Mesoscale simulation of typhoon-generated storm surge: methodology and Shanghai case study

Dong, Shuyun; Stephenson, Wayne J.; Wakes, Sarah; Chen, Zhongyuan; Ge, Jianzhong

doi:https://doi.org/10.5194/nhess-22-931-2022

Articles | Volume 22, issue 3

https://doi.org/10.5194/nhess-22-931-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/nhess-22-931-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 22, issue 3

Research article

|

21 Mar 2022

Research article |

| 21 Mar 2022

Mesoscale simulation of typhoon-generated storm surge: methodology and Shanghai case study

Shuyun Dong, Wayne J. Stephenson, Sarah Wakes, Zhongyuan Chen, and Jianzhong Ge

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Final revised paper (published on 21 Mar 2022)
Preprint (discussion started on 15 Mar 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Meso-scale Simulation of Typhoon Generated Storm Surge: Methodology and Shanghai Case Study', Anonymous Referee #1, 01 Jun 2017
- AC1: 'Response to Reviewer One', Wayne Stephenson, 10 Dec 2019
RC2: 'Meso-scale simulation of typhoon generated storm surge: Methodology and Shanghai case study', Anonymous Referee #2, 06 Jun 2017
- AC2: 'Response to Reviewer Two', Wayne Stephenson, 10 Dec 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by editor and referees) (23 Dec 2019) by Bruce D. Malamud

AR by Wayne Stephenson on behalf of the Authors (01 Feb 2020)

ED: Referee Nomination & Report Request started (02 Mar 2020) by Bruce D. Malamud

RR by Brian Finlayson (01 Apr 2020)

Suggestions for revision or reasons for rejection

Overall assessment.

This is a very useful paper in that it is set up to use minimal data. In many cases where data for sophisticated models are not available the models are run anyway using artificial data. I am familiar with cases where this has been done in China and I’m sure it is done elsewhere too.

The paper provides a methodology for a more accessible process to model storm surges in coastal cities that will be very useful in many tropical locations.

Specific issues.

Given that the stated intention of this paper is to present a “general easy-adopted model with reasonable accuracy that could be implemented for planning purposes” (line 13), I’m not sure that all the material covered in the literature review is necessary.

There are many minor issues with the English used in the paper. None are serious enough to obscure the intended meaning but a check through the paper by a native English speaker would improve the quality of the text.

The abbreviation SC-TSSM first appears in line 153 but what it actually stands for is not given until line 320.

This sentence, at line 153, seems to associate Smagorinsky’s paper with the SC-TSSM: “The horizontal eddy viscosity is specified as a constant of 0.8 in the SC-TSSM (Smagorinsky 1963).” Of course, no such association exists, only this value for horizontal eddy viscosity comes from Smagorinsky. The confusion here is heightened by the fact that at this point in the paper the initials SC-TSSM has not been defined.

In line 154 it is stated that the height of the sea wall along the Shanghai coast is set at 6.37 m relative to mean sea level. No explantion is given for this, so how was this number decided?

Line 169-171: “Young and Sobey (Young and Sobey 1981), Holland (Holland 1980), Holland for double vortex (Harper and Holland 1999), and Rankine 170 (Rankine 1872).” This would be better put as: “Young and Sobey (1981), Holland (1980), Holland for double vortex (Harper and Holland 1999), and Rankine (1872).”

Line 245: Given what is stated here about Typhoon Wipha, it is difficult to see how it could have passed to the west of Shanghai during landfall.

In Section 4.1 map data are said to be supplied by East China Normal University. I would be very surprised if ECNU is a producer of maps and presumably these came out of the ECNU Library. What is the origin of the maps? This information is essential for readers who may wish to access the same maps.

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RR by Anonymous Referee #4 (03 Sep 2020)

Suggestions for revision or reasons for rejection

The authors use MIKE-21 to simulate past extreme storms in the area of Shanghai. The science seems to be good but the presentation of the paper does not allow to follow really the work.
The structure is rather confusing with a lot of repetitions, and could be improved a lot. I would recommend structuring the paper as follows:
1. Intro
2. Study area
3. Description of events simulated
4. Data and Methods
a. Model description
b. Data (topography, bathymetry, water levels)
5. Results
6. Discussion
7. Conclusions
That would allow avoiding the repetitions of the methodology existing now between sections 3 and 4.
When the authors describe the models they need to try to make it in a more transparent way. Normally unstructured grids are used to avoid nesting, but here they mention that both are taking place. This needs to be explained and the authors need to provide a map showing the domains of the nested models.
Also the authors need to explain if they consider waves in their simulations and if not to justify why.
I find the acronyms confusing. TSSM includes SC-TSSM and HI-TSSM?
What is the resolution on the terrestrial part of the domain where inundation takes place?
Page 11: paragraph 2 ’In China’: this feels like discussion and not results
Page 12, line 4. I don’t agree. Large scale simulations can be very computationally expensive, depending on the resolution, also the authors could provide examples from other studies (see papers from Vousdoukas, Hemer, Muis, Montblanc, etc)
Page 12, lines 20-40: The two paragraphs repeat each other. Anyway, I don’t see the relevance, commercial or not, most models have similar physics, and it’s all about calibration.
Figure 4: I would make no inundation transparent, also panel a and b seem identical, can the authors confirm that there has been no mistake?
The validation is very poor. The authors could present statistics to show skill in simulating water levels (RSME, BIAS), as well as scatter plots in addition to Fig 3. In case there are observations of the flooded are inundation could be validated with Hit, Miss, False ratios (e.g. https://nhess.copernicus.org/articles/16/1841/2016/). Otherwise, presenting a flood model without any ground truth data is pointless and the authors should focus the paper on the storm surge modelling.

