Exploring the fire danger and exposition of settlements at the wildland urban interface: a case study in Graz, Austria

Changing climate is likely to increase the intensity of forest fires in Austria. Consequently, the investigation of the fire danger situation at the wildland-urban interface is crucial for the planning of prevention measures against future damages. Hence, a comprehensive fire risk assessment study was performed for Austria, in which five components were considered (natural cause for ignition of forest fires, socioeconomic causes for ignition, vegetation structure, meteorological factors and exposition of important infrastructures). The approach for the fire danger assessment determined for the city of Graz, the second largest city in Austria, as high danger level for fire occurrences. Therefore, the present work introduces a case study for this city, focusing on the exposure of settlements and infrastructure to fire events. The relevant infrastructure features were selected, such as residential buildings, power lines, radio stations, railways, highways and traffic and communication buildings, as well as three types of forests with different management objectives (production forest, site protection forest and object protection forest). In order to analyze the interaction between settlements and vegetation in case of forest fires, buffers were used (i.e. buffer sizes for buildings are 10m, 50m and 150m and other settlements are 60m, 100m and 200m). Infrastructure and forest cover were also classified due to their importance: high, medium and low risk of exposition. For example, production forest was considered to bear a lower risk of exposition due to their economic importance compared to protection forests, that have to protect the city from natural hazards like rock falls or mudflows. On the other hand, radio stations carry a high risk of exposition because of their importance for facilitating the communication of the community. In combing the results of the fire danger assessment for the city of Graz with final exposition map the results indicate that areas around radio stations situated in the northwestern area of the city have a higher risk of exposition. As a result, firefighters must pay particular attention to this region for management and evacuation plans.