Multi-Criterion Analysis of Cyclone Risk along the Coast of Tamil Nadu, India—A Geospatial Approach

Round 1

Reviewer 1 Report

The manuscript entitled “Multi-criterion analysis of Cyclone Risk along the Coast of Tamil Nadu, India - A Geospatial Approach” presents an approach to estimate the coastal hazards and its vulnerability and risk using various physical, socio- economic parameters and the geospatial and AHP techniques were used to execute the model. The manuscript has a good potential, however there is some flaws in the manuscript which needs to be addressed for the possible publications.

The abstract is not informative, there is no quantitative information pertaining to the findings, which should be added in the abstract.

Study area is too lengthy, study area required to rephrase with brief information of the study area, there are unwanted information’s are filled with. The study area map is not up to the standard for a publication, and the quality of the figure is also very low. No Scale, north arrow etc.

It is not clear about the data used in the study mentioned in the table 1 (Data sources of both primary and secondary data), How Coastline is extracted from the NOAA, and which year, similarly the year of the LULC, NDVI is also missing.

The methodology session should be modified as how the variables are categorised with respect to the risk factor, and discuss how it influence in various hazards.

Figures doesn’t have the quality, improve.

The equation used for the risk analysis is need to be discussed, what is the source of the equation? If the equation is developed by the authors, what is the authenticity, and how it is validated.

Discussion and conclusion is well written, however it can be improved with more critical discussion on the findings and models used.

Author Response

  The manuscript entitled “Multi-criterion analysis of Cyclone Risk along the Coast of Tamil Nadu, India - A Geospatial Approach” presents an approach to estimate the coastal hazards and its vulnerability and risk using various physical, socio- economic parameters and the geospatial and AHP techniques were used to execute the model. The manuscript has a good potential, however there is some flaws in the manuscript which needs to be addressed for the possible publications.

The abstract is not informative, there is no quantitative information pertaining to the findings, which should be added in the abstract.

Authors’ response

As suggested by the reviewer, the quantitative information is added in the abstract.

Study area is too lengthy, study area required to rephrase with brief information of the study area, there are unwanted information’s are filled with. The study area map is not up to the standard for a publication, and the quality of the figure is also very low. No Scale, north arrow etc.

Authors’ response

As suggested by the reviewer, the study area is rephrased where some of the important geographical information required to know about the study is retained as the study area tries to explain the general characteristics of the region like location, geomorphology, and its characteristics. Hence the study area is bit lengthy. Authors feel this is important because any disaster affecting will lead to huge economic loss for the state and the country and the maps are updated.

It is not clear about the data used in the study mentioned in the table 1 (Data sources of both primary and secondary data), How Coastline is extracted from the NOAA, and which year, similarly the year of the LULC, NDVI is also missing.

Authors’ response

The database from which the source data obtained and their website is given in the Table 1. Whereas the exact information like how exactly the data is extracted and the year of data considered is given in the methodology section 2.4 in their respective data sections.

The methodology session should be modified as how the variables are categorised with respect to the risk factor, and discuss how it influence in various hazards.

Authors’ response

As suggested by the reviewer, the methodology section is updated in section 2.4.

Figures doesn’t have the quality, improve.

Authors’ response

As suggested by the reviewer, the figure qualities are updated.

The equation used for the risk analysis is need to be discussed, what is the source of the equation? If the equation is developed by the authors, what is the authenticity, and how it is validated.

Authors’ response

As suggested by the reviewer, the authenticity and the development of equation are explained in the manuscript in line no. 556.

Discussion and conclusion is well written, however it can be improved with more critical discussion on the findings and models used.

Authors’ response

As suggested by the reviewer, the discussion and conclusions are improved

Reviewer 2 Report

Please find my comments attached.

Comments for author File: Comments.pdf

Author Response

Comments on “Multi-criterion analysis of Cyclone Risk along the Coast of
Tamil Nadu, India - A Geospatial Approach”

General

The manuscript analyzes tropical cyclone risk at the Tamil Nadu using simplified
approach of GIS and MCDA. The intention seems important for risk management,
however, there are several points I felt that there are insufficient or unnecessary
parts in the manuscript and their method section is unclear. Since I am not
convinced with the current explanation of their method, I put less effort to read
the result and discussion part. I would prefer another round of review once the
current version of the method improves.

Therefore, I would like to ask the authors for revising the manuscript so that their
achievement is clearly shown. The points I would like to ask the authors to revise
are as follows

1. 
   In my impression, the authors’ main target is not clear. It should be clearly
   discussed in the introduction section.