Hide

ED: Reconsider after major revisions (further review by editor and referees) (06 Oct 2020) by Bruce D. Malamud

Dear Drs. Shuyun Dong, Wayne J. Stephenson, Sarah Wakes, Zhongyuan Chen, and Jianzhong Ge:

Thank you for the re-submission of your manuscript “Meso-scale Simulation of Typhoon Generated Storm Surge: Methodology and Shanghai Case Study” and also for your patience while I found suitable reviewers for this resubmission.

Two reviewers have now provided detailed reviews which are appended below my signature. One reviewer recommended minor revisions and the other major revisions. Both reviewers state the science is good although the second reviewer in the final paragraph does have a comment about validation, which I would be curious about how you might address, without significantly reworking the paper. Both reviewers also comments on English and structure.

Based on these comments, would you please provide a revised manuscript.

Along with this will you provide an ‘author’s reply’ to the reviewers, addressing each point and how you have reflected changes in the manuscript (or if you disagree, why, and how you have addressed in your manuscript the point to include the perspective of the reviewer). Please can you also include a track changes document between the old manuscript and the new one. The two documents can be saved as PDFs and combined into one document for the upload.

I look forward to seeing the next version of your manuscript which I will then potentially send out to one of the previous reviewers.

Regards
Bruce D. Malamud
NHESS Executive Editor
[Professor of Natural & Environmental Hazards, King’s College London]

Referee #3: Brian Finlayson [Non-Anonymous during Peer-Review]

Overall assessment.

This is a very useful paper in that it is set up to use minimal data. In many cases where data for sophisticated models are not available the models are run anyway using artificial data. I am familiar with cases where this has been done in China and I’m sure it is done elsewhere too.

The paper provides a methodology for a more accessible process to model storm surges in coastal cities that will be very useful in many tropical locations.

Specific issues.

Given that the stated intention of this paper is to present a “general easy-adopted model with reasonable accuracy that could be implemented for planning purposes” (line 13), I’m not sure that all the material covered in the literature review is necessary.

There are many minor issues with the English used in the paper. None are serious enough to obscure the intended meaning but a check through the paper by a native English speaker would improve the quality of the text.

The abbreviation SC-TSSM first appears in line 153 but what it actually stands for is not given until line 320.

This sentence, at line 153, seems to associate Smagorinsky’s paper with the SC-TSSM: “The horizontal eddy viscosity is specified as a constant of 0.8 in the SC-TSSM (Smagorinsky 1963).” Of course, no such association exists, only this value for horizontal eddy viscosity comes from Smagorinsky. The confusion here is heightened by the fact that at this point in the paper the initials SC-TSSM has not been defined.

In line 154 it is stated that the height of the sea wall along the Shanghai coast is set at 6.37 m relative to mean sea level. No explantion is given for this, so how was this number decided?

Line 169-171: “Young and Sobey (Young and Sobey 1981), Holland (Holland 1980), Holland for double vortex (Harper and Holland 1999), and Rankine 170 (Rankine 1872).” This would be better put as: “Young and Sobey (1981), Holland (1980), Holland for double vortex (Harper and Holland 1999), and Rankine (1872).”

Line 245: Given what is stated here about Typhoon Wipha, it is difficult to see how it could have passed to the west of Shanghai during landfall.

In Section 4.1 map data are said to be supplied by East China Normal University. I would be very surprised if ECNU is a producer of maps and presumably these came out of the ECNU Library. What is the origin of the maps? This information is essential for readers who may wish to access the same maps.

Referee # 4 (anonymous)

The authors use MIKE-21 to simulate past extreme storms in the area of Shanghai. The science seems to be good but the presentation of the paper does not allow to follow really the work.

The structure is rather confusing with a lot of repetitions, and could be improved a lot. I would recommend structuring the paper as follows:

1. Intro
2. Study area
3. Description of events simulated
4. Data and Methods
a. Model description
b. Data (topography, bathymetry, water levels)
5. Results
6. Discussion
7. Conclusions

That would allow avoiding the repetitions of the methodology existing now between sections 3 and 4.

