Flow, flow transition and runout distances of flowing avalanches

Salm, B.

doi:10.3189/s0260305500011551

Cited by 99 publications

(65 citation statements)

References 6 publications

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“…Meanwhile, researchers and engineers developed and used mathematical models considering an avalanche as a moving solid block. The PCM (Perla, Cheng and McClung) [64] and VSG (Voellmy, Salm, Gubler) [65] models are two widely known examples. Only in the late 1980s did the hydraulic approach find its recognition in the western scientific literature.…”

Section: Comments To a History Of Dense Avalanche Hydraulic Modelsmentioning

confidence: 99%

A Review of Russian Snow Avalanche Models—From Analytical Solutions to Novel 3D Models

2020

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The article is a review of mathematical models of snow avalanches that have been proposed since the middle of the 20th century and are still in use. The main attention is paid to the work of researchers from the Soviet Union and Russia, since many of their works were published only in Russian and are not widely available. Mathematical models of various levels of complexity for avalanches of various types—from dense to powder-snow avalanches—are discussed. Analytical solutions including formulas for the avalanche front speed are described. The results of simulations of the movement of avalanches are given that were used to create avalanche hazard maps. The last part of the article is devoted to constructing models of a new type, in which avalanches are considered as laminar or turbulent flows of non-Newtonian fluids, using the full (not depth-averaged) equations of continuum mechanics. The results of a numerical study of the effect of non-Newtonian rheology and mass entrainment on the avalanche dynamics are presented.

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Section: Comments To a History Of Dense Avalanche Hydraulic Modelsmentioning

confidence: 99%

A Review of Russian Snow Avalanche Models—From Analytical Solutions to Novel 3D Models

2020

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“…RAMMS has been developed in the Swiss Federal Institute for Forest, Snow and Landscape research (WSL) [73] to simulate the runout of muddy and debris-laden flows in complex terrain. The model uses the Voellmy-Salm fluid flow continuum model [74] based on the Voellmy fluid flow law [75]. In the model, the frictional resistance is divided into two parts: a dry-Coulomb type friction, proportional to the normal stress at the flow bottom (coefficient µ) and a viscous resistance turbulent friction depending on the square of the velocity (coefficient ξ (m/s 2 )).…”

Section: Numerical Simulationsmentioning

confidence: 99%

Modelling the 2012 Lahar in a Sector of Jamapa Gorge (Pico de Orizaba Volcano, Mexico) Using RAMMS and Tree-Ring Evidence

Franco-Ramos

Ballesteros‐Cánovas

Figueroa-García

et al. 2020

Water

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A good understanding of the frequency and magnitude of lahars is essential for the assessment of torrential hazards in volcanic terrains. In many instances, however, data on past events is scarce or incomplete, such that the evaluation of possible future risks and/or the planning of adequate countermeasures can only be done with rather limited certainty. In this paper, we present a multiidisciplinary approach based on botanical field evidence and the numerical modelling of a post-eruptive lahar that occurred in 2012 on the northern slope of the Pico de Orizaba volcano, Mexico, with the aim of reconstructing the magnitude of the event. To this end, we used the debris-flow module of the rapid mass movement simulation tool RAMMS on a highly resolved digital terrain model obtained with an unmanned aerial vehicle. The modelling was calibrated with scars found in 19 Pinus hartwegii trees that served as paleo stage indicators (PSI) of lahar magnitude in a sector of Jamapa Gorge. Using this combined assessment and calibration of RAMMS, we obtain a peak discharge of 78 m3 s−1 for the 2012 lahar event which was likely triggered by torrential rainfall during hurricane “Ernesto”. Results also show that the deviation between the modelled lahar stage (depth) and the height of PSI in trees was up to ±0.43 m. We conclude that the combination of PSI and models can be successfully used on (subtropical) volcanoes to assess the frequency, and even more so to calibrate the magnitude of lahars. The added value of the approach is particularly obvious in catchments with very scarce or no hydrological data at all and could thus also be employed for the dating and modelling of older lahars. As such, the approach and the results obtained can be used directly to support disaster risk reduction strategies at Pico de Orizaba volcano, but also in other volcanic regions.

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“…To model frictional resistance S = (S x , S y ) in wetsnow avalanche flow, we apply a modified Voellmy model (Voellmy, 1955;Salm et al, 1990;Salm, 1993;Christen et al, 2010),…”

Section: Flow Frictionmentioning

confidence: 99%

“…Wet-snow avalanches are therefore treated as dense granular flows in the frictional flow regime (Voellmy, 1955;Bozhinskiy and Losev, 1998). Because measured velocity profiles of wet-snow avalanches exhibit pronounced viscoplastic, plug-like character, they are often modeled with a Bingham-type flow rheology (Dent and Lang, 1983;Norem et al, 1987;Salm, 1993;Dent et al, 1998;Bartelt et al, 2005;Kern et al, 2009). Bartelt et al (2015) uses cohesion to reduce the random kinetic energy of the avalanche core which effectively hinders avalanche fluidization and prevents the formation of mixed flowing/powder avalanches (Buser and Bartelt, 2015).…”

Section: Introductionmentioning

confidence: 99%

Reply to Reviewer 2

Cesar¹

2017

Preprint

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Snow avalanche motion is strongly dependent on the temperature and water content of the snow cover. In this paper we use a snow cover model, driven by measured meteorological data, to set the initial and boundary conditions for wet-snow avalanche calculations. The snow cover model provides estimates of snow height, density, temperature and liquid water content. This information is used to prescribe fracture heights and erosion heights for an avalanche dynamics model. We compare simulated runout distances with observed avalanche deposition fields using a contingency table analysis. Our analysis of the simulations reveals a large variability in predicted runout for tracks with flat terraces and gradual slope transitions to the runout zone. Reliable estimates of avalanche mass (height and density) in the release and erosion zones are identified to be more important than an exact specification of temperature and water content. For wet-snow avalanches, this implies that the layers where meltwater accumulates in the release zone must be identified accurately as this defines the height of the fracture slab and therefore the release mass. Advanced thermomechanical models appear to be better suited to simulate wet-snow avalanche inundation areas than existing guideline procedures if and only if accurate snow cover information is available.

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Flow, flow transition and runout distances of flowing avalanches

Cited by 99 publications

References 6 publications

A Review of Russian Snow Avalanche Models—From Analytical Solutions to Novel 3D Models

A Review of Russian Snow Avalanche Models—From Analytical Solutions to Novel 3D Models

Modelling the 2012 Lahar in a Sector of Jamapa Gorge (Pico de Orizaba Volcano, Mexico) Using RAMMS and Tree-Ring Evidence

Reply to Reviewer 2

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