Effects of Beach Nourishment Project on Coastal Geomorphology and Mangrove Dynamics in Southern Louisiana, USA

Round 1

Reviewer 1 Report

Please see the attached document.

Comments for author File: Comments.pdf

Author Response

Reviewer 1

Review of: “Effects of beach nourishment project on coastal geomorphology and mangrove

dynamics in southern Louisiana, USA” by Marcelo C. L. Cohen et al.

General comment

The paper investigates the impact of shoreline dynamics driven by beach nourishment on mangroves and salt marshes.

In particular, the authors describe the interactions between the black mangrove dynamics and the shoreline retreat before and after the beach nourishment project in the Caminada-Moreau Headlands around Bay Champagne (Louisiana, USA). The analysis, based on a high-resolution satellite, drone and lidar data collected from 1998 to 2019, is aimed to assess the effect of sea-level rise. The findings of the authors are useful for further applications in coastal engineering,

with particular reference to face sea hazard driven by climate change. The overall scientific importance and relevance of the paper is robust, its implications for further analysis and studies are significant enough. The proposed methodology and discussion are prominent enough and mostly supported by recent references. Some revisions are still in need, in particular as far as the issues below are concerned.

 

Authors: We appreciate the analysis and comments. We have answered each comment individually below.

 

Reviewer 1

Issues

- The paper is not too smooth for reading, due to the lengthy prose. I think by making it a little bit more streamlined it would gain in value.

Authors: The abstract was edited, the presentation of the methods was restructured, and part of the section Results was rewritten to make the work more concise and streamlined.

 

Reviewer 1

- The abstract is too long: I suggest to omit most of the numerical data/results reported therein.

Authors: Sentences of the Abstract have been edited and some numerical data/results were removed.

 

 

Reviewer 1

- Section 2 should be included in Section 1 or in Section 3.

Authors: Section 2 has been included in Section 3 (lines 102 – 120).

 

Reviewer 1

- Section 4.1: too many numerical data within the text.

Authors: Some numerical information has been removed, but we prefer to keep data related to seasonality that are not in Table 1 (lines 255 – 265).

 

Reviewer 1

- I suggest to introduce the storm surges and the effects of sea hazards on coastal areas (e.g. ref. 1).

Authors:  This issue was addressed in the Introduction (lines 61 – 63).

 

Reviewer 1

- Please provide some information about the sea defense structures commonly used to defend the coastal areas (e.g. ref.2), focusing on the target pursued by these measures.

Authors:  Information about the sea defense structures have been added (lines 77 – 80, 404 - 416, 437 – 439, 494 - 498).

 

Reviewer 1

Formerly, sea defence interventions mostly focused on the safety and protection of humans and assets, without taking into account the environmental needs of the land. At present, several maritime policies aim to protect coastal habitats and natural resources, promoting a sustainable use of the land. Nevertheless, environmental degradation threatens coastal areas, mostly due to the impact of the structures built in the last decades, which affect landscape, ecosystems, biodiversity and biological interactions (e.g. ref. 2 and 3). In this context, restored environments and healthy ecosystems are more productive and support a sustainable coastal and sea economy (blue growth) (e.g. ref. 4 and 5). A short overview of this topic could be worthy of interest.

Authors:  We appreciate the information that has been adequately incorporated into the Introduction (lines 61 – 63) and Discussion (lines 498 – 500).

 

Reviewer 1

- It is not clear how the authors validated the retreat measurements with in-field data (e.g. lines 169 – 189).

Authors: Fieldwork with drone and topographic survey allowed to validate topographic data, vegetation types/heights and the shoreline dynamics between Oct/2017 and Nov/2019 obtained by remote sensing. Topographic surveys allowed determining the intertidal and supratidal zones limits during that time interval (lines 159 – 166).

 

Reviewer 1

- Method and findings are certainly interesting. Can the authors discuss a more general validity of the results (e.g. the application of the same method in other areas) ?

Authors: The margin of error of these methods and their applications have been added to the Section Methods (lines 213 – 227) and Discussion (lines 530 – 533).

