Relationship between the accumulation of sediment storage and debris-flow characteristics in a debris-flow initiation zone, Ohya landslide body, Japan

Imaizumi, Fumitoshi; Hayakawa, Yuichi S.; Hotta, Norifumi; Tsunetaka, Haruka; Ohsaka, Okihiro; Tsuchiya, Satoshi

doi:https://doi.org/10.5194/nhess-17-1923-2017

Articles | Volume 17, issue 11

https://doi.org/10.5194/nhess-17-1923-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/nhess-17-1923-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 11

Research article

|

14 Nov 2017

Research article |

| 14 Nov 2017

Relationship between the accumulation of sediment storage and debris-flow characteristics in a debris-flow initiation zone, Ohya landslide body, Japan

Fumitoshi Imaizumi, Yuichi S. Hayakawa, Norifumi Hotta, Haruka Tsunetaka, Okihiro Ohsaka, and Satoshi Tsuchiya

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Final revised paper (published on 14 Nov 2017)
Preprint (discussion started on 16 Jan 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review', Carlo Gregoretti, 17 Feb 2017
- AC1: 'Reply for review comments', Fumitoshi Imaizumi, 10 Mar 2017
RC2: 'simple clarification', Carlo Gregoretti, 10 Mar 2017
- SC1: 'reply', Fumitoshi Imaizumi, 13 Mar 2017
  - RC3: 'specification', Carlo Gregoretti, 13 Mar 2017
    - SC2: 'reply', Fumitoshi Imaizumi, 14 Mar 2017
RC4: 'Review nhess-2017-20', Michel Jaboyedoff, 31 Mar 2017
- AC2: 'reply for comments', Fumitoshi Imaizumi, 20 Apr 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) (21 Apr 2017) by Paolo Tarolli

AR by Fumitoshi Imaizumi on behalf of the Authors (12 May 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 May 2017) by Paolo Tarolli

RR by Carlo Gregoretti (06 Jun 2017)

RR by Michel Jaboyedoff (03 Jul 2017)

RR by Anonymous Referee #3 (06 Jul 2017)

Suggestions for revision or reasons for rejection

The paper may reveal some valuable facts related to the initiation of debris flows in the upper stream. The long-term observation data are useful for understanding the initiation mechanism of debris flows. But the core findings are covered by too many trivial details. The authors use too many words to describe the background information. I think the manuscript could be accepted by the journal if major revisions are made, especially reducing some of unimportant content.

Specific Comments
1. I think the title is not appropriate, “Interactions between the accumulation of sediment storage and debris flow characteristics in a debris-flow initiation zone, Ohya landslide body, Japan”. The paper did not present the “interactions”. May be connections or relationship is better.

2. Page3 Line 6: “Similarly, shear stress needs to exceed shear strength at the bottom of a traveling sediment mass for the continuity of travel.”
Once the debris mass initiates, the shear stress need to keep it moving is equal to or even less than the shear strength sometimes. I think the sentence could be revised.
3. The angle is denoted with theta in figure 1a, but it is alpha in the text.
4. It is better if the images in figures such as Figure 3 have a scale.
5. 4.1 and 4.2 sections are too long. I think a brief description of the monitoring and TLS measuring can make readers focus on the topic.
6. Some discussions should be cautious. For example, Page 20 Line 21: “The proportional duration of partly saturated flow in the overall surges had a positive relationship with the volume of storage (Fig. 6). Thus, the volume of storage was a factor controlling not only the initiation of the debris flow, particularly in the supply limited basin (Bovis and Jakob, 1999; Jakob et al., 2005), but also the debris flow characteristics.”

I think the fact of “The proportional duration of partly saturated flow in the overall surges had a positive relationship with the volume of storage” cannot deduce the inevitable conclusion. I suggest “It indicates that” in place of “Thus”.

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ED: Reconsider after major revisions (further review by Editor and Referees) (17 Jul 2017) by Paolo Tarolli

AR by Fumitoshi Imaizumi on behalf of the Authors (28 Aug 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (29 Aug 2017) by Paolo Tarolli

RR by Carlo Gregoretti (11 Sep 2017)

ED: Publish subject to minor revisions (further review by Editor) (26 Sep 2017) by Paolo Tarolli

AR by Fumitoshi Imaizumi on behalf of the Authors (06 Oct 2017) Author's response Manuscript

ED: Publish as is (11 Oct 2017) by Paolo Tarolli

AR by Fumitoshi Imaizumi on behalf of the Authors (12 Oct 2017)

Short summary

Debris flow characteristics in the initiation zones are poorly understood because of the difficulty in monitoring. We studied the relationship between the flow characteristics and the accumulation conditions of the storage in an initiation zone of debris flow. Our study clarified that both partly and fully saturated flows are important processes in the initiation zones of debris flow. The predominant type of flow varied temporally and was affected by the volume of storage and rainfall patterns.