Authors’ response

As suggested by the reviewer, the introduction section is rewritten.

2. 
   The method section contains several theoretical statement rather than
   important detail of their analysis, map preparation and so on. Hazard map
   preparation lacks scientific novelty. The rationale of hazard map and limitation
   should be discussed in a clear manner.

Authors’ response

As suggested by the reviewer, the above comments has been addressed and updated in the methodology section.

3. 
   Graphs, maps are needed to be improved significantly. Authors are requested
   to investigate the state of art of preparing any maps/figures.

Authors’ response

As suggested by the reviewer, the quality of maps are improved.

Individual comments

Abstract
L17: It should be “Tropical cyclone is…”

Authors’ response

As suggested by the reviewer, the statement is corrected.

L25-27: This statement is too general and it is almost certain. Please discuss
major/highlighted results from your risk assessment.

Authors’ response

As suggested by the reviewer, the results are discussed.

Introduction

L72-74: The risk assessment was…

It lacks references. You may consider to cite following literatures that are from
general to different hazard perspectives

Cardona, O.-D.; van Aalst, M.K.; Birkmann, J.; Fordham, M.; McGregor, G.; Perez,
R.; Pulwarty, R.S.; Lisa Schipper, E.F.; Tan Sinh, B.; Décamps, H.; et al.
Determinants of Risk: Exposure and Vulnerability; Cambridge University Press:
Cambridge, UK; New York, NY, USA, 2012; pp. 65–108.

Authors’ response

As suggested by the reviewer, the citation has been added.

L80-81: In my impression, comparing Bay of Bengal with the Arabian Sea is not
appropriate since both your studied region and Bay of Bengal are adjacent to
North Indian Ocean. You may check recent statistics of North Indian Ocean
tropical cyclone from recent studies.

Authors’ response

Authors disagree to the reviewer comments. Because the authors tried to discuss this statement because a small strip in the zone 5 falls in the Arabian Sea. So, the intention of this statement is how different part of the region in study is affected by cyclones.

L81-83: Considering your discussion on possible climate change impact on TC
activity in the above paragraph, it may be more ideal to discuss any TC statistics
relevant to current decades, such as 1980-2021 (when the impact of climate
change is likely visible).

Authors’ response

Authors tried to discuss about the cyclones that is occurring around the Indian peninsular and its landfall. The recent decade cyclones are discussed in the section 2.3.

L83-85: Again, updated statistics are more desirable. Please check

Alam Md M, Hossain Md A, Shafee S (2003) Frequency of Bay of Bengal cyclonic
storms and depressions crossing different coastal zones. International Journal of
Climatology 23:1119–1125. https://doi.org/10.1002/joc.927

Authors’ response

As suggested by the reviewer, the citation has been added

Material and methods

Section 2.1: Please keep this section brief as it contains very general aspects of
the studied region.

Authors’ response

Authors modified the section 2.1 by including the segmentation of the study area as shown in Figure 1 as suggested by the other reviewer. The study area tries to explain the general characteristics of the region like location, geomorphology, and its characteristics. Hence the study area is bit general. Authors feel this is important because any disaster affecting will lead to huge economic loss for the state and the country.

Figure 1 is not indicated in the text. Map quality should be improved.

Authors’ response

The figure 1 has been indicated and map quality has improved.

Authors are requested to briefly explain the rationale of selected parameters for
each component of risk.

Authors’ response

As suggested by the reviewer, the statement is added in line 290 to 293.

Figure 2: resolution should be increased.

Authors’ response

The figure resolution has increased.

Section 2.3: In my impression, this section should be shortened, and the current
version is too descriptive. Please take advantage of using statistical graphs/table
in support of your text. Map quality should be improved.

Authors’ response

As suggested by the reviewer, the section 2.3 has reduced.

Section 2.4.1: Authors have commented that the intensity of a cyclone directly
impacts the magnitude of the storm surge, precipitation levels, wind velocity….
However, they just considered rainfall and ignored storm surge, and wind hazard.
The rationale must be declared in a clear manner.

Authors’ response

The parameters considered are the primary parameters that are adding the vulnerability of the region. Here the wind hazard will be considered as the cyclone intensity. Whereas the storm surge is the resultant of the cyclone which is not a contribution to cyclone i.e. adding or decreasing the impact of the cyclone. Hence, the storm surge is not included in the factors.

L301-302: To determine the average frequency….

Not clear.

Authors’ response

These lines are updated in the manuscript in line no. 315.

Figure 4: How did you prepare this? It seems authors analyzed hazard to a
specific distance of inland from coast. Every detail of preparing hazard map
should explained. Map quality should be improved.

