Laboratory experiments on the dynamics of powder snow avalanches in the run out zone
METADATA ONLY
Loading...
Author / Producer
Date
1991
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
METADATA ONLY
Data
Rights / License
Abstract
We report on laboratory experiments on the motion of powder-snow avalanches along a bent chute. The avalanches are simulated as turbulent boundary-layer flows of polystyrene particles in still water along a chute consisting of a straight inclined part, a curved part and a second, possibly inclined, run-out zone. An ultrasonic measuring technique is used to determine mean particle speeds (via the Doppler shift of the reflected signal) and the particle concentration (via the attenuation of the echoes). By ensemble averaging, individual turbulence effects are eliminated. As measuring procedures, profiles were determined for particle velocity and density across the boundary layer; these were taken (i) for the avalanche tail along the entire track, i.e. in the steep part and the run-out zone, and (ii) for the avalanche head in the run-out zone below the kink in the terrain. Moreover, time sections of velocity and density (i.e. time series at fixed positions along a line through the boundary layer) were recorded and the particle mass deposited in the various zones of the track was measured.
The analysis of the data reveals the following results: a concave change in the terrain topography acts as a very efficient mechanism for particle sedimentation, thus affecting particle concentration and velocity, and considerable reduction close to the ground, whereas the density is reduced throughout the depth, thus leading to a considerable reduction of dynamic pressure close to the ground and leaving it somewhat greater at higher altitudes. We conclude with practical considerations for the field glaciologist.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
37 (126)
Pages / Article No.
281 - 295
Publisher
International Glaciological Society
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Organisational unit
09599 - Farinotti, Daniel / Farinotti, Daniel