Tidal flood area mapping in the face of climate change scenarios: case study in a tropical estuary in the Brazilian semi-arid region

Araújo, Paulo Victor N.; Amaro, Venerando E.; Aguiar, Leonlene S.; Lima, Caio C.; Lopes, Alexandre B.

doi:https://doi.org/10.5194/nhess-21-3353-2021

Articles | Volume 21, issue 11

https://doi.org/10.5194/nhess-21-3353-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Remote sensing and Earth observation data in natural hazard...

https://doi.org/10.5194/nhess-21-3353-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 11

Research article

|

09 Nov 2021

Research article |

| 09 Nov 2021

Tidal flood area mapping in the face of climate change scenarios: case study in a tropical estuary in the Brazilian semi-arid region

Paulo Victor N. Araújo, Venerando E. Amaro, Leonlene S. Aguiar, Caio C. Lima, and Alexandre B. Lopes

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Final revised paper (published on 09 Nov 2021)
Preprint (discussion started on 08 Apr 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'omments', Anonymous Referee #1, 13 May 2020
- AC1: 'Response to Referee#1', Paulo Araújo, 10 Jun 2020
  - AC2: 'Revised manuscript', Paulo Araújo, 10 Jun 2020
RC2: 'Referee Comment', Anonymous Referee #2, 21 May 2020
- AC3: 'Response to Referee#2', Paulo Araújo, 11 Jul 2020
- AC4: 'Revised manuscript post RF#1 and RF#2', Paulo Araújo, 11 Jul 2020

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (14 Jul 2020) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (14 Jul 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Jul 2020) by Paolo Tarolli

RR by Anonymous Referee #1 (22 Jul 2020)

RR by Anonymous Referee #2 (19 Aug 2020)

Suggestions for revision or reasons for rejection

LINE 21: remove ‘area’

Line 64: ‘to develope and apply’

LINES 95-99: Is the reduction level the ‘lower astronomical tide’? If yes please rename it since lower astronomical tide is an internationally used term for the datum used in Navigation maps. If it is not please explain what is the difference.

LINE 100: what do you mean with ‘mean quadrature of high tides’. Is this the mean neap tides? What about the mean spring tides that are more relevant to flooding conditions.

LINE 120: remove ‘(type of focus flooding of this job).’ The term job is not appropriate, work or article is better, but I believe it is not needed since now it is explained before.

LINE 120: Reference the recent reports.

LINES 215-220: IS the IBGE a climate change scenario or 2.1mm/year is the measured sea level rise in the area using tidal gauges? If it’s the latter the two values are not representing the same conditions. The 2.1 mm/year is the current condition not a climate change scenario.

LINES 241-264: I have various consideration regarding the hazard Classes.
• As I stated in previous review the classes are in a reverse order. The authors reply saying that ‘for this study, the highest weights correspond to small rise’; however, in LINE 247 they state ‘Hazard map is the likelihood of the process occurring with magnitude M (destructive potential) and…’. First of all Hazard mapping is a spatial representation of the hazard not a value. There is a direct inverse relationship between hazard magnitude and hazard probability. If the authors want to work with hazard probability they should estimate it, but this is not hazard is hazard probability. This probability is related with a return period but the authors in Table 1 and 2 refer to Hazard and not Hazard probability. Also in Table 4 levels were provided but they were not converted to probability. A key parameter for that is determining a threshold of water level in which damage is considered.
• Also the combinations of SLR for 2100 for different RCPs for local SLR rate and return periods are confusing because different temporal scales are mixed. A hazard map should provide levels of probability for a fixed time period.
• Finally in LINE 64 the authors mention that develop and apply a method; however no method development is presented in the paper just an application. If a new methodology is developed the stages and how the weight are obtained needs to be explained.

LINES 275-294: Regarding the return period of the tidal level, I believe that the application of an extreme value statistic in a deterministic parameter like the tidal level is an error. The authors state that they use the tidal behavior parameter. I am not sure what this means; the authors will need to explain this in the text. I am just stating that even in Figure 5B it is obvious that the tidal level has a maximum at 2.85, the tidal levels will repeat themselves every 19.8 years so for a return period of 20 years you just need to select the maximum tide recorded the past 19.8 years.

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ED: Reconsider after major revisions (further review by editor and referees) (25 Aug 2020) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (15 Sep 2020) Manuscript

ED: Referee Nomination & Report Request started (04 Oct 2020) by Paolo Tarolli

RR by Anonymous Referee #2 (22 Dec 2020)

Suggestions for revision or reasons for rejection

The authors have undertaken the majority of my suggestion. The article is significantly improved. However I home some additional comments regarding the response of the authors:

1. To my question if the reduction level is the lowest astronomical (LAT) tide used as common reference datum for navigation maps the authors answered No, but they explanation they provide ´RL is level that corresponds to the 30 average of low tides of syzygy´, suggest that the RL is a chart datum estimation similar to LAR or to the mean lower low water (MLLW) used by the US Navy. The importance here is to provide to the reader an idea of the reduction level is.