 

Reviewer 1

- The paper would benefit from a thorough English proofreading.

Authors: A native English speaker revised the text.

 

 

Reviewer 1

References

1) Resio, D., Irish, J., Cialone, M. (2009) “A surge response function approach to coastal hazard assessment - Part

1: Basic concepts” Nat. Hazards. 51. 163-182. 10.1007/s11069-009-9379-y.

2) Maiolo, M., Mel, R.A., Sinopoli, S. (2020) “A Stepwise Approach to Beach Restoration at Calabaia Beach”, Water,

12, 2677; doi:10.3390/w12102677.

3) Ye, G.; Chou, L.M.; Yang, S.; Wu, J.; Liu, P.; Jin, C. (2015) “Is integrated coastal management an effective

framework for promoting coastal sustainability in China’s coastal cities?” Mar. Policy, 56, 48–55.

4) Ostrom, E. (2009) “A general framework for analyzing sustainability of social-ecological systems” Science

325(5939):419–422.

5) Post, J.C.; Lundin, C.G. Guidelines for Integrated Coastal Zone Management, (1996). The World Bank: Washington, DC,USA; Volume 9, ISBN 0821337351.

Authors: These papers were cited in the text. Thanks.

 

We hope to have addressed all comments accordingly. We look forward to having your positive evaluation and acceptance of the revised manuscript.

 

Best regards,

Marcelo Cohen

Federal University of Pará

Rua Augusto Corrêa, 01

Cep: 66075-110, Bairro: Guamá

Belém-Pará

Tel: 91-3201-7478

Cel: 91-8031-1300

E-mail: [email protected]

www.ufpa.br/cpgg

Reviewer 2 Report

Overall, this is interesting research that uses multiple different data sources to examine the effect of a renourishment project on geomorphic habitats (barrier beach/mangrove). I found the introduction interesting, but was lost in the methods and could not follow how the data sources were processed and analyzed. I suggest extensive reorganizing of the methods. The results were well presented, but at times the discussion presented results and the results presented discussion. These sections could use a thorough clean-up, but are otherwise better organized than the methods. In many situations, wording was unclear and there were several instances of typos as well. Overall, I think the paper requires extensive revision, perhaps altering it so that it flows consistently within each section (methods-results-discussion have similar order in the presentation). If revision occurs, I do think this manuscript would be of interest to the readers of Remote Sensing and could be reconsidered for publication, so I do encourage the authors to resubmit. I have added a few notes of suggested revisions or changes below, but this is not an extensive list, just examples of how text/figures/tables could be more concise and clearer to the readers.

 

LINE 53 There appears to be a mix of number notation and author/year notation for citations. This needs to be cleaned up throughout the document.

LINE 55-57 Sand dune response to sea level rise and reduced sediment supply is to migrate. Dune submergence or loss would be “clear evidence” that the beach barrier has “not kept pace” with RSLR. Either explain more clearly why this rate suggests the barriers are not keeping up with RSLR, or reword to something like “clear evidence that the both the shoreline and the beach barrier response to sea level rise and reduced sediment supply is to migrate landward.”

LINE 76 I don’t understand what you mean by “overlapped” muddy flats. Did the beach barriers migrate and replace the muddy flats? “Overlayed” might also be a better term.

LINE 130-132 were these ground-truthing data collected temporally coincident with the Lidar data? How much smaller was the accuracy?

LINE 136 analyses

LINE 150 This is unclear. What “previously identified land cover” data set? What year, source etc?

LINE 168 Header is “D models”. Should this be 3D models?

LINE 172-173 “A high resolution, dense point cloud was executed based on point clouds with point spacing between 3 and 5 cm” I do not understand. A dense point cloud was “executed” from point clouds? Or did you just merge the individual point clouds to create a point cloud that covered the AOI?

LINE 173 How was the point cloud analyzed to remove vegetation? What algorithm is used?

LINE 198 I do not understand “breaking the area and assessed into many small squares”. Do you mean dividing the study area into a grid? If so, is this a uniform grid (uniform X and Y) or non-uniform grid?

