Windstorms and risk analysis related to forest damage in the Swiss Alps using GIS techniques

Project funded by the Swiss Agency for the Environment, Forest and Landscape (SAEFL) Severe meteorological conditions, such as windstorms, extreme precipitation and heat and cold waves trigger major natural hazards such as floods, droughts, and landslides, and result in loss of life and high levels of economic losses. The rate of climatic change expected for the 21st century may result in an increase of extreme climatic events in European countries like Switzerland (1). In the 1990s, two severe windstorms destroyed and damaged a significant area of Swiss forest cover. The Vivian storm (27.02.1990) damaged a total of 4,928 ha (2), while the Lothar storm (26.12.1999) damaged 26,600 ha (3). For these reasons, it is imperative to analyse the past and present evolution of such windstorms to attempt to quantify future risks and impacts in order to mitigate economic costs associated with such damages. The aim of this study is to analyse the sensitivity of the Swiss alpine forest in terms of risk-prone zones, in relation to extreme climatic events like windstorms. With the help of Geographical Information System (GIS) techniques, the areas at risk in Swiss forests can be identified according to their terrain characteristics (altitude, slope, and exposure to weather elements). The analysis of windstorm forest damage in the past (e.g., the 1990 Vivian and 1999 Lothar storms) has allowed us to identify the most sensitive zones for current studies. References: (1) IPCC, Climate Change 2001. Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, New York, 2001 (2) OFEFP/SAEFL (Office Fédérale de l’Environnement des Forêts et du Paysage), Dégâts provoqués par la tempête de 1990 dans les forêts Suisses, Cahier de l’environnement N° 218 Forêts, Berne, 1994 (3) Angst C., Lässig R., Brang P., Le reboisement après Lothar. Créer des peuplements résistant aux tempêtes, La Forêt, 53 (11), 13-16, 2000. Translation of Nach Windwürfen stabile Bestände schaffen, Wald und Holz 81 (8): 27-30, 2000.