ABSTRACT
The requirement of reproducibility involves ensuring that the selected method of hazard assessment is transparent. In this way, the procedure, the applied approaches and methods, together with the interpretation if the compiled data can be more easily checked. This is also important because an exact evaluation of the process assessment is difficult even after the occurrence of a (larger) event. After Kienholz (1999), therefore, the following basic rules should be adhered to:
• comprehensive documentation (cartographic presentation) of all the relevant perimeters (areas of initiation and of impact of hazard, i.e. the torrent catchment area and the alluvial fan)
• clear choice of methods and their combination and their reporting • clear-cut decision criteria in the final evaluation • provision of evidence for identified sub-processes (whose existence can be quali-
fied through traces of earlier events either as “proven”, “assumed” or “potential”)
6.2 PROCEDURE OF HAZARD ASSESSMENT AND IMPORTANT ASPECTS
In Switzerland, the national platform for natural hazards Planat (2000) published recommendations for quality assurance in the assessment of natural hazards. According to this document, the most important elements of the hazard assessment are:
• event documentation/analysis of causes • map of the phenomena
• hazard map • risk analysis • specific hazard assessment for selected critical locations • protective measures/early warning systems
With regard to and based on the procedure for the hazard assessment, the following sub-steps can be derived. These sub-steps are briefly summarized in connection with the recommendations produced in Switzerland (BWW/BRP/BUWAL 1997; BUWAL/ BWW/BRP 1997):
The event documentation and the analysis of causes (especially after large and important events) represent important tasks in the compilation of the basic data. They include investigations of earlier events in the catchment, the dominant processes, the areas affected, the damage observed, and the triggering factors such as the meteorological conditions. A detailed documentation with the analysis of causes also examines how the event evolved and why damage was caused. Potential hazard processes are documented with the map of the phenomena, which can be derived primarily on the basis of characteristics observed in the field and indicators (traces). This map also represents an important part of the fundamentals.
