topic, but the Authors do not include any references to support the methods they chosen.

315-368: these are almost completely methods, so they shouldn’t be located here.

Figure 7: which is the spatial connection of this area with previous figures?

316-318: the Authors talk about geological engineering zoning but they consider “the spatial probability, magnitude probability, and time probability of landslide occurrence” only. So, is their zoning based on landslides only? If this is true, why are they talking about geological engineering, being the latter a wider term including further processes?

323-325: “The geological hazard susceptibility index can replace the spatial probability index of landslide disaster occurrence. Susceptibility refers to the probability of geological hazards controlled by geological conditions in a certain area.” Again, the Authors skip any reference to well-developed literature highlighting differences between hazard and susceptibility. It seems here that they are going to analyze susceptibility, so why did they introduce hazard? Is P(S) “probability index of landslide occurrence” the spatial probability? This part of the text is quite disappointing, moreover it’s located the wrong location.

342-347: No literature is given here, and also no analysis about the effects of training data sampling choices.

348-355: very hard to understand to the reader, no reference literature. No previous attempts found in the literature?

410: in the discussion the results are described as a whole, but no analysis is made about uncertainties of the methods, possible limitations, possible improvements. Moreover, no comparisons are made with previous similar research known from the literature. Within the whole section only one reference is cited! So, which are the lessons learned? Which are steps ahead this research allowed to perform in respect to the literature? Hence the discussion needs substantial improvement and reorganization.

415: they are not “higher precision” zones, as zoning is based on different methods.

English is almost fine, even though some sentences need a check as highlighted in the detailed comments.

Author Response

Thank you for your valuable suggestions. We have responded to each comment. Refer to Attachment Response to Reviewer 4.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

I appreciate the improvement in the revised manuscript. The authors have done good jobs to address most of my initial suggestions adequately. I believe the revisions in the current manuscript makes this a stronger paper. Readers should be better able to access the findings of their study. I suggest a possible publication in Remote Sensing.

Z. Han