LINE 201 These Zones are not indicated on Figure 1b. There is indication in Fig 5. This needs to be clarified.

LINE 209 This could be explained more clearly using “cross shore” and “longshore” I think. You have nine vertical profiles. Seven profiles are cross-shore transects that start landward of the dune ridge and end at the shoreline (perpendicular to the shoreline). Two longshore profiles follow the dune ridge line (generally parallel to the shoreline).

LINE 220 How are you identifying the upper limit of the intertidal zone? Did you digitize from the imagery using a wet-dry line? Clarify.

Table 1 misspelling “data”. It says Dada. What is Mangr? Mangrove?

OVERALL METHODS COMMENT: The methods section is very confusing and disjunct. A table or figure of the different data source and processing steps would help clarify how each remote sensing and other data (Quickbird, drone, lidar, GCPs, etc) is used generate the planialtimetric, (vegetation?), meteorological and oceanographic time series data. Perhaps reordering the methods to match the Results would also help. You end the methods with the oceanographic and flucvial data, but begin the Results with these data. Also, you have two a’ to b’ transects. I recommend reconsidering these labels so they are different. Is there a reason why A-B transect is different than a’ – b’ transect? It is important to indicate why these transects were chosen (random or intentional?) for each analyses and why they are different locations. Perhaps putting them on one map and calling them “vertical profile transects” and “planimetric transects” (or something) and also making it clear in the methods text that the cross-shore profiles are used for sediment volumes and planimetric for measuring shoreline and habitat changes would be helpful.

Fig. 2 The figure description requires more clarity. C) says these are profiles between 1998 and 2019, but only the top two have 1998 profile data. Clarify.

GENERAL RESULTS COMMENT: Many of the values do not have error values, yet the vertical and horizontal accuracy is explicit in the methods. An indication of confidence or error on these measurements would improve these results.

LINE 334-335 “This process caused a loss of ~15.6 ha of wetlands (14.52 ha of saltmarsh and 1.08 ha of mangrove) along 335 the 4-km coastline between 2004 and 2012” This is a discussion statement, not results. Reword to say “This process (sand accumulation) was coincident with a loss of wetlands…” Then you can make this assessment in the Discussion (that the sand accumulation might have caused the loss in wetlands and why this might be so).

Table 2 is really hard to read and compare numbers. Suggest reorganizing to indicate the time interval in the Table description… ie. “Size of mangrove, saltmarsh and sandy flat areas before (2004 – 2012) and after (2012-2019) the beach nourishment project. Then make the table columns Geomorphological Units, Before, After, with subheadings for Gain/Loss. For example,

	Before renourishment		After renourishment
Geomorphological Unit	Gain (ha)	Loss (ha)	Gain (ha)	Loss (ha)
Mangrove
Marsh
Sandy flat

You might also have a column with the overall ratio (before:after). Also note that there is probably too many numbers after the decimal point (would you say your precision is that accurate?). Also, you don’t mention “sandy flats” in the text, I assume you mean the sandy intertidal flat? If so, be consistent with naming, or indicate that you will use both terms “sandy intertidal flat (sandy flat)” or something like that.

LINES 363 – 369. This paragraph reads like Results, not discussion.

LINE 389-390 “Despite the beach nourishment project's effort to stabilize the beach barrier, the Quickbird images, recorded between Jan/2015 and Mar/2019, revealed shoreline retreat in the transects A and B and stability in transects C and D” So, 50% of your transects showed shoreline stabilization. This indicates the renourishment might have been partially successful? But it sounds like you are saying it was not. Explain or clarify.

LINE 391 At this point, just use the zone feature name (supratidal and sandy intertidal flat) since your discussion is focused on the effect on habitats and not arbitrary zones.

LINE 433-435 Citation?

OVERALL DISCUSSION: It is clear from photos/figures that sand fencing was installed, likely to encourage dune growth. You note that dune height increased after renourishment, but when were these sand fences established? Could the sand fences also be the cause of the dune growth (not just the renourishment)? Or were they also present prior to the renourishment? Please add to you discussion (and you might also put this info in the background). I also noted that some of the marsh grasses look evenly spaced, so if vegetation plantings occurred, that is also important to note.

