Link zu WSL Hauptseite Swiss Federal Institute for Forest, Snow and Landscape Research WSL

Research conducted by WSL in Valais

For many years the Canton of Valais has been a key partner in the research activities and services of the WSL relating to avalanches, debris flows, rockfalls, forestry issues and climate change. As a mountainous region, Valais is directly affected by climate change and natural hazards, and is therefore eager to collaborate with researchers. The canton supports the branch station in Sion and the WSL's research projects not only in principle, but also financially and logistically. As a landscape that serves as an open-air laboratory, Valais is an ideal venue for research in the natural sciences and on environmental issues. The WSL operates more research facilities here than in any other canton.

History of collaboration between the WSL and the Canton of Valais


At the beginning of the 1990s the then Natural Hazards Commissioner of Valais, Charly Wuilloud, and the then Director of the WSL Institute for Snow and Avalanche Research SLF, Walter Ammann, decided to formalise the scientific collaboration between the two bodies by means of drawing up an official agreement .

The accord arising from their decision was signed in 1995, a year additionally marked by the opening of the Valais branch of the SLF in Sitten. The creation of a globally unrivalled avalanche testing site in Vallée de la Sionne (Arbaz district) launched a period of fruitful cooperation between the WSL and the canton.

Developing avalanche research activities was not the sole purpose of this agreement. A key object was to extend the scope of research work to encompass all natural hazards. In the intervening period numerous large facilities, as well as testing and monitoring sites, have been established, including for the investigation of forestry issues, drought and climate change, e.g. in the Illgraben catchment zone for debris flow research, in St. Léonard for rockfall processes, in the Matter and other valleys for permafrost and slope movements, in several rivers that flow through the canton for bedload, in Leuk for forest fire research, in Leuk/Susten for forest rejuvenation experiments (rain canopy installation) and a long-term irrigation trial (Pfynwald), and in various dry valleys in the canton for investigating forestry issues and drought.

The new agreement of September 2016 between the Canton of Valais and the WSL covers the areas of natural hazards management, forest conservation and management, climate change, rural development and biodiversity. The overriding goal is to enhance applied research in these fields within the canton.

Overview of WSL research sites in Valais

  • Vallée de la Sionne (Arbaz district): avalanche dynamics, large avalanches
  • Illgraben, Randa (Dorfbach), Agarn (Meretschibach): debris flow observation
  • St. Léonard: rockfall processes (2009-2011)
  • Matter and other valleys: permafrost, slope movements
  • Various rivers: bedload
  • Leuk and Visp: two sites for the long-term forest ecosystem research (LWF) programme
  • National Forest Inventory (LFI): approx. 80 sampling areas a year
  • Four sites for the Sanasilva (forest health) project
  • Leuk forest fire site: post-wildfire regeneration
  • Leuk / Susten: drought / rain canopy installation (2003-2014)
  • Pfynwald: drought / irrigation experiment
  • Lötschental, altitudinal gradients: forests and climate change
  • 51 IMIS stations and 53 observers for avalanche warning purposes
  • Mountland project: climate change
  • Four natural forest reserves

Selection of WSL research projects and test sites in Valais:

Vallée de la Sionne Avalanches / Vallée de la Sionne (Arbaz district)
  • Test facility for experiments involving large avalanches
  • Extensive measurement infrastructure in the avalanche path (mast, wedge, wall, radar, bunker)
  • Outcomes: precise knowledge of the forces and motion sequences of large avalanches (velocity, compression forces, mass balance etc.), development of simulation software for land allocation and protection, guidelines on protective measures


Debris flow observation and warning system / Illgraben catchment zone
  • Automatic measuring infrastructure in the stream channel for recording the characteristics of natural debris flow events (geophones, radar, laser and ultrasound sensors, debris weigher, shear wall, video recording)
  • Warning system with visible and audible alarms within an emergency plan
  • Outcomes: better understanding of the processes involved in debris flows in channels and the initiation of debris flows, optimisation of debris flow models for danger assessment purposes, improved warning systems to protect the public

Irrigation project in Pfynwald forest
  • Effects of long-term irrigation of a native pine forest, compared to natural drought conditions
  • Measurement of around 50 parameters from roots to crown
  • Outcomes: a more thorough understanding of the influence of (alleviated) drought on the carbon and water balance of the forest ecosystem
Leuk Forest fire sites in Leuk and Visp
  • Data gathering on vegetation change and insect diversity over a period of around 10 years
  • Analyses relating to the development of species variety and forest rejuvenation in Leuk, and long-term survey of forest rejuvenation in Visp

Waldverjüngung Forest rejuvenation in dry regions
  • Sample surveys of local pine and downy oak in the canton of Valais, and of forest rejuvenation in Pfynwald forest
  • Experiments relating to the influence of drought on the rejuvenation of indigenous and foreign pine species (Pinus sylvestris, P. nigra, P. halepensis)