Frequency and magnitude of debris flows on Cheekye River, British Columbia

Jakob, Matthias; Friele, Pierre A.

doi:10.1016/j.geomorph.2009.08.013

Cited by 78 publications

(46 citation statements)

References 25 publications

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“…Identification of common debris-flow sizes and transport characteristics in the transit zone are of paramount importance for the design of torrent control, a realistic assessment of volumes deposited, or the delineation of hazard zones. While this study emphasizes that a coupling of tree-ring records with field surveys can be used to draw a very detailed envelope for the debris-flow activity of the recent past and allows for climate control, data clearly lack higher predictive power for the identification of rare and very rare events with return periods of 10 3 or 10 4 years, such as recently illustrated by Jakob and Friele (2010). Another possible limitation of the approach lies in the fact that (i) more recent events may overprint or erode evidence of former activity; (ii) small events may stall inside the channel without leaving deposits on the cone, and that (iii) the rare, but large events of 1922, 1948, and 1993 may have reset the debris-flow system.…”

Section: Discussionmentioning

confidence: 95%

Magnitude–frequency relationships of debris flows — A case study based on field surveys and tree-ring records

Stoffel

2010

Geomorphology

154

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Section: Discussionmentioning

confidence: 95%

Magnitude–frequency relationships of debris flows — A case study based on field surveys and tree-ring records

Stoffel

2010

Geomorphology

154

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“…Accordingly, the risk has increased dramatically and once debris flows occurred, the consequence is usually disastrous. So, it is worth noting that the areas susceptible to debris flows and related flooding with low frequency but large magnitude should be assessed scientifically (Wang 2005;Jakob and Friele 2010) and the hazard regions should be zoned exactly. What is more, comprehensive measures including both engineering measures and also non-engineering measures should be adopted for risk management and hazard mitigation.…”

Section: Depositional Characteristics and River Blockingmentioning

confidence: 99%

Catastrophic debris flows triggered by a 4 July 2013 rainfall in Shimian, SW China: formation mechanism, disaster characteristics and the lessons learned

Zheng

Song

et al. 2014

Landslides

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Catastrophic debris flows triggered by a 4 July 2013 rainfall in Shimian, SW China: formation mechanism, disaster characteristics and the lessons learned Abstract On 4 July 2013, three catastrophic debris flows occurred in the Hougou, Majingzi, and Xiongjia gullies in Shimian county and produced debris dams and river blockages, resulting in serious casualties and huge economic loss. Though debris flows have been identified prior to the catastrophic events, their magnitudes and destructive power were far beyond early recognition and hazard assessment. Our primary objective for this study was to explore the formation mechanism and typical characteristics and to summarize the lessons learned from these disastrous events in order to avoid the repeat of such disasters in the future. Based on field investigation and imagery interpretation of remote sensing carried out following the catastrophic events, four conclusions were drawn: (1) The catastrophic debris flows were initiated from surface-water runoff, and the triggering factor was attributed to the local intensive rainfall with an hourly intensity of more than 46.7mm. (2) Entrainment was the most important sedimentsupplying method for the debris flow occurrence, and the source materials transported by debris flows from the three gullies were estimated to be about 97×10 4 m 3 in volume altogether. (3) As surface-water runoff eroded and entrained hillslope and channel materials persistently, debris flows were characterized by intensive incision at upper or middle reaches and significant magnification effect in flow discharge and volume downstream. Corresponding peak discharge surveyed at the outlets of the Hougou, Majingzi, and Xiongjia gullies was estimated up to 751.0m 3 /s, 870.1m 3 /s, and 758.7m 3 /s, respectively. (4) Debris flows that occurred from the three gullies all belonged to viscous ones and the bulk densities were calculated more than 1.80g/cm 3 , indicating a huge carrying capacity and destructive impacting power. In addition, the lessons learned from the catastrophic events were summarized, including recognition and assessment on debris flow hazard and utilization of deposition fan. In this paper, prevention suggestions on debris flow prone valleys with high-vegetation coverage and low occurrence frequency were also put forward. The results of this study contribute to a better understanding on the initiation mechanism, dynamic characteristics, and disaster mitigation of debris flows initiated from intense rainfall and surface-water runoff in mountainous areas.

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“…This approach, integral risk management, requires fundamental knowledge of the expected natural hazardous processes, and their spatial extent and intensities. The estimation of flow parameters like discharge, flow velocity or flow height are considered to be essential (Guzzetti 2000;Lin et al 2002;Glade and Crozier 2005;Fuchs et al 2008;Jakob and Friele 2010). Estimates of debris-flow characteristics are often based on post-event field investigations, and may be related to a certain cross section in the channelized transit zone of a torrent channel.…”

Section: Introductionmentioning

confidence: 99%

Debris-flow velocities and superelevation in a curved laboratory channel

2015

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Abstract:The vortex equation is often used to estimate the front velocity of debris flows using the lateral slope of the flow surface through a channel bend of a given radius. Here we report on laboratory experiments evaluating the application of the vortex equation to channelized debris flows. Systematic laboratory experiments were conducted in a 8 m long laboratory flume with a roughened bed, semi-circular cross section (top width 17 cm), and two different bend radii (1.0 and 1.5 m) with a common bend angle of 60°, and two channel inclinations (15°and 20°). Four sediment mixtures were used with systematic variations in the amount of fine sediment. In the experiments, 12 kg of water-saturated debris were released in a dam-break fashion, and multiple experiments were conducted to verify the repeatability for a given sediment mixture. Data are available for 69 experimental releases at a channel inclination of 20°and 16 releases at an inclination of 15°. Flow velocity was determined with high-speed video, and flow depth and the lateral inclination of the flow surface (superelevation) were measured using laser sensors. In general, the results from an individual sediment mixture are repeatable. We found that the channel slope as well as centerline radius have a significant influence on the correction factor k used in the vortex equation. Relatively coarse-grained sediment mixtures have larger superelevation angles than finer-grained mixtures. We found a statistically significant relation between the correction factor and Froude number. Correction factors of 1 < k < 5 were found for supercritical flow conditions. However, for subcritical flow conditions the correction factor shows a larger value as a function of the Froude number, which leads to an adaption of the forced vortex formula considering active and passive earth pressures. Finally, based on our experimental results, we present a forced vortex equation for debris-flow velocity estimation without a correction factor. Mots-clés : coulée de débris, vitesse de front de coulée, inclinaison latérale, modèle physique, équation de vortex force.

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Frequency and magnitude of debris flows on Cheekye River, British Columbia

Cited by 78 publications

References 25 publications

Magnitude–frequency relationships of debris flows — A case study based on field surveys and tree-ring records

Magnitude–frequency relationships of debris flows — A case study based on field surveys and tree-ring records

Catastrophic debris flows triggered by a 4 July 2013 rainfall in Shimian, SW China: formation mechanism, disaster characteristics and the lessons learned

Debris-flow velocities and superelevation in a curved laboratory channel

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