Author Response

June 21, 2021

Dear Melissa Zhu

Assistant Editor

Remote Sensing

Ref: remotesensing-1233010

Title: " Effects of beach nourishment project on coastal geomorphology and mangrove dynamics in southern Louisiana, USA”.

Please find attached the revised version of the paper entitled “Effects of beach nourishment project on coastal geomorphology and mangrove dynamics in southern Louisiana, USA”, by Cohen et al., to the Special Issue "Human–Environment Interactions Research Using Remote Sensing" edited by Nina Lam.

We appreciated all the comments and suggestions provided by the reviewers, which helped us to improve the earlier version of this manuscript. The author and co-authors of this work carefully reviewed the manuscript to clarify all points raised. Changes are all indicated in yellow color in the annotated version that we have attached. Below, we have answered each comment individually.

Reviewer 2

Overall, this is interesting research that uses multiple different data sources to examine the effect of a renourishment project on geomorphic habitats (barrier beach/mangrove). I found the introduction interesting, but was lost in the methods and could not follow how the data sources were processed and analyzed. I suggest extensive reorganizing of the methods.

Authors: The Section Methods was restructured (2.1. Study area, 2.2. Historical oceanographic data, 2.3. Remote sensing, 2.4 Image classification, 2.5. Analyses of spatial data, and 2.6. 3D models ), and part of the text was rewritten (lines 96 – 101,  160 – 164, 169 – 174, 183 – 184, 205 – 208, 212 – 213, 219 - 227, 235 -238, 245 – 253). We have added a Methodology flow chart (Fig. 2) to evidence the sequence of activities and data processing.

 

Reviewer 2

The results were well presented, but at times the discussion presented results and the results presented discussion. These sections could use a thorough clean-up, but are otherwise better organized than the methods.

Authors: Some sentences of the results have been rewritten to make them more concise (lines 291-294, 339 – 341, 360 – 362, 366 – 368, 372 - 373), and Tables 1 and 2 were restructured to facilitate the reading of the nourishment project effects on the studied coast.

Reviewer 2

In many situations, wording was unclear and there were several instances of typos as well.

Authors: A native English speaker revised the text.

 

Reviewer 2

Overall, I think the paper requires extensive revision, perhaps altering it so that it flows consistently within each section (methods-results-discussion have similar order in the presentation). If revision occurs, I do think this manuscript would be of interest to the readers of Remote Sensing and could be reconsidered for publication, so I do encourage the authors to resubmit. I have added a few notes of suggested revisions or changes below, but this is not an extensive list, just examples of how text/figures/tables could be more concise and clearer to the readers.

Authors: We appreciate the comments and criticisms that significantly contributed to improving this work. We have answered each comment individually below.

 

Reviewer 2

LINE 53 There appears to be a mix of number notation and author/year notation for citations. This needs to be cleaned up throughout the document.

Authors: Citations have been corrected throughout the text.

Reviewer 2

LINE 55-57 Sand dune response to sea level rise and reduced sediment supply is to migrate. Dune submergence or loss would be “clear evidence” that the beach barrier has “not kept pace” with RSLR. Either explain more clearly why this rate suggests the barriers are not keeping up with RSLR, or reword to something like “clear evidence that the both the shoreline and the beach barrier response to sea level rise and reduced sediment supply is to migrate landward.”

Authors: This sentence has been rewritten (lines 59 – 61).

Reviewer 2

LINE 76 I don’t understand what you mean by “overlapped” muddy flats. Did the beach barriers migrate and replace the muddy flats? “Overlayed” might also be a better term.

Authors: the landward migration of beach barriers resulted in the burial of muddy tidal flats and degradation of mangrove vegetation in Brazil (Cohen et al., 2018, 2009; Cohen and Lara, 2003) (lines 81 – 83).

Reviewer 2

LINE 130-132 were these ground-truthing data collected temporally coincident with the Lidar data? How much smaller was the accuracy?

