The importance of entrainment and bulking on debris flow runout modeling: examples from the Swiss Alps

Frank, Florian; McArdell, Brian W.; Huggel, Christian; Vieli, Andreas

doi:10.5194/nhess-15-2569-2015

Cited by 118 publications

(135 citation statements)

References 36 publications

(60 reference statements)

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“…Rockfall and snow avalanches, originating from the unstable and disintegrated gneisses in the Guttannen zone, frequently supply sediment from steep gullies to lower couloirs which span nearly the entire width of the steep rockwall below the Ritzlihorn (3263 m a.s.l.) Above this elevation, a rockslide was observed on 17 July 2009 from the unstable upper Ritzlihorn northeast wall (Figure 1(a)) (Tobler et al, 2014;Fölmli et al, 2015;Frank et al, 2015). Rockfall frequency considerably increases during springtime and is frequent from April to July (Geotest, 2010).…”

Section: Spreitgraben Catchmentmentioning

confidence: 97%

“…Debris-flow initiation was observed within days after the rockslide event. More than 600 000 m 3 of sediment were transported into the Hasliaare River between 2009 and 2011 (Tobler et al, 2014;Frank et al, 2015). The erosion and entrainment of this mixture continued into 2011 (Geotest, 2012).…”

Section: Spreitgraben Catchmentmentioning

confidence: 99%

“…Examples include rapid accumulation of sediment in the initiation zone (Evans et al, 2001;Rickenmann et al, 2001;Haeberli et al, 2002;Hauser, 2002;Hürlimann et al, 2003;Raymond et al, 2003;Huggel et al, 2004;Chiarle et al, 2007;Tobler et al, 2014;Frank et al, 2015Frank et al, , 2017, which may increase the magnitude and frequency of debris flows. Examples include rapid accumulation of sediment in the initiation zone (Evans et al, 2001;Rickenmann et al, 2001;Haeberli et al, 2002;Hauser, 2002;Hürlimann et al, 2003;Raymond et al, 2003;Huggel et al, 2004;Chiarle et al, 2007;Tobler et al, 2014;Frank et al, 2015Frank et al, , 2017, which may increase the magnitude and frequency of debris flows.…”

Section: Introductionmentioning

confidence: 99%

“…Landslides ranging from small (a few 1000 to 10 000 m 3 ) up to large-sized (≥ 10 6 m 3 ) events have been associated with increased debrisflow activity over time scales up to a few years (Rickenmann et al, 2001;Hürlimann et al, 2003;Stricker, 2010;Tobler et al, 2014;Frank et al, 2015Frank et al, , 2017Baer et al, 2017). Landslides ranging from small (a few 1000 to 10 000 m 3 ) up to large-sized (≥ 10 6 m 3 ) events have been associated with increased debrisflow activity over time scales up to a few years (Rickenmann et al, 2001;Hürlimann et al, 2003;Stricker, 2010;Tobler et al, 2014;Frank et al, 2015Frank et al, , 2017Baer et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Frank

Huggel

McArdell

et al. 2018

Earth Surf Processes Landf

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An increase in debris‐flow frequency is expected in steep Alpine catchments after the occurrence of a large landslide, such as a rock avalanche. Herein we describe changes in debris‐flow activity following increases in sediment availability due to landslides, or accelerated rock‐glacier movement, for five catchments in the Swiss Alps, the Spreitgraben, Schipfenbach, Bondasca, Riascio, and Dorfbach catchments. Documentation on debris‐flow activity is available from both before and after the landslide that generated the new sediment deposits. Data from nearby meteorological stations were used to explore possible changes in rainfall activity, and how the intensity and duration of rainfall events may have changed. In all cases there was a considerable increase in debris‐flows frequency for one to eight years following the landslide. The annual number of days with debris‐flow activity following the landslide was similar to that observed for the Illgraben catchment, where many such landslides occur annually. No clear change in precipitation totals preceding debris flows was apparent for the Riascio catchment, suggesting that the increase in frequency of debris flows is related to the increase in the amount of sediment that can be readily mobilized. In the two cases where rainfall data were available on an hourly basis, no systematic changes in the intensity or duration of rainfall related to debris‐flow triggering were apparent, as shown by the close‐clustering of storms on the intensity‐duration plots. Following the sediment‐generating event, an initial and sudden increase of the sediment yield was observed, followed by a decrease over time towards pre‐disturbance values. The response of the catchments appears to be related to the amount of debris‐flow activity prior to the landslide: sediment yield from catchments with frequent debris flows prior to the landslide activity did not increase as dramatically as in catchments where debris‐flow activity was less common prior to the landslide. © 2018 John Wiley & Sons, Ltd.

