In a densly populated country like Austria natural hazard prevention is of great importance. The Division of Torrent and Erosion Research develops guidelines to assess the risk stemming from torrents. Risk assessment is based on the exact analysis of catastrophic torrent events which have taken place in the past. Observations and surveys are to contribute to a better understanding of the intervening processes. Based on these findings it is possible to elaborate planning guidelines for control measures and hazard zoning in order to limit the impact of catastrophes.

Debris flows

Unlike in rivers where excess water consists the main threat, the main source of danger in torrents is stemming from debris (stones and fine material). Debris flows are a special thing. Debris flows are gravitation streams consisting of a water-debris-mixture where almost no water is discernible. Hydraulic laws laws apply only to a limited extent to debris flows. During recent years lot of damage was recorded in Austria and 32 persons were killed in the course of debris flow events. Outstanding events are addressed by the BFW by means of disaster analyses. For this purpose, significant parameters of debris flows having occurred in Austria since 1972 are being entered into a torrent disaster reference database.

Disaster analysis

The correct assessment of the risk potential provides the basis for any active or passive control measure in the case of floods and debris flows. For this purpose, we use the following methods

• the historical approach
  Written documents and eye testimonies from past torrent events
• the preventive method
  Assessment of future disaster scenarios, modelling supported by physical and mathematical laws.

Torrent Disaster Reference Database

Since 1972 the Forest Technical Service of the Torrent and Avalanche Control (WLV) has produced so-called flood accident files based on field inspections following a torrent disaster event. More than 4.000 reported floods in the period between 1972 and 2001 were entered into a database developed at the BFW. The results from this database supplied meaningful information summarising damages occurring during a torrent disaster. The table below shows some of the disaster catagories.

DOMODIS

The project DOMODIS ("Documentation of Mountain Disasters") was initiated under a IDNDR-Project ("International Decade of Natural Disasters Reduction"). The project is conducted in collaboration with the BMLFUW, the Unversity of Agricultural Sciences (Institute for Alpine Natural Hazards and Forest Engineering) and the BFW, Division of Torrent and Erosion Research. Based on the documentation method used so far for torrent disaster events DOMODIS envisages two objectives: 1. Improvement of technical-methodological aspects of event documentation and 2. Implementation of a suitable organisational structure for a survey covering the whole territory of Austria. This aspect makes the visible difference between DOMODIS and many other projects which serve only scientific purposes. As a component of natural resource analysis the project is to provide support for decision-making processes in the field of risk management.