Authors: After rereading this work (Johnson et al., 2020), it was not clear how the accuracy of the Lidar planialtimetric data was evaluated by Johson et al. (2020), especially the oldest (1998 - 2010). In this case, we have preferred to remove this sentence from the section “Remote sensing”.

Reviewer 2

LINE 136 analyses

Authors: Ok, thank you (line  154).

Reviewer 2

LINE 150 This is unclear. What “previously identified land cover” data set? What year, source etc?

Authors: QuickBird satellite images, downloaded from Google Earth Engine with a ground pixel resolution of 2.44 m (multispectral) and three bands (blue, green, red) (Gorelick et al., 2017), were acquired on Nov/2004, Oct/2005, Oct/2007, Sep/2008, Dec/2010, Nov/2012, Jan/2015, and March/2019 (lines 139-142). Drone images (resolution of 2.6 cm) permitted the identification of Avicennia trees in the marshes and the beach barrier. Drone images and fieldwork data provided a consistent indicator to support the classification derived from the Quickbird images (Table 1, supplementary material). Ground Control Points (GCPs, Fig. 1 and Table 1, supplementary material) reinforced the identification of each land cover type (black mangrove, marsh, and beach barrier) (lines 169-174).

Reviewer 2

LINE 168 Header is “D models”. Should this be 3D models?

Authors: Ok, thank you (line  201).

Reviewer 2

LINE 172-173 “A high resolution, dense point cloud was executed based on point clouds with point spacing between 3 and 5 cm” I do not understand. A dense point cloud was “executed” from point clouds? Or did you just merge the individual point clouds to create a point cloud that covered the AOI?

Authors: The Agisoft Metashape software constructed a set of points in 3D space from all matched pairs between aligned photos. Erroneous points in the sparse point cloud were removed to improve the model final geometry. This cleaned sparse point cloud was used as a reference to reconstruct a more detailed set of geometries known as the dense point cloud (Olson et al., 2013)  (line  203- 208).

Reviewer 2

LINE 173 How was the point cloud analyzed to remove vegetation? What algorithm is used?

Authors: This dense and accurate 3D point cloud with point spacing between 3 and 5 cm was manually classified. The contrasts of colors and elevations of point clouds enabled identification of points representing the vegetation cover and the sandy barrier surface. The points representing the sandy barrier surface were used to obtain a digital terrain model (DTM) (lines 208 – 213).

Reviewer 2

LINE 198 I do not understand “breaking the area and assessed into many small squares”. Do you mean dividing the study area into a grid? If so, is this a uniform grid (uniform X and Y) or non-uniform grid?

Authors: Cut-and-fill volumes were calculated within a selected area using Global Mapper software version 18. Volumetric calculations were performed by dividing the area of interest up in to small rectangular pieces following a uniform grid and then calculating the sum volume of the small 3D rectangles (Volume = Height * Pixel Size) between terrain models and the cut surface (“Global Mapper User’s Manual,” 2020) (lines: 237 – 240).

Reviewer 2

LINE 201 These Zones are not indicated on Figure 1b. There is indication in Fig 5. This needs to be clarified.

Authors: The fences and zones are indicated in figures 1c and 6c (lines 242 – 243).

Reviewer 2

LINE 209 This could be explained more clearly using “cross shore” and “longshore” I think. You have nine vertical profiles. Seven profiles are cross-shore transects that start landward of the dune ridge and end at the shoreline (perpendicular to the shoreline). Two longshore profiles follow the dune ridge line (generally parallel to the shoreline).

Authors: Ok, thanks. “Seven profiles are cross-shore transects that start landward of the dune ridge and end at the shoreline (perpendicular to the shoreline)” (lines 249 – 251). “One longshore profile follows the top of the dune ridge line (parallel to the shoreline) of the year of each digital terrain model” (lines 253 – 254).

Reviewer 2

LINE 220 How are you identifying the upper limit of the intertidal zone? Did you digitize from the imagery using a wet-dry line? Clarify.

Authors: Yes, the upper limit of the intertidal zone, evidenced by a wet-dry line in the images, was used as a reference to evaluate the shoreline dynamics (lines 182 – 183).