When the authors describe the models they need to try to make it in a more transparent way. Normally unstructured grids are used to avoid nesting, but here they mention that both are taking place. This needs to be explained and the authors need to provide a map showing the domains of the nested models.

Also the authors need to explain if they consider waves in their simulations and if not to justify why.

I find the acronyms confusing. TSSM includes SC-TSSM and HI-TSSM?

What is the resolution on the terrestrial part of the domain where inundation takes place?

Page 11: paragraph 2 ’In China’: this feels like discussion and not results
Page 12, line 4. I don’t agree. Large scale simulations can be very computationally expensive, depending on the resolution, also the authors could provide examples from other studies (see papers from Vousdoukas, Hemer, Muis, Montblanc, etc)
Page 12, lines 20-40: The two paragraphs repeat each other. Anyway, I don’t see the relevance, commercial or not, most models have similar physics, and it’s all about calibration.
Figure 4: I would make no inundation transparent, also panel a and b seem identical, can the authors confirm that there has been no mistake?

The validation is very poor. The authors could present statistics to show skill in simulating water levels (RSME, BIAS), as well as scatter plots in addition to Fig 3. In case there are observations of the flooded are inundation could be validated with Hit, Miss, False ratios (e.g. https://nhess.copernicus.org/articles/16/1841/2016/). Otherwise, presenting a flood model without any ground truth data is pointless and the authors should focus the paper on the storm surge modelling.

Hide

AR by Wayne Stephenson on behalf of the Authors (20 Nov 2020) Manuscript

ED: Referee Nomination & Report Request started (30 Jul 2021) by Paolo Tarolli

RR by Brian Finlayson (11 Aug 2021)

Suggestions for revision or reasons for rejection

As I said in my review of a previous version of this paper, the focus on using “less data rich approaches to flood modelling of coastal mega-cities where there is often a paucity of data” (lines 38+39) is commendable though the process is not necessarily confined to coastal mega-cities. It points the way to making useful storm-surge predictions in densely populated coastal areas, especially in the less wealthy parts of the globe.

There are language errors throughout the text. While they do not prevent the reader from following the argument, they should be corrected given that two of the authors are English speakers. One notable aspect of the language is the persistent use of “typhoon” as being both singular and plural. According to the Oxford English Dictionary “typhoon” has the plural form “typhoons”.

Many of the figures in the version of this paper sent to me contain collections of dots that appear to have no connection to the material in the figures.

In Section 4.1 it is stated that “topographical data ……… was provided by the East China Normal University”. This is a very vague description of the origin of this data. Further, it is stated that “The topographical data was extracted from the digital elevation model of Shanghai with a 5 m spatial resolution.” This is presumably the same data as supplied by ECNU. So whose data is it that has been stored and provided by ECNU? There also should be a more precise description of the source of the bathymetry than that it was downloaded from NOAA. Also, this is the only point in the paper where NOAA is mentioned so all the readers are presumably meant to know that NOAA stands for the National Oceanic and Atmospheric Administration in the United States Department of Commerce (and not the name of the first man mentioned in the Bible).

To add to the confusion, in the paragraph starting at line 253, the topographic data provided by ECNU is first claimed to have a spatial resolution of 5 m and later this is given as 1 km.

In the key to Figure 3 the map in (a) has “differing resolution ranging, from 10 – 100 km”, while in the paragraph above, starting at line 253 this range is given a 1-100km.
The key to Fig 8 should give either the source of the maps or the source of the data used to construct them.

Line 373. Figure referred to should be Fig 9(c)

I have reviewed previous versions of this paper and I am satisfied that the paper is now ready for publication though I raise 2 points about this version.

1. In the copy of the paper sent to me Figures 1, 4, 5, 6 and 7 all contain parts of the material plotted that lie outside the boundaries of the figure.
2. The authors use “typhoon” as a plural word. This is incorrect.

Brian Finlayson, University if Melbourne

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RR by Brian Finlayson (02 Nov 2021)

ED: Reconsider after major revisions (further review by editor and referees) (12 Nov 2021) by Paolo Tarolli

AR by Wayne Stephenson on behalf of the Authors (23 Nov 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (24 Nov 2021) by Paolo Tarolli

RR by Brian Finlayson (25 Nov 2021)

ED: Publish as is (21 Feb 2022) by Paolo Tarolli

AR by Wayne Stephenson on behalf of the Authors (21 Feb 2022)

Short summary

Mesoscale simulation provides a general approach that could be implemented to fulfill the purpose of planning and has relatively low requirements for computation time and data while still providing reasonable accuracy. The method is generally applicable to all coastal cities around the world for examining the effect of future climate change on typhoon-generated storm surge even where historical observed data are inadequate or not available.