Influence of Prevailing Wind Direction on Sapping Quantity of Rammed Earth Great Wall of the Ming Dynasty

Round 1

Reviewer 1 Report

Originality / Novelty

The proposed paper novelty is highlighted by the calculation procedure developed by the authors to calculate and analyze the sapping quantity of the Great Wall of Ming Dynasty from China.

Significance of Content

 The proposed research is significant to a wide variety of domain that integrate aspects regarding Earthen structure, structure conservation as well as immovable cultural heritage monuments. The Great Wall of China has been a UNESCO World Heritage Site since 1987 and it is one of the most popular attractions in China that attracts a vast number of tourists. The scale of the construction is impressive as is stretches on 22.000 km and integrates a vast number of watchtowers and fortresses. The wall is made out from a variety of materials, including stone, brick, wood but the most predominant material is represented by rammed earth. The authors have proposed a calculation procedure method that can be used to calculate and analyse the sapping quantity on various sections of the wall.

Quality of Presentation

The paper follows the standard structure of a research paper, it is well organized and integrates a good amount of related works. Most of the related works present various conservation studies, laboratory experiments, statistical characteristics and other analyses focused on the Ming Great Wall or other earthen structures that integrate rammed earth as the predominant material. The paper has a short introduction that provides a great state of the art study of the wind erosion and the development of the sapping quantity paired with the meteorological data sets regarding the wind speed and angle in various regions along the Great Wall.

The following section presents the study area – the Datong County located at the transition zone of the Tibetan Plateau and the Loess Plateau and to the south of Qilian Mountain. This section is far from the ocean and is characterized by continental climate. The authors have analyzed various aspects such as the monthly and annual wind speed means, the number of gale windy days per year as well as the wind rose diagram based on data between 1961 and 2013 obtained from the Qinghai Meteorological Bureau.

The following section entitled methods, provide the steps associated with the proposed calculation procedure of sapping quantity of the earthen structure of the Great Wall. This section is well detailed and represents the novelty aspects of the proposed research paper.

The results and discussion section is divided into two sections. The first section is focused on the Wind Erosion Model proposed by the authors based on their findings. The second section is focused on the relationship between Sapping Quantity and Wind speed, duration, and this is as well based on the research findings associated to the proposed work. The research work shows the variation of sapping volume with all azimuth range at both sides of the Great Wall. Figure 8 presents the Sapping quantity at both Leeward and Windward directions.

The conclusions section is derived from the results of the proposed analysis. Rammed-earth structures are affected by several environmental factors out of which the most important are wind, light, heat and water. As presented by the authors, multi-disciplinary work is required to predict and reduce the deterioration of the Great Wall and other rammed-earth relics.

Scientific Soundness

The proposed research analyzing method is useful to provide reference for the deterioration of rammed-earth structures related to the influence of long-term wind pressure.

Interest to the readers

The proposed work has a high interest for readers and scientists that are focused on the preservation of cultural heritage immovable monuments. Some of the most impressive immovable monuments integrate rammed-earth as the main material, therefore the proposed research has a high interest to prevent deterioration associated with wind pressure and the influence of sapping quantity of these earthen structures.

Overall Merit

The proposed paper provides a great analysis of the influence of wind pressure on sapping quantity of earthen structure. The study offers theoretical support regarding the reinforcement of earthen structure relics to support conservation works in the future.

Other concerns:

The paper requires minor corrections as some aspects of the template have not been removed from the proposed paper.

The methods section integrates a section from the Coating journal template between line 96 and line 98.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Authors performed research focused on sapping caused by wind erosion causing deterioration of earthen structure.

Good introduction, supported by adequate and recent references. Aims clearly stated.

On Study Area, explanation is clear but authors must refer origin of presented data, for instance on line 68 to 77.

Methodological approach is adequate and correct, but more supporting references and/or Norms and/or Protocols are needed!

Results presentation is, in general, clear and sound.

Discussion is poor, must be improved comparing obtained results with similar ones on adequate references; chapter Results and Discussion is actually a detailed technical report.

Conclusions are coherent with obtained results but can be strengthened after improving discussion as suggested.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

I was asked to read and comment your manuscript entitled “Influence of Wind Pressure Development on Sapping Quantity of Earthen Structure”, you proposed for publication by Coatings.

The research considered a case study, with the aim to relate erosion of earthen structures to wind action, by reference of historical wind parameters. I agree this aspect could insert well in the knowledge framework often focused on other climatic and human factors. I also agree, it could offer theoretical bases for interventions of protection, restoration and preservation of cultural heritage.

Nonetheless, I confess it is not easy for me to evaluate the manuscript: unfortunately, I cannot consider it  positively in this phase.

In my opinion, state of the art, theoretical bases, methods, results and discussions are often proposed together, and there is a discrepancy between proposed formulas, collected data and interpretation of results (e.g., formulas introduced but not applied to the case study, too general and not very thorough considerations, conclusions barely mentioned but not fully supported by the data). Much of what proposed, already from the title, is no or little proven (or even discussed) in the text. I think the paper needs to be rethought and largely modified/improved, before it could be considered for publication.

So, I proposed the editors to reject it, already in this phase. 

Research starts from a specific and potentially interesting problem, but in reader’s mind several unsolved questions arise from the way in which it is proposed.