Reviewer 2

Table 1 misspelling “data”. It says Dada. What is Mangr? Mangrove?

Authors: Tables 1 and 2 were modified according to the suggestions.

Reviewer 2

OVERALL METHODS COMMENT: The methods section is very confusing and disjunct. A table or figure of the different data source and processing steps would help clarify how each remote sensing and other data (Quickbird, drone, lidar, GCPs, etc) is used generate the planialtimetric, (vegetation?), meteorological and oceanographic time series data.

Authors: We have added a Methodology flow chart (Fig. 2) to evidence the sequence of activities and data processing (lines 96 – 101).

 

Reviewer 2

Perhaps reordering the methods to match the Results would also help. You end the methods with the oceanographic and fluvial data, but begin the Results with these data.

Authors: The Section Methods was restructured (2.1. Study area, 2.2. Historical oceanographic data, 2.3. Remote sensing, 2.4 Image classification, 2.5. Analyses of spatial data, and 2.6. 3D models ), and part of the text was rewritten (lines 96 – 101,  160 – 164, 169 – 174, 183 – 184, 205 – 208, 212 – 213, 219 - 227, 235 -238, 245 – 253).

 

Reviewer 2

Also, you have two a’ to b’ transects. I recommend reconsidering these labels so they are different. Is there a reason why A-B transect is different than a’ – b’ transect?

Authors: The transect labels were sequenced so that they are more easily individualized in their respective figures (Fig. 1 a’–b’; Fig. 3 c’-d’, e’-f’, g’-h’, i’-j’; Fig. 5 k’-l’, Fig. 6 m’-n’; Fig. 7 o’-p’) (lines 251 – 256).

Reviewer 2

It is important to indicate why these transects were chosen (random or intentional?) for each analyses and why they are different locations.

Authors: The locations chosen for each cross-shore transect have a wide spatial representation of the intertidal and supratidal zones of the studied coast. One longshore profile follows the top of the dune ridge line (parallel to the shoreline) of the year of each digital terrain model (lines 250 – 252).

Reviewer 2

Perhaps putting them on one map and calling them “vertical profile transects” and “planimetric transects” (or something) and also making it clear in the methods text that the cross-shore profiles are used for sediment volumes and planimetric for measuring shoreline and habitat changes would be helpful.

Authors: The designation of “planialtimetric profile transects” and “planimetric transects” were followed along the text and figure legends (lines 187 – 188, 249 – 250, 304 – 307, 311 – 312, 346 – 347, 351-352). Planialtimetric cross-shore profiles were used for sediment volume analysis, while planimetric cross-shore transects for measuring shoreline and habitat changes (lines 254 – 256).

Reviewer 2

Fig. 2 The figure description requires more clarity. C) says these are profiles between 1998 and 2019, but only the top two have 1998 profile data. Clarify.

Authors: The figure 3 (old figure 2) description has been rewritten (lines 303 – 307).

Reviewer 2

GENERAL RESULTS COMMENT: Many of the values do not have error values, yet the vertical and horizontal accuracy is explicit in the methods. An indication of confidence or error on these measurements would improve these results.

Authors:  Margins of error were highlighted in the Section methods and in the figure/table captions (lines 186 – 187, 223 – 231, 274 – 275, 311 – 312,  314 – 315, 346 – 347, 353 – 354, 377).  Considering that the margins of error are between the first and fourth decimal place, we do not think it is appropriate to add the margin of error to each value presented in the text.

Reviewer 2

LINE 334-335 “This process caused a loss of ~15.6 ha of wetlands (14.52 ha of saltmarsh and 1.08 ha of mangrove) along 335 the 4-km coastline between 2004 and 2012” This is a discussion statement, not results. Reword to say “This process (sand accumulation) was coincident with a loss of wetlands…” Then you can make this assessment in the Discussion (that the sand accumulation might have caused the loss in wetlands and why this might be so).

Authors: Ok, thanks (lines 366-368, 482 – 490).