2. To my question if the IBGE is a climate change scenario they replied Yes but the text provided in the document ´The latter, result of reports on data from IBGE tidal network ´ suggest that IBGE projection is not a climate change scenario but the measured sea level change in the region. Both can be used but the IBGE data is a completely different estimation for sea level rise for the year 2100. It is not a better estimator it is a simple linear projection of the past measurement.

3. The line 207: ´In all rate of sea level rise in scenarios used, are from robust modelling of sea level projection under face climate change ´ is grammatically incorrect and should be changed.

4. As for the use of a return period statistics to the Astronomical tide I am still not convinced. The only uncertainty about the astronomical tide in the future is not the maximum level but the timing of the astronomical tide related with the meteorological tide. Also, as it can be observed in Figure 5B the fitting applied (linear) is not a good explanation for the data that, as expected, present a level of the maximum tidal levels after the 5 years return period value. A combined extreme value analysis of the total level (astronomical+meteorological) has a purpose.

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ED: Reconsider after major revisions (further review by editor and referees) (03 Jan 2021) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (27 Jan 2021) Author's response Author's tracked changes Manuscript

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

RR by Anonymous Referee #2 (12 Feb 2021)

RR by Anonymous Referee #3 (18 Mar 2021)

Suggestions for revision or reasons for rejection

The paper presents a study focused on tidal flood risk mapping. The proposed case study is the PiranhasAçú Estuary, the northern portion of Rio Grande's state do Norte, Brazil. The case study is interesting, and the topic is important. Unfortunately, the paper has some strong limitations that hamper the publication as it is. The first strong limitation is the presence of several problems with the language. An English native speaking revision is mandatory.
In the following some comments and suggestions:
line 60: the introduction is well written and argued; I suggest the author consider to add a sentence to describe better the topic of the manuscript (e.g. the dataset used and what elements of this paper are innovative and should be evaluated by readers).
Line 68: in this manuscript, I found several problems related to incorrect use of the language; for this reason, I strongly recommend a revision by English native speaking. For example, I am not sure about the meaning of “rainy late to autumn”. I do not think that the reviewer's duty is the revision of the language of the manuscript, but I believe that a substantial revision is mandatory in this paper.
Line 110: in figure two, are mentioned several municipalities. I suggest the author add some information about the areas involved in tidal floods that are mentioned in this part of the manuscript. I suppose, for example, that the flooded areas are part of Porto de Mangue and Macau municipalities.
Chapter 3.4: the description of adopted scenarios seems to be too synthetic; I suggest the authors revise the chapter and describe better the adopted dataset.
Figure 6: it is not easy for readers to have an idea of the position of the city of Macau mentioned in the description of figure 6b and 7. Figure 6b: in the lower part of the image, there is the river (in black), but the river disappeared in the corner of the image that is red. I do not know if this is an error or some infrastructure covers the river. Figure caption: I suppose, as mentioned in the text, that the cemetery area cannot be flooded, according to the model; I think that this important result should be mentioned in the figure caption because this area does not belong to an extremely low flood hazard level but another (not mentioned) category.
Figure 7: I not sure that this image is important and representative
Line 295: “It is important to mention that the land on which the local cemetery is in the urban area of Macau is one of the few urban sectors in the city not to suffer from tidal flood scenarios.” This result is interesting, but I think that the description is too limited. I believe that readers want to know if the area is not affected by the presence of a local topographic effect or other elements.
Figure 9: I do not understand why this map is presented at the end of the paper. The map of land use is presented at the end of the paper, but it is mentioned for the first time in chapter 3.
Lines 295 – 305: in ten lines, the authors mentioned three figures (9-10-11) without a real explanation of the obtained results. I do not think that figure 9 is really necessary at the end of this chapter ad that, if the authors want to present it, they could do it before.
An accurate description of the results proposed in figure 10 is missing. The sentence of line 304 cannot be considered acceptable.
Chapter 4.3: this is the most important result of the paper, and the author described it in 5 lines! As suggested in figure 10, this part of the manuscript should be explained better.

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ED: Publish subject to minor revisions (review by editor) (15 Apr 2021) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (27 Aug 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (03 Sep 2021) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (09 Oct 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (14 Oct 2021) by Paolo Tarolli

AR by Paulo Araújo on behalf of the Authors (15 Oct 2021) Manuscript

Short summary

The approach of this work is a tidal flood risk mapping methodology for climate change scenarios in a semi-arid region with a strong environmental and social appeal. The study area has been suffering severe consequences from flooding by tides in recent years. High-geodetic-precision data, together with tidal return period statistics and data from current sea level rise scenarios, were used. This case study can serve as a basis for future management actions and as a model to be copied.