ABSTRACT
Risk based decision making has become increasingly important in many different disciplines like the financial or health sector, engineering and technical issues, biodiversity, nuclear technology or terrorism prevention for many years or even decades. The risk concept has also become widespread in the field of natural hazards management in the last 10 years because coping with complex systems requires a systematic analysis of scenarios and its consequences and a subsequent analysis and if necessary an adapted risk reduction strategy. In the last decade first recommendations and guidelines for risk-based decision making addressing practitioners were developed in Switzerland (Borter 1999b; Borter 1999a; Wilhelm 1999). After the catastrophic flood in 1987 the general strategy for dealing with natural hazards in Switzerland changed from a hazard-oriented more and more to a risk-based approach. After the natural hazard events in 1999 (SLF 2000; BWG 2000; WSL and BUWAL 2001) the national platform PLANAT was commissioned to elaborate a national strategy for dealing with natural hazards in future. The basic framework of this strategy is the risk concept. Based on this risk concept, between 2005 and 2008 several instruments were developed. The goals of these instruments are:
• sensibilisation of practitioners for risk-based decision making
• education of students and practitioners • providing guidelines for risk-based planning • risk-based optimization of financial resource allo-
cation for the realisation of countermeasures
The spatial resolution of data and the quality of assumptions in risk assessment should correspond to the required level of detail of an assessment. A general overview about the risk situation of a region demands the consideration of only the most dominant scenarios and the most important objects. A detailed analysis of a local safety problem needs the integration of all possible but realistic scenarios and the assessment of each individual object regarding its vulnerability and the expected damage. Therefore, the requirements of a risk assessment demand different tools, each fulfilling the required level of detail. In this paper a guideline and two tools, which address different levels of detail, are presented:
1. Guideline for the application of the risk concept (RIKO)
2. Online tool RiskPlan 3. Online tool EconoMe
2 THE GUIDELINE RIKO AS METHODOLOGICAL BASIS
The guideline RIKO is developed on the general risk concept as methodological basis, which is illustrated in figure 1. The main components of the risk concept are risk analysis, risk evaluation and risk management. In a risk analysis the question ‘‘What can happen?’’ is addressed, in risk evaluation the question ‘‘What may happen?’’ and finally in risk management the question ‘‘What needs to be done?’’. These three questions are part of every day risk-based decisions. The guideline RIKO consists of two parts:
• In part A the general risk concept is introduced for the processes snow avalanche, debris flow, rock fall, landslide, storm, hail, extreme temperature and earthquake.
