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Release date: March 1st 2010.

The RAMMS module AVALANCHE was developed to simulate flowing snow avalanches in complex terrain. The module is widely used in Switzerland for avalanche hazard studies.

The RAMMS::AVALANCHE module combines state-of-the-art numerical solution methods with helpful input features and user-friendly visualization tools.  Many of the input and output features have been optimized to allow engineers in practice to easily modify hazard scenarios and control simulation results.

The core of the program is an efficient second-order numerical solution of the depth-averaged avalanche dynamics equations. Avalanche flow heights and velocities are calculated on three-dimensional digital terrain models. Single or multiple release areas are easily specified using GIS type drawing features. Users are provided with useful overview information of simulations, including all-important information of the release area (mean slope, total volume), flow behaviour (max flow velocities and heights) and stopping behaviour (mass flux).  Maps and remote sensing imagery can be superimposed on the terrain models to aid the specification of input conditions and calibrate the model with known events.

The model still relies on the two-parameter Voellmy model widely used in Swiss snow engineering practice. To calibrate the RAMMS Voellmy-model, we used data from our real scale avalanche test site in Vallée de la Sionne, VS, Switzerland. Special user features have been introduced into the model to account for variable surface roughness, vegetation and flow in forests. Swiss guideline suggestions for friction parameters (based on extensive model calibration) are also available for practical users.


The development of the RAMMS::AVALANCHE module started in 2005 and is based on experience with the one-dimensional simulation tool AVAL-1D.  (Two-dimensional terrain profiles with known flow width are used to model the avalanche track.)  RAMMS::AVALANCHE is now in use in over 70 locations worldwide and the software has been successfully applied in mountain regions such as the Alps, Himalayas, Andes, Rocky Mountains, Tatras and others.  Behind RAMMS::AVALANCHE is a staff that can help with installation, modeling and application problems. Several user workshops are held every year, where engineering applications are discussed. Feedback from all corners of the world is used to improve RAMMS. New program updates are released at regular intervals.


Future Developments


Avalanche dynamics research in Switzerland is now undergoing massive improvements, driven by recent theoretical and experimental research results. The RAMMS::AVALANCHE model is now being updated to include many of these results and offer advanced model functions to specialized users – located primarily at other research organizations.


One of the primary results is in the inclusion of the fluctuation energy of the snow granules – which greatly effects flow friction, producing flow regime transitions (solid-like tails and dilute flow fronts). A variable density avalanche model is now being tested that should help reproduce avalanche impact pressures more accurately.  Since the production of fluctuation energy is mass dependent, entrainment processes will be included in model updates. Many countries in the world have wet snow avalanche problems and a special wet snow avalanche model is now under development. This model will account for high snow temperatures and predict the free water content in the flow providing the necessary state variables to model snow gliding and levee formation.


Users are also interested in modeling small, frequent avalanches. In this area we are working on the specification of initial conditions (snowpack structure and collapse) as well as defining useable digital terrain models.Considerable calibration of small avalanche events is underway.


Finally, the physical boundary conditions for air-blow out from the granular core are being formulated. This will allow the coupling of RAMMS::AVALANCHE to a new powder snow avalanche code which can be used to model full mixed flowing/powder avalanches in three-dimensional terrain in the near future.


The RAMMS team welcomes future research collaborations with other organizations.

For further information please consult the RAMMS AVALANCHE user Manual



Case studies


1) Vallée de la Sionne, VS, Switzerland


In our real scale test site we have accurate data from different dry and wet snow avalanches events from 1999 until today. This gives us the opportunity to test and calibrate the models. We can compare measured speed, run out distances and pressure directly with model results. The presented dry snow avalanche occured in March 2006.



animation_maxflow_VdlS_klein  animation_maxvelocity_VdlS_klein

2) Dorfberg, GR, Switzerland     

The popular freeride slopes of the Dorfberg are located right next to the SLF building in Davos. In March 2008 a large wet snow avalanche released close to the top of Dorfberg (2536m a.s.l), ran through the narrow gully Salezer Tobel and ran out on the gentle slope at the bottom next to the lake Davos.










© SLF/WSL 2010