Authors’ response

As suggested by the reviewer, the hazard map preparations has been included in the manuscript section 2.4.1. Quality of the map has increased.

L333-338: Authors are requested to simplify their statement in the method section.
Here, you should explain your method and relevant rationale not theoretical
concept.

Authors’ response

As suggested by the reviewer, the method has been discussed and the explanations on the theoretical concepts is reduced.

L344: What did you mean by directing Fig. 2?

Authors’ response

It is figure 5f and the correction is carried out in the manuscript.

L344-346: Changes in…

Repetitive

Authors’ response

The repetitive lines are deleted.

Figure 5, 6, 7: Again, how did you prepare these? Map quality should be improved.

Authors’ response

The map preparation process is explained in the manuscript section 2.4. Quality of the image is enhanced.

L389: Distance from roads…

Which type of road you have considered? Any earthen road should not be
considered as good condition, although you may find short distance from the
earthen road.

Authors’ response

The road considered in the study are major roads connecting the places comprising mainly of Bitumen and Cement concrete roads.

Section 2.3: AHP calculation formula is widely known. I suggest to remove this
and just basic understanding can be discussed. What did you mean by regional
vulnerability index? How did you classify each factor and weight them
accordingly? Table 2 should be improved such as unit of classification should be
included in.

Authors’ response

As suggested by the reviewer, the AHP calculation formula is removed. It is vulnerability index. The classification of the factors and weights are assigned using the experts’ opinion and the literature reviews. The unit of classification is updated in the Table 2.

Conclusion

Although authors briefly discussed their limitation. I think there are many major
issues should be declared too. For example, hazard map lacks several important
components including storm surge, 10m surface wind/gust wind which are greatly
discussed in the field of tropical cyclone studies. Also, meteorological parameters
such as size and translation speed of TC, coastal geometry and bathymetry are
prominent factors to determine the hazard intensity poses by a tropical cyclone.
Please consider citing the following relevant studies and declare the limitation.

Authors’ response

Authors’ partially agree to the reviewer comments. Meteorological parameters like size and the translation speed of TC’s are not included in the study and is included. Whereas the wind speed is given as cyclone intensity and the storm surge is the resultant of the cyclone, which do not change or affect the cyclone movement and their damages. It’s the aftermath effect of the cyclone which comes under the vulnerability of the coast. The end product of the research is to create a multi hazard map by integrating various aspects that are affecting the coast like coastal flooding, coastal physical vulnerability, climate change, and cyclone. Hence, in order to reduce the doubling effect of the variable, storm surge parameter is not taken into account.

1. 
   Gori, A., Lin, N. & Xi, D. Tropical cyclone compound flood hazard assessment:
   from investigating drivers to quantifying extreme water levels. Earths Future 8,
   e2020EF001660 (2020)
2. 
   Alipour et al., 2022 A. Alipour, F. Yarveysi, H. Moftakhari, J.Y. Song, H.
   Moradkhani. A multivariate scaling system is essential to characterize the tropical
   cyclones' risk Earth's Future, 10 (5) (2022), Article e2021EF002635
3. 
   Islam, M.R., Lee, CY., Mandli, K.T. et al. A new tropical cyclone surge index
   incorporating the effects of coastal geometry, bathymetry and storm information.
   Sci Rep 11, 16747 (2021). https://doi.org/10.1038/s41598-021-95825-7

Reviewer 3 Report

Please see the attached document.

Comments for author File: Comments.pdf

Minor edits required.

Author Response

Review of Multi-criterion analysis of Cyclone Risk along the Coast of Tamil Nadu, India – A Geospatial Approach.

Authors: Saravanan et al.

This manuscript is interesting and provides a reasonable approach to combining a variety of known social and physical variables leading to cyclone risk. I think the manuscript is worthy of further consideration after major revisions. I found the graphics difficult to read, as I describe below, which may be a rendering of the .pdf. I did my best but I do feel the authors need to properly describe their graphics within the manuscript. Quite a few were not even mentioned in the text at all (though, to be sure, there is a place for them). I think the authors need to spend a little more time helping the reader interpret the graphics to make it easier to understand how the variables fit together.

Line 38 – only those in the North Atlantic are classified by the SSHWS. Please specify.

Authors’ response

Authors agree to the reviewer comments, the statement has been updated in line 39.

Line 43 – more frequent is based on geographic region – you might phrase it as an increased

frequency of more severe events.

Authors’ response

As suggested by the reviewer, the sentence is rephrased has been updated in line 48.