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Section: Spreitgraben Catchmentmentioning

confidence: 97%

Section: Spreitgraben Catchmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Frank

Huggel

McArdell

et al. 2018

Earth Surf Processes Landf

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“…For instance, sediment entrainment during a debris flow changes the volume of materials and flow behavior [55,56]. Simpler debris flow models do not replicate entrainment, but partly consider this process by including additional quantities of material at the debris initiation point, while more complex models explicitly replicate the spatially and temporally-distributed erosion of channel materials as the flow is propagated [57]. However, while a more complex model that includes entrainment can better replicate debris flow heights near the point of initiation [57], this additional process introduces another source of uncertainty into the model with the introduction of additional parameters (e.g., erosion rate), which require values that may not be known.…”

Section: Introductionmentioning

confidence: 99%

Application of Sensitivity Analysis for Process Model Calibration of Natural Hazards

2018

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Sensitivity analysis (SA) describes how varying inputs to a model subsequently varies its outputs. Its inclusion can support the systematic calibration of numerical models to back-calculate intensity properties of past torrent events that would otherwise be difficult or impossible to collect during their occurrence. Sensitivity analysis for model calibration is assessed with the back-calculation of a known torrent event. In particular, FLO-2D, a cell-based numerical model, is used to simulate the 2005 debris flow event that occurred in Brienz, Switzerland. Under 4000 simulations were completed with ranges of physically reasonable parameter values. Model results were compared in 3-dimensions with both sediment deposition extents (x, y) and estimated deposition heights (z) from available post-event images. The comparisons highlighted that more accurate input and validation data, namely the flow behavior of hazardous processes and post-event deposition heights, are required to produce stronger agreements between simulated and observed results. Furthermore, the application of SA for model calibration supports systematic exploration of large parameter spaces characteristic of complex phenomena like natural hazard events. These findings demonstrated how important model input factors can be identified, which provide guidance for future data collection efforts to capture both the rheology and the spatial distribution of hazards more accurately.

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Granular avalanches on the Moon: Mass‐wasting conditions, processes, and features

et al. 2017

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Seven lunar crater sites of granular avalanches are studied utilizing high‐resolution images (0.42–1.3 m/pixel) from the Lunar Reconnaissance Orbiter Camera; one, in Kepler crater, is examined in detail. All the sites are slopes of debris extensively aggraded by frictional freezing at their dynamic angle of repose, four in craters formed in basaltic mare and three in the anorthositic highlands. Diverse styles of mass wasting occur, and three types of dry‐debris flow deposit are recognized: (1) multiple channel‐and‐lobe type, with coarse‐grained levees and lobate terminations that impound finer debris, (2) single‐surge polylobate type, with subparallel arrays of lobes and fingers with segregated coarse‐grained margins, and (3) multiple‐ribbon type, with tracks reflecting reworked substrate, minor levees, and no coarse terminations. The latter type results from propagation of granular erosion‐deposition waves down slopes dominantly of fine regolith, and it is the first recognized natural example. Dimensions, architectures, and granular segregation styles of the two coarse‐grained deposit types are like those formed in natural and experimental avalanches on Earth, although the timescale of motion differs due to the reduced gravity. Influences of reduced gravity and fine‐grained regolith on dynamics of granular flow and deposition appear slight, but we distinguish, for the first time, extensive remobilization of coarse talus by inundation with finer debris. The (few) sites show no clear difference attributable to the contrasting mare basalt and highland megaregolith host rocks and their fragmentation. This lunar study offers a benchmarking of deposit types that can be attributed to formation without influence of liquid or gas.

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The importance of entrainment and bulking on debris flow runout modeling: examples from the Swiss Alps

Cited by 118 publications

References 36 publications

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Application of Sensitivity Analysis for Process Model Calibration of Natural Hazards

Granular avalanches on the Moon: Mass‐wasting conditions, processes, and features

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