Watching the Beach Steadily Disappearing: The Evolution of Understanding of Retrogressive Breach Failures
Round 1
Reviewer 1 Report
Dear authors,
I've made some comments in the uploaded manuscript. Generally, I recommended some recasts, but the aim of the paper is clear and well discuss. Table 1 was cutted during the submission, therefore I didn't see its content.
Good luck
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
In the present paper the authors present a study regarding the ‘retrogressive breach failures’ (RBF events) often more loosely named ‘coastal flow slides’ or just ‘flow slides’. The authors have established that events, observed during the active phase, are characterized by a slow and steady retrogression into the shoreline, often continuing for many hours. This can be explained by the breaching mechanism, as elaborated in this paper. The mechanism has been observed in small-scale flume tests and in a large-scale field experiment.
In reviewer's opinion the topic of the paper is interesting, but the following issues must be clarified before considering the paper for a possible publication in the journal.
Originality and novelty of the paper. This issue is very important and must be clarified and well highlighted in the text. Advantages and limitations of the study respect to other ones existing in literature, in particular in the applications to real cases. Moreover, the authors could offer a broader view of their study in the context of the available literature on the topic. Paragraph 5 “Modern flow slide protection and coastal defense strategies” need to be expanded and discussed in more detailed with a better presentation and discussion of the model test and results obtained.
Minor corrections
For completeness a brief outline of the numerical techniques that could be used for the study of the aforementioned phenomena should be included in the text. For instance in the manuscript could be added a sentence like "Numerical modelling can be a powerful tool to study the RBF events. In this connection, for a better understanding of the failure mechanisms and run-out of landslides it is possible to use advanced numerical techniques as documented in literature (Crosta et al., 2003; Donga et al., 2017; Conte et al., 2019)”.
Crosta, G.B., Imposimato, S., Roddeman, D.G., 2003. Numerical modelling of large landslide stability and runout. Nat. Hazards Earth Syst. Sci. 3 (6), 523–538.
Donga Y., Wang D., Randolph M.F., 2017. Runout of submarine landslide simulated with material point method. Journal of Hydrodynamics 29 (3), 438–444. DOI: 10.1016/S1001-6058(16)60754-0.
Conte, E., Pugliese, L., Troncone, A., 2019. Post-failure stage simulation of a landslide using the material point method. Engineering Geology, Volume 253, 149-159. DOI: 10.1016/j.enggeo.2019.03.006
Moreover, the paper would certainly benefit from a proof read since there are minor errors.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript makes a case for discriminating between a slow, progressive beach failure and more rapid events attributed to liquefaction. This paper mostly describes historical and recent observation of these events, and does not approach the problem from a rigorous geotechnical or fluid mechanical viewpoint. The main goal of the manuscript seems to be to a) raise awareness of this phenomena and b) assign a name to it ("retrogressive breach failure"). This is maybe less technical than most papers submitted to JMSE, and the editors will have to decide whether it is appropriate. The presentation is readable, the images informative, and the references extensive.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The paper can be considered for publication in the present version.
