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Quantifying and improving the protective capacity of forests against snow avalanches


Project description

Snow avalanches threaten human settlements and transportation lines in many mountainous regions throughout the world. Mountain forests reduce the probability of avalanche initiation and therefore are a valuable protective measure. However, the protective capacity of mountain forests varies with stand structure and can be influenced by different management strategies. If a forest has a protective function against avalanches, then expensive alternatives (i.e., snow supporting structures) do not have to be considered.


Figure 1. Avalanche tracks reaching Valle de las Trancas at Nevados de Chillán, Chile. The avalanches release from a South-facing slope and affect infrastructure located along this portion of the valley. Right-hand picture kindly provided by Felipe Hermosilla.

Future changes in climate and land-use are likely to change forest cover and composition, and thus have an impact on avalanche hazard mitigation. For an optimized management of mountain forest ecosystem to reduce disaster risk it is thus crucial (1) to increase the knowledge about forest-avalanche interactions, (2) to better integrate forest effects in existing avalanche dynamics models and risk analysis, and (3) to deduce adapted strategies for the management of different mountain forest ecosystems of the world.

This project is framed within the Ecosystems Protecting Infrastructure and Communities (EPIC) project and is funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). 

Figure 2. RAMMS simulation of avalanche release in the forest in Landschaft Davos.  

Project locations

The project will be conducted in three mountain regions of the world:

1. Chilean Andes: Valle de las Trancas, located in the region of Nevados de Chillán (36°55'S, 71°27'W) will represent our pilot study area in Chile. Other study areas may be included in the near future in areas where (i) avalanches are an issue for local communities and (ii) forest-avalanche interactions exist. For example, at Cajón del Maipo (33°46'S, 70°15'W), near Santiago de Chile, snow avalanches appear to reach local communities, which must be confirmed in-situ to include this location as one of our study areas.

2. Nepal: two potential study areas are foreseen. Firstly, the Annapurna Conservation Area, where snow avalanches have occurred in the past with an impact on forests, community infrastructure and livelihoods is considered. This conservation area was launched in 1986 and is both the largest and the first protected area in Nepal. It covers an area of 7,629 km2 and is home to over 100,000 residents. The other potential study area is the newly (2010) formed Gaurishankar Conservation Area, which covers 2,179 km2 and hosts over 56,000 residents.

3. Swiss Alps: most previous work on forest-avalanche interactions and avalanche modeling has been conducted in this region. Locations with well documented avalanche occurrence in the Swiss Alps will therefore allow to better calibrate and validate the models of avalanche dynamics and forest-avalanche interactions in different regions worldwide.


Peter Bebi (

Perry Bartelt (

Alejandro Casteller (

WSL Institute for Snow and Avalanche Research, SLF

Davos, Switzerland



Bartelt, P. and Stöckli, V. 2001. The influence of tree and branch fracture, overturning and debris entrainment on snow avalanche flow. Annals of Glaciology, 32: 209-216.

Bebi, P. Kulakowski, D. and Rixen, C. 2009. Snow avalanche disturbances in forest ecosystems – state of research and implications for management. Forest Ecology and Management, 257: 1883-1892.

Casteller, A., Christen, M., Villalba, R., Martínez, H., Stöckli, V., Leiva, J.C. and Bartelt, P. 2008. Validating numerical simulations of snow avalanches using dendrochronology: The Cerro Ventana event in Northern Patagonia, Argentina. Natural Hazards and Earth System Sciences, 8: 433-443.

Gruber, U. and Bartelt, P. 2007. Snow avalanche hazard modelling of large areas using shallow water numerical methods and GIS. Environmental Modelling & Software, 22: 1472-1481.

Teich, M. and Bebi, P. 2009. Avalanche protection forest in GIS-based risk analyses – a case study in ‘The Bannwald of Andermatt’, Switzerland. Forest Ecology and Management, 257: 1910-1919.

Teich, M., Bartelt, P,. Grêt-Regamey, A., Bebi, P. 2012. Snow avalanches in forested terrain: Influence of forest parameters, topography and avalanche characteristics on runout distance. Arctic, Antarctic, and Alpine Research, 44: 509-519.