Line 46 – US dollars?

Authors’ response

Yes, the values are given in US Dollars and updated in the manuscript has been updated in line 55.

Line 49 – lower case tropical (same in 52)

Authors’ response

As suggested by the reviewer, the word is rewritten in lower case.

Line 64 – start new paragraph since you are discussing vulnerability now

Authors’ response

As suggested by the reviewer, the changes has been incorporated has been updated in line 73.

Line 72 – what risk assessment?

Authors’ response

It is cyclone risk assessment and has been updated in the manuscript has been updated in line 80.

Line 170 -needs a citation

Authors’ response

As suggested by the reviewer, the citation has been incorporated in line 198.

Line 171 - while true, I’m not sure why tsunamis are being brought in. Not relevant to the

discussion.

Authors’ response

The authors tried to discuss the stress that the regions coastal environment is facing and the resultant impact of any disaster happening in this region of coast.

Figure 1 is not mentioned in the main body of the manuscript. It fits into the discussion prior to its placement in the document. The figure caption needs more information related to the zones.

Authors’ response

As suggested by the reviewer, figure 1 is incorporated in the text. The zone information is updated in the manuscript in line 171-180.

Unfortunately, all of the figures are very blurry in the .pdf rendering. I’m sure they aren’t on the author’s side, but I cannot see any geographic names at all. I cannot see axes, either.

Authors’ response

Yes, we uploaded high quality figures in the manuscript. We think that while rendering pdf there was some problem. Once again we will try to upload good quality figures.

Line 181 – you already defined GIS

Authors’ response

The statement has been changed.

Table 1 – Indian Metrological Department? I think it should read Meteorological. And is IMD by rainfall the acronym for this? Please include when first mentioned.

Authors’ response

Yes, it is meteorological. Indian Metrological Department is abbreviated as IMD and is mentioned when using it in its first occurrence.

Figure 2 – is this a schematic or are the bottom Risk with/out mitigation graphics something we should be able to take information from at this point? I am asking because they are small. If for schematic purposes – then they are OK (minus that they are blurry for me), but if I need to be able to read them clearly, they need to be a bit bigger. There is a lot of unused white space in the graphic. Maybe increase the size and fill up the space regardless.

Authors’ response

It is just the schematic image of the final results for the flowchart purposes. Those flow chart has been redrawn and the schematic maps were removed. 

I think you need to make a clearer statement that the study is about Tamil Nadu when you introduce Figure 3b. You mention it is one of the most devastated areas but along with other locations. Are those other locations included in Figure 3b? It is hard for me to tell.

Authors’ response

As suggested by the reviewer, the statement is incorporated in the section 2.3 line 228.

Four paragraphs starting line 203- these paragraphs read like bulleted statements – one right after the other describing different events. Can you try and make it more of a summary? It is hard to determine what the reader is supposed to get out of this. Maybe break them up based on decades?

Authors’ response

As suggested by the reviewer, the paragraph is rewritten between lines 234-281.

Line 224 – lower case originated

Authors’ response

The suggestions has been carried out.

Line 276 – were gathered

Authors’ response

The suggestions has been carried out.

Figure 4 – is intensity here the average intensity recorded? Maximum intensity? Average maximum intensity?

Authors’ response

It is the average maximum intensity.

Figure 4 b – is this the total number in the time period? The caption needs more specifics. 4c – maximum rainfall? Total accumulated across all events? Maximum experienced in the region?

Authors’ response

Yes, it is the total number in the specified time period. It is written in the methodology section. 4c is the maximum average rainfall from 1980 to 2021.

Line 326 – the first line of this sentence belongs in the previous paragraph.

Authors’ response

As suggested by the reviewer, the correction is carried out.

Figure 5 is not mentioned in the main manuscript text. It might be my copy, but I’m not seeing much variation in Figure 5e.Do you need all of the legend present? The color choice in Figure 5d doesn’t seem to represent elevation – more like temperature.

Authors’ response

As suggested by the reviewer, the figure 5 is mentioned in the updated manuscript. The colour of the slope and elevation is also changed.

Line 355 – social geographic? Some of your previous vulnerability factors are physical geography based (that is, proximity to streams), so you should specify these are more demographic variables.

Authors’ response

Yes it is physical geography based and are updated in the manuscript in line no 374.

Figures 6 and 7 are not mentioned or described in the main manuscript text. The Fig 6 caption needs more detail. Is it density per km?

Authors’ response

As suggested by the reviewer, the figures are mentioned and the unit are updated in the figure 6.

I really like the inclusion of NVDI – novel consideration with all of the other variables!

