Complex internal architecture of a debris‐flow deposit revealed using ground‐penetrating radar, <scp>C</scp>ass, <scp>N</scp>ew <scp>Z</scp>ealand

Starheim, Colette C. A.; Gomez, Christopher; Harrison, Justin; Kain, Claire; Brewer, Nicholas J.; Owen, Kirsty; Hadmoko, Danang Sri; Purdie, Heather; Zawar-Reza, Peyman; Owens, I. F.; Wassmer, Patrick; Lavigne, Franck

doi:10.1111/nzg.12002

Cited by 6 publications

(6 citation statements)

References 29 publications

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“…However, in comparison with other studies of GPR in debris-flows, such complex forms have never been detected, and one should be cautious with this interpretation. Indeed, in New Zealand, Starheim et al [9] imaged a debris-flow deposit using Ground Penetrating Radar. The debris-flow was in its simplest form, i.e.…”

Section: Discussionmentioning

confidence: 99%

Local Morphology and Internal Architecture of the Kawajiricho 2018 Debris-flow Deposit (Hiroshima, Japan)

Gomez¹,

Imai²,

Setiawan³

et al. 2022

Preprint

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Debris-flows are recurrent events on mountain- and hill- slopes, and they have been the object of numerous field investigations and sampling, however most of this work reposes on imagery and outcrop analysis, in such a way that there are still only a handful of studies investigating the internal architecture of these events’ deposits. In the present contribution, we aims at underneath the internal structure of a portion of a debris-flow deposit that was accessible in the aftermath of the 2018 heavy-rainfall debris-flows in Hiroshima Japan. Using a Ramac Pro-Ex GPR with 500 MHz and 800 MHz antenna, a set of longitudinal and transversal transects was used to characterize the deposit. The results demonstrated that a set of subhorizontal layers have filled the valley, and interacting with local terrace edges, these layers have piled up and overcome the obstacle. Across the valleys, a set of trough suggest the presence of channels that were also filled during the event. Finally, in the channel post-event, a set of radargram “cross-bedded units” shows that the final deposition in the channel was of a more dilute flow, typical of a Newtonian flow. This set of units was not to be found at the surface of the post-event pseudo-surface, suggesting that the flow ended as a debris-flow on this surface, and that it is only when the flow dug the final channel that the nature of the flow returned from debris-flow to Newtonian flow.

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Section: Discussionmentioning

confidence: 99%

Local Morphology and Internal Architecture of the Kawajiricho 2018 Debris-flow Deposit (Hiroshima, Japan)

Gomez¹,

Imai²,

Setiawan³

et al. 2022

Preprint

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“…The loose debris was originally from easily-weathered slate, dolomite, and phyllite with a density corresponding to 2.65 t/m 3 . In addition, it is to be emphasized that the way that coarse and fine particles appeared in the vertical profile within loose debris was also considered on the basis of three vertical depositing patterns (i.e., normal, mixed, and inverse grading) reported in the earlier studies [36][37][38][39][40][41]. However, these findings of the vertical grading patterns were generally restricted to the post-event analysis and alluvial deposits.…”

Section: Factor Selectionmentioning

confidence: 99%

“…Specifically, coarse particles placed at the bottom layer and fine sediment on the top layer (Case E1, see Figure 2a), the coarse particles distributed on the top layer with fine grains at the bottom layer (Case E3, see Figure 2b), and both the coarse and fine particles fully mixed and covering the whole vertical profile (Case E2, see Figure 2c). In order to quantify this, a vertical grading coefficient ψ was proposed and written as In addition, it is to be emphasized that the way that coarse and fine particles appeared in the vertical profile within loose debris was also considered on the basis of three vertical depositing patterns (i.e., normal, mixed, and inverse grading) reported in the earlier studies [36][37][38][39][40][41]. However, these findings of the vertical grading patterns were generally restricted to the post-event analysis and alluvial deposits.…”

mentioning

confidence: 99%

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Shu

Wang

et al. 2017

Water

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Non-homogeneous debris flows generally occur during the rainy seasons in Southwest China, and have received considerable attention in the literature. Regarding the complexity in debris flow dynamics, experimental approaches have proven to be effective in revealing the formative mechanism for debris flow, and quantifying the relations between the various influencing factors with debris-flow formation and subsequent transport processes. Therefore, a flume-based and experimental study was performed at the Debris Flow Observation and Research Station of Jiangjia Gully in Yunnan Province, to theoretically analyze favorable conditions for debris-flow formation and initial transport by selecting the median particle size d 50 , flow rate Q, vertical grading coefficient ψ, slopes S, and the initial soil water contents W as the five variables for investigation. To achieve this, an optimal combination of these variables was made through an orthogonal experimental design to determine their relative importance upon the occurrence and initial mobilization behavior of a debris flow and to further enhance our insight into debris-flow triggering and transport mechanisms.

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“…From this accident, researchers started to develop GPR to image the ice thickness, characteristics [17] as well as the ice and snow levels and density [18], before turning to soils and river environments: deposits architecture and related processes [19], floodplain structure [20], and faults through the floodplains [21], landslides' displacements [22], etc. GPR work also extended on the coastlines [23], as well as more challenging environment in term of data acquisition and processing, such as debris-flow deposits [24] and still-warm (600 degrees) pyroclastic flow deposits [25]. Outside of the field of geosciences, high-frequency antenna have been also instrumental when hatched to a truck to monitor highways' pavement [26], bridge structures, and tunnels [27], etc.…”

Section: Introductionmentioning

confidence: 99%

Detection and Velocimetry of Floating Wood for Flood Disaster Risk Management Using Electromagnetic Imaging

Gomez

Hotta

Miyata

et al. 2023

A New Conference Journal, Proceedings

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Wood travelling in river is a major hazard to lives and infrastructures, because tons of wood material can travel nearing the speed of the flood-flow. If post-event mapping, detection and numerical simulation have made important progress, detecting in-flow driftwood in all weather and at all-time still presents several challenges. The present work aims to expand the capacity to detect in-flow wood by adapting the Ground Penetrating Radar electromagnetic method. The laboratory test was carried over a water circulation flume using an 800 MHz nominal frequency antenna sampling at 100 Hz and a video-camera set on top of the flume to measure the average velocity of the wood logs. A set of single wood logs of 20 cm length travelled underneath the antenna. The GPR results have demonstrated that the method had the potential to detect moving wood, and that it could "see" underneath the water to the shallow flume floor. The experiments resulted in the ability to count wood travelling underneath the antenna, and instantaneous velocity were obtained with velocities ranging from 0.307 to 0.352 m/s, which slightly higher than the averaged velocity measured from video-imaging. This difference is explained by in-flow acceleration of the wood after its introduction in the flume.

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Complex internal architecture of a debris‐flow deposit revealed using ground‐penetrating radar, Cass, New Zealand

Abstract: International audienc

Cited by 6 publications

References 29 publications

Local Morphology and Internal Architecture of the Kawajiricho 2018 Debris-flow Deposit (Hiroshima, Japan)

Local Morphology and Internal Architecture of the Kawajiricho 2018 Debris-flow Deposit (Hiroshima, Japan)

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Detection and Velocimetry of Floating Wood for Flood Disaster Risk Management Using Electromagnetic Imaging

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