Avalanche Cartography: Visualization of Dynamic-Temporal Phenomena in a Mountainous Environment

Avalanches represent a very short, local, dynamic event in snow-covered mountainous regions. They are not easy to predict and often can produce devastating results. Avalanche cartography deals with the causes and consequences of such incidents and attempts to depict them in a variety of ways. The most common cartographic representation within this field is the avalanche hazard map. It incorporates mainly large-scale topographic elements with thematic features. However, besides just visualizing what has happened and depicting locations of potential risk, it is now possible within modern cartography to experiment with different approaches and to visualize complex variables in a cartographically demanding way. This paper deals with the phenomena of avalanches from a cartographic perspective and shows the variety of possibilities cartography can offer today to understand and predict these complex natural hazards. Introduction n February 23, 1999, an avalanche struck the village of Galtür, Austria, killing 31 people. This tragedy, and a spate of other alpine disasters in recent years, has increased interest in the spatial analysis of avalanches in Austria. This trend could be seen during the state of emergency in the upper Paznaun Valley, Tyrol, also during February 1999, when more than 35 people lost their lives in several avalanches. The news media and officials in their briefing rooms noticeably relied on cartographic representations for explaining events and for evidence-based decision making. Despite the breaking news stories and attempts to explain the destructive and dynamic components of the catastrophe through traditional reporting, public interest was focused almost exclusively on three-dimensional cartographic representations. Portraying the avalanches in a spatial context allowed the concerned public to see complex correlations in a vivid and more conclusive way as the magnitude of O the disaster began to unfold. Maps and map-related products provided an important public service throughout this ordeal. Avalanches are common natural occurrences in mountainous regions during the snow season. They are terrifying spectacles, and remarkable – if watched from a remote and safe distance. Although an avalanche is usually only a short and localized event, the results can be disastrous if inhabited areas are involved. Besides temporarily closing off important transportation routes, such as passes, roads, and railroads, their track of destruction can destroy roads, protective forests, buildings, and all of one’s personal effects. The ultimate tragedy is the loss of human life. How does cartography deal with avalanches, their effects, and their three-dimensional representation? Avalanches develop primarily because of topographic and meteorological factors. Hardly predictable, avalanches are also difficult to pinpoint in the environment. Various dynamic processes have to be taken into consideration, which may in turn be influenced by many unpredictable factors. The following elements play an important role: snow properties; wind; temperature; sunlight exposure and intensity; slope; aspect; and terrain features. From the cartographer’s point of view, all of these interrelated factors have to be portrayed in context on a map. Therein lies the challenge. The art of simplifying real-world three-dimensional space into a spatial model without omitting essential features still remains an important, albeit tricky, task for cartographers. Thus a map can be considered as a model of reality. Large-scale topographic maps are well suited for showing terrain-specific parameters that influence and interact with avalanches. Slope and aspect, the major topographic features most often used to predict avalanche occurrence, can be derived easily from topographic maps. The features that characterize recurring avalanche events – catchment areas, avalanche tracks, areas of avalanches, and danger zones – can also be locally delineated on topographic maps. The representation of these features is strictly dependent on the map scale and the extent of generalization. All delimitations on maps, including areas of avalanche risk, are to a certain extent Dr. Karel Kriz, Department of Geography and Regional Research, University of Vienna, Universitaetsstrasse 7, A-1010 Vienna, Austria. Tel: (+43 1) 4277 48641. Email: [email protected]