Local-scale post-event assessments with GPS and UAV-based quick-response surveys: a pilot case  from the Emilia–Romagna (Italy) coast

Duo, Enrico; Trembanis, Arthur Chris; Dohner, Stephanie; Grottoli, Edoardo; Ciavola, Paolo

doi:https://doi.org/10.5194/nhess-18-2969-2018

Articles | Volume 18, issue 11

https://doi.org/10.5194/nhess-18-2969-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

The use of remotely piloted aircraft systems (RPAS) in monitoring...

https://doi.org/10.5194/nhess-18-2969-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 11

Research article

|

12 Nov 2018

Research article |

| 12 Nov 2018

Local-scale post-event assessments with GPS and UAV-based quick-response surveys: a pilot case from the Emilia–Romagna (Italy) coast

Enrico Duo, Arthur Chris Trembanis, Stephanie Dohner, Edoardo Grottoli, and Paolo Ciavola

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Final revised paper (published on 12 Nov 2018)
Preprint (discussion started on 10 Oct 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Response to Quick Response Assessment of the Impact of an Extreme Storm Combining Aerial Drone and RTK GPS by Trembanis et al.', Anonymous Referee #1, 20 Oct 2017
- AC3: 'Final Author Review Comments', Arthur Trembanis, 05 Jan 2018
RC2: 'NHESS-2017-337 Referee Comment from Anonymous Referee #2', Anonymous Referee #2, 15 Nov 2017
- AC2: 'Final Author Review Comments', Arthur Trembanis, 05 Jan 2018
SC1: 'Author's answer to referees #1 and #2 - Proposed changes - General overview', Enrico Duo, 06 Dec 2017
- AC1: 'Author Final Comments', Arthur Trembanis, 30 Dec 2017

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (01 May 2018) by Paolo Tarolli

AR by Enrico Duo on behalf of the Authors (08 Jun 2018)

ED: Referee Nomination & Report Request started (19 Jun 2018) by Paolo Tarolli

RR by Anonymous Referee #1 (10 Jul 2018)

Suggestions for revision or reasons for rejection

The present manuscript presents a post-event assessment of the morphological changes of a strip of a beach in Emilia-Romagna following an intense storm. The study dominantly relies on UAV techniques to i) map the extent of floodlines and ii) create DSMs to evaluate volume changes compared to a baseline. Some RTK–GPS transects are presented and used to validate UAV datasets. These outcomes are coupled with interviews with stakeholders, and the authors formulate a possible protocol to be implemented during future crises. The present manuscript is a great improvement compared to the initial submission.

My main concern remains the scope of the paper, as the title has been changed and now suggests that it tackles a general framework to integrate quick–response post–event studies with regional frameworks. This does not appears to be the case. The present manuscript presents an interesting application to one case study with obvious potential applications for other crises, but does not provide any attempt to integrate it into a wider framework. Some insights of the regional framework are given in Section 2 and outcomes of the present study are somehow compared with the regional study in Section 5 (see detailed comments), but the main results are still related to the one case study. I suggest modifying the title accordingly and strengthen the possible integration in the discussion section. Please understand that this comment does not reduce the value of the present study!

As a result, I feel that the paper deserves to be published once the main scope is clearly defined as the study of one pilot case study, based on which more general applications can be identified and discussed appropriately. Please find below some general comments as well as an annotated pdf file.

Specific comments
• Section 5 should be divided in sub–headers to guide the reader through the discussion
• A fair amount of time is dedicated to convince the reader that UAVs are superior to RTK–GPS and LiDAR strategies for the present application. However, the majority of the presented study relies on the use of the UAV orthomosaic image, which can only be obtained with a UAV. Isn’t that a sufficient proof that UAVs are more appropriate for this kind of studies?
• The comparison between the results of this study with the regional study in Section 5 must be clarified and more details of the method of Perini et al. (2015b, 2016) must be provided to the reader. In this state, this part of the discussion lacks transparency.

Other points
• Care is required with the use of acronyms. In several occurrences, they are defined several times.
• There are a number of words (and sometime sentences) that are rather vague and unconstrained.
See annotated pdf.
• Consistency is needed with the use of UAVs, which is still sometime called “drone” in the text.
• I would really require a native English speaker to carefully proof–read the manuscript, as the language is sometime a barrier to understanding some long sentences.

Best regards

Referee Report: PDF

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RR by Anonymous Referee #3 (03 Aug 2018)

Suggestions for revision or reasons for rejection

The paper describes the use of GPS RTK and UAV for the identification of effects caused by storms on beaches.
The paper presents, in particular, the case study of the Saint Agatha storm and their effect on a portion of coast between Porto Garibaldi and Lido di Spina.
The paper is well organized and provides a detailed description of the case study.
One of the limitations of the acquired dataset is the resolution of the Phantom II and the manual acquisition of images sequence. This limitation is pointed out by authors in the discussion and is the reason because they acquired 50 ground control points and used only 14.
The identification of floodmark is an interesting approach that improves the methodology. The approach used for the acquisition of these points is straightforward and effective, but I would like to suggest that other possibilities based on the use of stricture from motion and oblique cameras acquisition are possible. An example of this approach can be found in the following paper: Giordan, D., Notti, D., Villa, A., Zucca, F., Calò, F., Pepe, A., Dutto, F., Pari, P., Baldo, M., and Allasia, P.: Low cost, multiscale and multi-sensor application for flooded area mapping, Nat. Hazards Earth Syst. Sci., 18, 1493-1516, https://doi.org/10.5194/nhess-18-1493-2018, 2018.
An important limitation of the submitted manuscript that should be improved is the definition of a possible methodology for the use of GPS RTK and UAV for the identification of areas damaged by storms. I would like to point out that the title of the paper is: “Integrating regional protocols for post-event assessments with local GPS and UAV-based quick response surveys: a pilot case from the Emilia-Romagna (Italy) coast”.
I think that readers want to find in this paper a detailed description of the protocol, which is still missing.
I think that authors should add to the discussion a table with some important elements that can be used to define this protocol. Some examples: i) which is the minimum GSD required? ii) how many ground control points are required and which could be the geometry of the distribution of GCPs? iii) the overlap of images. If you consider the tutorial of Photoscan, the suggestion is 75-80% of overlap for san and snow.
Only with a better definition of the methodology introduced in the title, the article can be considered complete.

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ED: Reconsider after major revisions (further review by editor and referees) (09 Aug 2018) by Paolo Tarolli

AR by Enrico Duo on behalf of the Authors (19 Sep 2018) Author's response Manuscript

ED: Publish as is (14 Oct 2018) by Paolo Tarolli

AR by Enrico Duo on behalf of the Authors (15 Oct 2018)

Short summary

This study illustrates the implementation of a local-scale post-event survey that combined GPS and UAV-based techniques with qualitative information collected through interviews with local stakeholders. The comprehensive approach employed in this case study was conducted on the Emilia-Romagna coast (Italy), in the immediate aftermath of an extreme event that impacted the shoreline on the 5-6 February 2015, called the St Agatha storm.