Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of the magnitude, return time, and conditioning factors of erosion and debris flow generation

Aguilar, Germán; Cabré, Albert; Fredes, Victor; Villela, Bruno

doi:https://doi.org/10.5194/nhess-20-1247-2020

Articles | Volume 20, issue 5

https://doi.org/10.5194/nhess-20-1247-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/nhess-20-1247-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 5

Research article

|

11 May 2020

Research article |

| 11 May 2020

Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of the magnitude, return time, and conditioning factors of erosion and debris flow generation

Germán Aguilar, Albert Cabré, Victor Fredes, and Bruno Villela

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Final revised paper (published on 11 May 2020)
Supplement to the final revised paper
Preprint (discussion started on 02 Aug 2019)
Supplement to the preprint

Interactive discussion

Status: closed

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

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RC1: 'Review of the manuscript "Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of magnitude, return time, and conditioning factors of erosion caused by debris flows"', Martin Mergili, 20 Aug 2019
- AC1: 'Reply from the authors to reviewer 1 “Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of magnitude, return time, and conditioning factors of erosion caused by debris flows”', german aguilar, 07 Oct 2019
- AC4: 'Reply from the authors to reviewer 1 “Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of magnitude, return time, and conditioning factors of erosion caused by debris flows”', german aguilar, 18 Nov 2019
RC2: 'Reviewer comments', Teresa Jordan, 11 Oct 2019
- AC2: 'Reply from the authors to reviewer 2', german aguilar, 31 Oct 2019
- AC5: 'Reply from the authors to reviewer 2', german aguilar, 18 Nov 2019
RC3: 'Comments on Aguilar et al paper', Juan Luis García, 25 Oct 2019
- AC3: 'Reply from the authors to reviewer 3', german aguilar, 31 Oct 2019
- AC6: 'Reply from the authors to reviewer 3', german aguilar, 18 Nov 2019

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (06 Dec 2019) by Paolo Tarolli

AR by german aguilar on behalf of the Authors (09 Dec 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Dec 2019) by Paolo Tarolli

RR by Martin Mergili (17 Dec 2019)

RR by Anonymous Referee #4 (05 Feb 2020)

Suggestions for revision or reasons for rejection

The paper considers the erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert.
The topic is fascinating but the lack of a rigorous scientific approach hampers the possibility that this manuscript can be considered suitable for the publication without radical improvements.
In the following some comments and suggestions:
Page 3 line 28: it is quite strange that the first cited figure in the manuscript is figure 9. Please, consider revising the order of figures.
Page 3 line 30: it is not clear what “this strategy” means; could be referred to the Terrestrial Cosmogenic Nuclides concentrations measurement but it is not clear, I suggest revising the organisation of this part of the chapter
Page 4 line 7: I am confident that the submitted paper Cabré et al. (submitted) will be published, but I suggest improving the description of the debris flow deposit to make this manuscript more detailed.
Chapter 2 general comment: the description of the study area is too limited. Readers are not able to know the extension of the area, the name of basins, and other necessary geomorphological information. This chapter should be thoroughly revised and partially rewritten.
Figure 1: ion this picture is presented a lot of information not cited in the text. I do not think that this is correct. Please, consider the possibility to add a chapter with the description of available data.
Chapter 3: this is the most important chapter of the manuscript, and it presents a lot of problems and limitations. First of all, readers are not able to understand exactly what the authors did. There a sequence of general information about methods and approach, but is not easy to understand what exactly was performed in this area. Did authors use the formula (1) or the ANOVA approach, or both? I suggest considering a workflow that describes better what authors exactly did.
Chapter 4.1: this is a general description that has already done by authors in the previous part of the manuscript.
Chapter 4.2: This is an important point of the manuscript. Volume estimations of debris flows are provided but in the chapter “method” there is not a real description of the accuracy of the presented method. Even in this chapter, volume estimations are presented without an explanation of the accuracy of the method and a definition of the tolerance of the evaluations. The definition of volumes expressed in meters without a range that describes the tolerance of the estimations is a big limitation of this paper.
Page 6 line 16: The sentence: “The propagation of errors entails an uncertainty of 10% for the volumes calculated with field measurements and 40% for volumes estimated by satellite image measurements” cannot be considered sufficient for the definition of uncertainty. A better description of the procedure adopted for the definition of these values should be provided by authors.

Page 7 line 5: the lack of description of the studied area has a strong impact in this chapter. Readers are not able to understand which (and how many) catchments produced debris flow and which are characterised by clean water flow.
Page 7 line 9: “Debris flows occurred only in 9% of the catchments” how many catchments are considered in this papers? I do not find a detailed description of this basic information.
Chapter 4.4: this chapter is very short, and the description of obtained results it is not very clear.
Page 8 line 19. “We propose based on field observations that this is because debris supply from rocky outcrops of hillslopes is not a significant source of sediments during the storms. Instead, we propose that the main source of debris flows is sediment stored in the drainage network.” This is a good point, but I am not sure that this comment is clearly supported by presented data.

Page 9: this page should be totally rewritten. It is not clear the real objective of this part of the manuscript. There is a critical mix between data of the studied basin and data of other basins studied by other authors and not related to the 2015 event. This data, in my opinion, should be presented earlier and the authors can make a discussion pointing out differences between the studied phenomenon and other case studies.

Page 10 line 1: the mean value of 1.3 mm of erosion has been calculated without an effective description of the accuracy of the method. The lack of a serious scientific method is very critical.
Page 10 line 3: “and the return time of these kind of events from paleoclimatic record of 1 event each 100 years.” I did not find in the manuscript this paleoclimatic study before this sentence.

Page 11 line 10 “The limitations to study erosion associated with an individual storm event include the lack of pre-event high resolution topography” in this paper, I do think that authors mentioned the availability of a detailed topography after the event.

Page 11 line 15: “Nevertheless, these records also underestimate the peak discharge associated with the storm because the gauging stations are commonly damaged by flash floods” Is this e general comment or referred to the presented case study?

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ED: Reconsider after major revisions (further review by editor and referees) (11 Feb 2020) by Paolo Tarolli

AR by german aguilar on behalf of the Authors (24 Mar 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (26 Mar 2020) by Paolo Tarolli

RR by Anonymous Referee #4 (02 Apr 2020)

ED: Publish as is (05 Apr 2020) by Paolo Tarolli

AR by german aguilar on behalf of the Authors (09 Apr 2020) Author's response Manuscript

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Short summary

We have calculated erosion caused by an extreme storm in the Atacama Desert. Erosion distribution depends on the ability of catchments to store sediments in stream networks between storms and generate debris flows during the storm. The order of magnitude of erosion is the same as the erosion rates calculated over the long term, so these storms have a relevant influence on the evolution of these arid fluvial systems.