Hazard Mapping Method for Dangerous Torrent Threatened by Debris Flow : On the Basis of Discussion at the International Workshop on Hazard Mapping in Salzburg, Austria

Hazard map is a topographic map on which dangerous areas threatened by debris flow, slope failures, landslides, snow avalanches and so on are optically expressed by red and yellow color zoning. In order to introduce necessary arrangement for warning and evacuation system or appropriate land use decision as so called soft countermeasures against natural disasters, it is quite important and effective to prepare hazard map as basic data and information for the implementation of such soft countermeasures. Also in Japan in recent years hazard maps and mapping methods are gradually introduced under the cooperative works among state, prefectural and local governments. Nowadays hazard maps are already exhibited to the public in Japan. However real zoning results of hazards by natural disasters are not expressed in hazard maps but only dangerous torrents or points are expressed in restricted manner. On the contrary, in Austria that has relatively long history and much practical experiences in the field of hazard mapping, there exist comprehensive arrangement and exhibition of hazard maps to the public under a certain legal background since 25 years ago. A special workshop on “Hazard Mapping Methods” was organized by the federal authority for torrent and avalanche control of the Ministry of Agriculture and Forestry at Rauris in the Federal State Salzburg in Austria from15th to 18th June 1998. The Workshop was arranged under the framework of IUFRO subdivision S8.04 for Natural Disasters with special focusing on the practical methods for hazard mapping. We had an opportunity to attend to this workshop and to discuss with foreign experts in this fields from Austria, Germany, Republic China, Italy and Slovenia. This Report is to give general informations on hazard mapping system in Austria and further a short introduction of the workshop itself and some important remarks on the main discussion points about the methods of the hazard mapping