Assessment of potential beach erosion risk and impact of coastal zone development: a case study on Bongpo–Cheonjin Beach

Lim, Changbin; Kim, Tae Kon; Lee, Sahong; Yeon, Yoon Jeong; Lee, Jung Lyul

doi:https://doi.org/10.5194/nhess-21-3827-2021

Articles | Volume 21, issue 12

https://doi.org/10.5194/nhess-21-3827-2021

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

https://doi.org/10.5194/nhess-21-3827-2021

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

Articles | Volume 21, issue 12

Research article

|

20 Dec 2021

Research article |

| 20 Dec 2021

Assessment of potential beach erosion risk and impact of coastal zone development: a case study on Bongpo–Cheonjin Beach

Changbin Lim, Tae Kon Kim, Sahong Lee, Yoon Jeong Yeon, and Jung Lyul Lee

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Final revised paper (published on 20 Dec 2021)
Preprint (discussion started on 08 Jul 2021)

Interactive discussion

Status: closed

RC1:
'Comment on nhess-2021-180', Anonymous Referee #1, 26 Jul 2021

This MS aims to present a practical approach for quantitative assessment of beach erosion risk potential, induced by three common factors in coastal environments. These include reduction of sediment supply from updrift river, shoreline change due to construction of harbor breakwater, and erosion caused by high wave attack. The methodology outlined in the MS is rational and the analysis is supported by approximate formulae, empirical model and field data derived from arial photographs and beach survey for a case study at Bongpo-Cheonjin Beach in Korea. Overall, the content in this MS is well constructed and balanced with theory for quantitative assessment of beach erosion potential. It is therefore recommended for publication in the NHESS after minor revision, following, at least, the detailed suggestions listed under the original section and sub-section titles in part C in my Referee Report attached.

Citation: https://doi.org/10.5194/nhess-2021-180-RC1
- AC1:
  'Reply on RC1', Changbin Lim, 18 Aug 2021
  
  Thank you for your valuable comment of anonymous referee. We revised the manuscript with the detailed suggestions. Our detailed responses are described in the attached PDF file.
  
  Citation: https://doi.org/10.5194/nhess-2021-180-AC1
  - RC2: 'Reply on AC1', Anonymous Referee #1, 20 Aug 2021
    
    1. Reviewer has carefully read the reply from CB Lim in which the changes to their previous MS are described in detail.
    2. Reviewer is satisfied with the changes the authors have proposed and am happy to recommend
    this paper to be accepted for publication in NHESS,
    subject to one condition that the FINAL full paper can be read smoothly.
    
    Citation: https://doi.org/10.5194/nhess-2021-180-RC2
    
    AC2: 'Reply on RC2', Changbin Lim, 16 Sep 2021
    
    Thank you for those kind words. We will do our best to complete a good paper.
    
    Citation: https://doi.org/10.5194/nhess-2021-180-AC2
RC3:
'Comment on nhess-2021-180', Anonymous Referee #2, 23 Aug 2021

See attached comments

Citation: https://doi.org/10.5194/nhess-2021-180-RC3
- AC3: 'Reply on RC3', Changbin Lim, 16 Sep 2021
  
  We thank the anonymous referee #2 for their valuable comments. We have revised the manuscript with detailed suggestions. The paper has been revised in response to the comments of Reviewer #1. Detailed answers are explained in the attached PDF file.
  
  Citation: https://doi.org/10.5194/nhess-2021-180-AC3
RC4:
'Comment on nhess-2021-180', Anonymous Referee #1, 26 Aug 2021

Referee RC1 has read the detailed comments in nhess-2021-180-RC3-supplement (PDF) and agrees with all the issues raised in that supplement.
By combining the comments given by this referee (RRC1, Referee 1) and that of the RC3 (Referre 2?),
I belive the auhtors would be able to produc a good paper for many NHESS readers.

Citation: https://doi.org/10.5194/nhess-2021-180-RC4
- AC4: 'Reply on RC4', Changbin Lim, 16 Sep 2021
  
  By reflecting the opinions of the 1st and 2nd reviewers, we will be able to create a good paper for many NHESS readers. Responses to both reveiwers' comments can be found in AC3.
  
  Citation: https://doi.org/10.5194/nhess-2021-180-AC4

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (further review by editor and referees) (28 Sep 2021) by Daniele Giordan

AR by Changbin Lim on behalf of the Authors (29 Sep 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (08 Oct 2021) by Daniele Giordan

RR by Anonymous Referee #1 (14 Oct 2021)

RR by Anonymous Referee #2 (20 Oct 2021)

Suggestions for revision or reasons for rejection

Authors have satisfactorily addressed most of reviewers' comments and suggestions. However, I still have some suggestions/comments.

[1] There are some typographical and grammatical errors in the text. Please checl it.

[Lines 194 – 201] It is not clear how you pass from eq 7 to eq 8.
If by definition ΔQp = Qin – Qout
Then the right hand of eq (8) should be Qin – Qout – KV, which is not equal to the right hand of eq (7)

[Lines 257-261] Surveys taken 4 times per year during 8 years do not necessarily reflect the real importance of storm-induced erosion in the site, especially if you are interested in the impact of extreme events. This is clearly reflected in the fact that you will never rely on an extreme wave analysis done with just 8 years of data. Moreover, results obtained in New Zealand do not necessarily apply to your site, since they depend on specific wave conditions and beach morphology. Looking to your approach I would say than more than “shoreline retreat due to episodic storm” you are reflecting “shoreline seasonal fluctuations”.

[Section 2. PBEA due to development in watershed] Looking to fig 9, the Cheonjin river has its mouth out of the Bongpo-Cheonjin beach, so I would not expect too much influence on the beach (depending on the potential bypass of material from the beach at the north, just in the river mouth). However, this component should reflect not only the effects of river inputs but the net effect of all agents acting at this t-scale, i.e. river plus long-term cross-shore exchanges with the shoreface (provided your beach has no sediment losses/gains through both alongshore ends). Looking to your results, I would say that at the decadal scale, your beach can be considered (more or less) as in equilibrium.

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ED: Publish subject to minor revisions (review by editor) (28 Oct 2021) by Daniele Giordan

AR by Changbin Lim on behalf of the Authors (04 Nov 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (16 Nov 2021) by Daniele Giordan

AR by Changbin Lim on behalf of the Authors (21 Nov 2021) Manuscript

Short summary

This study aimed to quantitatively assess erosion risk. Methods for assessing each potential were proposed, and the corresponding erosion risk was calculated by introducing a combined potential erosion risk curve presenting the erosion consequence. In addition the method for verifying the risk was examined for the east coast of South Korea. We believe that our study makes a significant contribution to the literature and plays a key role in identifying methods that prevent erosion.