You may find my line by line comments in the text (see the attached file). Below, I summarized some critical points and suggestions.

- I am not a native English, so I am not the most suitable in proposing any linguistic and stylistic review. Nonetheless, I found the text quite plain and clear, and probably only minor linguistic adjustments are needed. Apart from that, methods, results and discussion are often mixed throughout the text (e.g., lines 99-101, 111-112, 146-148), or randomly proposed (e.g., lines 85-94), with a style that could be better indicated in a thesis but is not suitable for a scientific article. Thus, the text looks a quite confused and a reorganization is needed.

- From what I can see (e.g., following the diagram in Figure 5), there was an important work in collecting data, and in the field as well, but it looks penalized by some concrete choices in returning data. For example, photos, drawings, mapping of archeological remains, or schemes where probably collected in the first phases: why not to include some example? Why not to insert drawings, diagrams or detailed photos instead of panoramas (e.g., Figure 6a, 6c)? There are several methods commonly used in Archeometry and Geoarcheology, and I think in Engineering as well.   

- Research aims to quantify  the development of wind erosion after a long period (e.g., line 49-50): to achieve this goal, photographs, schemes, reports covering at least the interval 1961-present should be considered. Why not to compare the present situation with historical images (if available), from which one can follow the evolution of the deterioration of the structures over time? I may suppose this have been done, but no evidence is provided to the reader. Otherwise, effects of erosion may cover the whole 1572-present interval.

- You have identified wind erosion as the main cause of the deterioration of rammed earth structures, and this is feasible: anyway, how could you prove erosion is only wind-caused? Actually, you cited other phenomena (cryoclastism, thermoclastism, human impact among other): why did you exclude them in this study? Are they (or are they not) distinguishable from effects of wind erosion? I think more details are needed, only if to cite and discuss previous researches.

- Starting from the title, you talk of wind pressure.  If you refer to the force exerted by wind on the study structures, this is not discussed in the text. You mainly discussed the relation between effects of wind erosion and the orientation of walls respect to the main wind direction. Again, you divided the orientation of walls in steps of 5°, for an easier analysis of data. Does each 5° interval contain the same number of segments? That is, total length (and consequently comparable surfaces) is the same for all the considered azimuths? Otherwise, the sapping effect could reflect also on the differences in total exposed surfaces for each direction. Probably, to refer to a standard reference surface rather than (or not only) to cumulative areas could be preferable... 

- Move all the theoretical aspects to methods or introduction sections, or to a dedicate sub-section. Anyway, please consider theoretical aspects are only a stylistic exercise and  totally useless if not applied to the case study. Several assumptions are correct but very general: what about your research? For instance, at line 53 you talk about wind tunnel tests: I think the results are reported by quoted papers [11-14] but implication to the present research are not discussed. A brief comparison between theoretical and experimental data, and the results of this study would help improving the research. In fact, to propose only formulas (such in section 4.1) is useless. Again (lines 146-148, section 4,2): what is the relation with sapping quantity? Results are not discussed... Lines 182-188: instead of general considerations, please explain how does it apply to the case study. In the end,  the only result you clearly propose is the relation (quite obvious, anyway) between the azimuth of walls and the wind direction, according to Figure 8. But please note how, still in this figure, peaks 19-31 on both leeward and windward sides need an explanation, but they are not discussed. In the same way, potential for preservation of cultural heritage is just mentioned at the beginning and the end of the manuscript, but not really remarked.

My final opinion is this research has a potential, although it represents a single case study, but needs to be valorized through a better organization of the manuscript, an improved presentation of methods and collected data, a deeper discussion of results in the light of theoretical bases and former papers. After you fixed these aspects, I believe that the work can be submitted again and considered more favorably for publication.

I hope my comments, with which you may of course agree or not, could be of some help in this phase.

Best regards

The Reviewer

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Discussion still very poor, must be much more improved!

Author Response

Dear Reviewer,
Thanks for your useful comment to the revised manuscript.
According to your comment, related discussion about wind erosion, wind direction and erosion, windward and leeward side and conservation measures are added in the manuscript and compared with results and conclusions of relevant research. At present, laboratory test and numerical modelling are dominated methods in effect evaluation of wind direction on buildings. For ancient earthen sites more than 400 years old, relatively few research about effect of wind direction on erosion could be found. This manuscript uses field investigation as method to assess effect of wind direction. In the subsequent research, we would adopt numerical modelling as supplemental method.
Thanks again.
Best regards,
The authors

Reviewer 3 Report

Dear Authors,

I read the revised version of the manuscript, and I find it was reconsidered and reorganized, also properly taking into account my suggestions. I really appreciated it, thanks.

The text has been improved, and the unclear points better explained. Figures have been improved as well, although they still look of low quality in the .pdf file. Check them in the final editing. 

I only found minor points, which I highlighted in the attached file, you should consider before publication.    

Thus, I think the paper could be accepted after (very) minor revisions.

Kind Regards

The reviewer

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thanks for your helpful suggestions and positive comments to the revised manuscript. It is your meticulous work that help us to improve the manuscript.

According to your comments, we recheck the figures and revise the manuscript point to point.

Thanks again for your hard work.

Best regards,

The authors