Authors’ response

Authors would like to thank the reviewer for their appreciation.

Table 2 – include units for relevant factors

Authors’ response

As suggested by the reviewer, the relevant units are added in Table 2.

Figure 8 – I don’t understand what this is trying to tell me. And Vulnerability is spelled wrong.

Please add some text that describes what these results mean in Figure 8.

Authors’ response

This figure 8 says the percentage of area that are at different levels of risk to cyclones. The spelling of vulnerability is changed.

It would be helpful if you can find a way to include the zone information on the maps in Figure

9. You refer to them so frequently, it would be helpful.

Authors’ response

As suggested by the reviewer, this information is added.

Line 478 – should this read vulnerability map?

Authors’ response

Yes, it is vulnerability map and is updated in the manuscript.

Figure 11 – I’m a little confused here – if a is the map with mitigation, why is the risk increasing in some places? I’m looking toward the very southwest of the map and the peninsular region in the near central zone (I apologize for lack of names – I cannot read them).

Authors’ response

Yes, the risk is increasing without mitigation. Explanation for this is written in the discussion section in line no. 685-693.

Figure 13 – can you provide any context for geographic location for these photos

Authors’ response

As suggested by the reviewer, the geographic locations provided in the caption.

Reviewer 4 Report

The paper presents a tropical cyclone risk analysis that incorporates hazard, vulnerability, exposure, and mitigation with the help of GIS and AHP techniques. It is a suitable topic for MDPI Internatinal Journal of Geo-Information. Therefore, I would recommend a revision following my comments below.

• Figures have low resolution.
• Figures 1, 5, 6, and 7 are not mentioned in the text.
• Figure 3: what was the period of time analysed to create this figure ?
• Table 2: The "AHP weight for factors" related to "Vulnerability" and "Exposure" are not totalizing 100%. Please correct or explain it.
• Table 2 and Figure 8 must be better discussed and explained in the text.
• Validation section should be improved.
• The Conclusions must be more explored, especially discussing more the paper’s novelty and applicability elsewhere.

Author Response

4    Comments and Suggestions for Authors

The paper presents a tropical cyclone risk analysis that incorporates hazard, vulnerability, exposure, and mitigation with the help of GIS and AHP techniques. It is a suitable topic for MDPI Internatinal Journal of Geo-Information. Therefore, I would recommend a revision following my comments below.

Figures have low resolution.

Authors’ response

As suggested by the reviewer, the figures are updated.

Figures 1, 5, 6, and 7 are not mentioned in the text.

Authors’ response

As suggested by the reviewer, the figures are mentioned.

Figure 3: what was the period of time analysed to create this figure ?

Authors’ response

Major cyclone crossed India and all cyclonic storms crossed in Tamil Nadu between 1980 and 2021 are shown in figure 3. The time period is mentioned in the caption.

Table 2: The "AHP weight for factors" related to "Vulnerability" and "Exposure" are not totalizing 100%. Please correct or explain it.

Authors’ response

As suggested by the reviewer, the weights are totalized. This issue was due to the misalignments in the parameters between the Vulnerability and Exposure in the table. It is corrected now.

Table 2 and Figure 8 must be better discussed and explained in the text.

Authors’ response

Table 2 is discussed in the results section whereas the Figure 8 is explained by dividing it in zone wise in the results section from section 3.1 to 3.5.

Validation section should be improved.

Authors’ response

As suggested by the reviewer, the validation section has been improved

The Conclusions must be more explored, especially discussing more the paper’s novelty and applicability elsewhere.

Authors’ response

As suggested by the reviewer, the conclusion section is explained about the novelty, limitation, and applicability.

Round 2

Reviewer 3 Report

I thank the authors for addressing each of my concerns. I no longer have remaining reviews. I think the manuscript is ready for publication (the graphics were so much clearer this time!)

Author Response

We are highly obliged for the time and effort you and the reviewers put in to provide the suggestion for enhancing the manuscript.

Reviewer 4 Report

The paper presents a tropical cyclone risk analysis that incorporates hazard, vulnerability, exposure, and mitigation with the help of GIS and AHP techniques. It is a suitable topic for MDPI Internatinal Journal of Geo-Information. The manuscript has been adequately revised, nevertheless I would still recommend a revision following my comments below.

• Figure 1 has still low resolution.
• Table 2 must be better discussed and explained in the text.

Author Response

We are highly obliged for the time and effort you and the reviewers put in to provide the suggestion for enhancing the manuscript.

We have incorporated the changes suggested by the reviewers and have highlighted in red accent in the revised manuscript.