Reviewer 2

Table 2 is really hard to read and compare numbers. Suggest reorganizing to indicate the time interval in the Table description… ie. “Size of mangrove, saltmarsh and sandy flat areas before (2004 – 2012) and after (2012-2019) the beach nourishment project. Then make the table columns Geomorphological Units, Before, After, with subheadings for Gain/Loss. For example,

	Before renourishment		After renourishment
Geomorphological Unit	Gain (ha)	Loss (ha)	Gain (ha)	Loss (ha)
Mangrove
Marsh
Sandy flat

You might also have a column with the overall ratio (before:after).

 

Authors: Tables 1 and 2 were modified according to the suggestions. This suggestion greatly improved data presentation. Thanks.

Reviewer 2

Also note that there is probably too many numbers after the decimal point (would you say your precision is that accurate?).

Authors:  The numbers have been rounded to the first decimal point (table 2).

Reviewer 2

Also, you don’t mention “sandy flats” in the text, I assume you mean the sandy intertidal flat? If so, be consistent with naming, or indicate that you will use both terms “sandy intertidal flat (sandy flat)” or something like that.

Authors:  We replaced “sandy flat” with “sandy intertidal flat” in the Table 2.

Reviewer 2

LINES 363 – 369. This paragraph reads like Results, not discussion.

Authors: This sentence was moved to the Results (lines 291 – 294).

Reviewer 2

LINE 389-390 “Despite the beach nourishment project's effort to stabilize the beach barrier, the Quickbird images, recorded between Jan/2015 and Mar/2019, revealed shoreline retreat in the transects A and B and stability in transects C and D” So, 50% of your transects showed shoreline stabilization. This indicates the renourishment might have been partially successful? But it sounds like you are saying it was not. Explain or clarify.

Authors: Yes, our data indicate that the renourishment might have partially stabilized the beach barrier (lines 423 – 424), because within a few years after the beach nourishment project, the action of waves and currents, intensified by continuing RSL rise, continued to erode the sea-facing coastal barriers, as recorded between Oct/2017 and Nov/2019 (lines 513 - 526).

Reviewer 2

LINE 391 At this point, just use the zone feature name (supratidal and sandy intertidal flat) since your discussion is focused on the effect on habitats and not arbitrary zones.

Authors: Ok (line 421).

Reviewer 2

LINE 433-435 Citation?

Authors: Ok, thanks (line 461). Citations have been revised throughout the text.

Reviewer 2

OVERALL DISCUSSION: It is clear from photos/figures that sand fencing was installed, likely to encourage dune growth. You note that dune height increased after renourishment, but when were these sand fences established? Could the sand fences also be the cause of the dune growth (not just the renourishment)? Or were they also present prior to the renourishment? Please add to you discussion (and you might also put this info in the background).

Authors: Sand fencing was installed in 2013 along the dunes to control the location and rate of aeolian erosion or sand deposition (Consultants, 2015; Li and Sherman, 2015) (Lines 77 – 80, 439 - 441). The shoreline advance and volume gain phase might be attributed to the artificial input of sand to the beach barrier, installation of fences along the dune crests and establishment of backbarrier wetlands (lines 339 – 341, 414 – 416).

Reviewer 2

I also noted that some of the marsh grasses look evenly spaced, so if vegetation plantings occurred, that is also important to note.

Authors: Dune vegetation (Panicum amarum and Uniola paniculata) was planted in some sectors of the supratidal zone in 2016 (“Caminada Headland Beach and Dune Restoration,” 2015; Coastal Protection and Restoration Authority (CPRA)., 2021; Louisiana Coastal Wetlands Conservation and Restoration Task Force, 2016) (lines 78 – 80).

 

We hope to have addressed all comments accordingly. We look forward to having your positive evaluation and acceptance of the revised manuscript.

 

Best regards,

Marcelo Cohen

Federal University of Pará

Rua Augusto Corrêa, 01

Cep: 66075-110, Bairro: Guamá

Belém-Pará

Tel: 91-3201-7478

Cel: 91-8031-1300

E-mail: [email protected]

www.ufpa.br/cpgg

 

References

Caminada Headland Beach and Dune Restoration [WWW Document], 2015. URL https://res.us/projects/caminada-headland-beach-and-dune-restoration/ (accessed 6.15.21).

