Spatial explicit multicriteria flood risk – fundamentals and semantics of multicriteria flood risk assessment

The management of floods and their consequences is increasingly in the focus of decision-makers and the public since a series of catastrophic flood events hit Europe e.g. in the Oder basin in 1997 and 1999 and in the Elbe basin in 2002. In the last three decades, the number of reported flood disasters throughout Europe has increased dramatically. Whilst only 31 disastrous events were reported in the period from 1973 to 1982, 179 events took place between 1993-2002. Following this series of events the European Parliament and Council established the directive on the assessment and management of flood risk. This directive aims at managing flood risk in order to reduce flood damage. One important step of this directive is the creation of flood risk maps. Flood risk assessment and mapping is a fundamental part of flood risk management. Its products provide decision-makers, experts and the public with the necessary information for the planning and implementation of risk mitigation measures, since it identifies regions with unacceptable high risk. Traditional assessment approaches focus on the identification of economic flood risk, i.e. the damage on households, industry and commerce. The social and environmental dimension of flood risk is often neglected. In this chapter, we introduce a multicriteria approach for the integrated assessment and mapping of all consequences of flooding. In this context, we present the fundamentals and semantics of assessing multiple damages for tangible (i.e. market) as well as intangible (i.e. non-market) assets demonstrated in a case study. We show how individual, asset-specific flood risks can be aggregated into multicriteria risk scenarios and highlight how these scenarios reflect different requirements and preferences of stakeholders and describe the uncertainties inherent to the approach.