Coastal Protection and Restoration Authority (CPRA)., 2021. Barrier Island Status Report: Draft Fiscal Year 2022 Annual Plan. Coastal Protection and Restoration Authority of Louisiana (CPRA). Baton Rouge, LA.

Cohen, M.C.L., Behling, H., Lara, R.J., Smith, C.B., Matos, H.R.S., Vedel, V., 2009. Impact of sea-level and climatic changes on the Amazon coastal wetlands during the late Holocene. Veg. Hist. Archaeobot. 18, 425–439. https://doi.org/10.1007/s00334-008-0208-0

Cohen, M.C.L., de Souza, A. V., Rossetti, D.F., Pessenda, L.C.R., França, M.C., 2018. Decadal-scale dynamics of an Amazonian mangrove caused by climate and sea level changes: inferences from spatial-temporal analysis and Digital Elevation Models. Earth Surf. Process. Landforms 43, 2876–2888. https://doi.org/10.1002/esp.4440

Cohen, M.C.L., Lara, R.J., 2003. Temporal changes of mangrove vegetation boundaries in Amazonia: Application of GIS and remote sensing techniques. Wetl. Ecol. Manag. 11, 223–231. https://doi.org/10.1023/A:1025007331075

Consultants, C.E., 2015. Caminada Headland Beach and Dune Restoration (BA-45) Completion Report; Coastal Protection and Restoration Authority: Baton Rouge, LA, USA.

Global Mapper User’s Manual [WWW Document], 2020. URL http://www.globalmapper.it/helpv11/Help_Main.html (accessed 4.1.20).

Gorelick, N., Hancher, M., Dixon, M., Ilyushchenko, S., Thau, D., Moore, R., 2017. Google Earth Engine: Planetary-scale geospatial analysis for everyone. Remote Sens. Environ. 202, 18–27. https://doi.org/10.1016/j.rse.2017.06.031

Johnson, C.L., Chen, Q., Ozdemir, C.E., 2020. Lidar time-series analysis of a rapidly transgressing low-lying mainland barrier (Caminada Headlands, Louisiana, USA). Geomorphology 352, 106979. https://doi.org/10.1016/j.geomorph.2019.106979

Li, B., Sherman, D.J., 2015. Aerodynamics and morphodynamics of sand fences: A review. Aeolian Res. https://doi.org/10.1016/j.aeolia.2014.11.005

Louisiana Coastal Wetlands Conservation and Restoration Task Force, 2016. Caminada Headlands Back Barrier Marsh Creation (BA-171) [WWW Document]. URL https://mississippiriverdelta.org//files/2017/03/CWPPRA-Caminada-headlands-back-barrier-marsh-restoration.pdf (accessed 6.15.21).

Olson, B.R., Placchetti, R.A., Quartermaine, J., Killebrew, A.E., 2013. The Tel Akko total archaeology project (Akko, Israel): Assessing the suitability of multi-scale 3d field recording in archaeology. J. F. Archaeol. 38, 244–262. https://doi.org/10.1179/0093469013Z.00000000056

 

Reviewer 3 Report

The research design of the study is appropriate and the materials and methods are described in detail. The images clearly explain the used methods. The article can be published without further revision.

Author Response

Dear Reviewer 3

We are grateful for the positive evaluation and acceptance of this manuscript.

 

Marcelo Cohen

Federal University of Pará

Rua Augusto Corrêa, 01

Cep: 66075-110, Bairro: Guamá

Belém-Pará

Tel: 91-3201-7478

Cel: 91-8031-1300

E-mail: [email protected]

www.ufpa.br/cpgg

 

Round 2

Reviewer 1 Report

Dear Editor,

The authors have revised the Paper to meet the main requests for change and the suggestions I recommended. 

I feel that the review process led to an improved manuscript, and I suggest the acceptance of the paper for publication in Remote Sensing. 

Sincerely Yours, 

Reviewer 2 Report

The authors have done a thorough job of addressing my comments on their first draft and I recommend publication in its present form.