Flood risk perceptions applied to a spatial multi-criteria analysis in the Ebro Delta in Spain

The conventional method of risk analysis (with risk as a product of probability and consequences) does not allow for a pluralistic approach that includes the various risk perceptions of stakeholders or lay people within a community or region. In river basins, it is often an expert-based economic analysis of land use values that serves as the underlying estimation of costs. Intangibles such as nature development, biodiversity and cultural heritage are difficult to include in the calculation. Yet, local knowledge can be used to develop a realistic approach to outweighing tangibles and intangibles of land use values, as well as developing new approaches to risk management. This can be important to find appropriate solutions for the mitigation of risk. This presentation introduces a methodology that combines the virtues of three different methods used for risk analysis: the quantifiable conventional approach to risk, the taxonomic analysis of perceived risk and the analytical framework of a spatial multicriteria analysis. The combination of these methods is applied to the case study ’Ebro Delta’ in Spain as part of the European 6th framework project ’Floodsite’. The new approach using this combination is the incorporation of risk perceptions and its application and operationalisation in a multi-criteria analysis. Risk perception is derived from the psychometric paradigm that distinguishes a variety of risk characteristics. Due to a number of similarities among these risk perceptions all known risk characteristics can be condensed into three higher order risk characteristics - awareness, worry and preparedness. This reduction of risk characteristics enables scientists to employ them as weights in a multi-criteria analysis. Risk perception information has been collected with help of an on-site survey. The result is significant levels of ’worry’ and ’awareness’ of the flood risk with an increasing demand for ’preparedness’. Risk perception enters the multi-criteria analysis as complementary weights for the criteria risk and benefit. The results of the survey are applied to a set of scenarios representing both sea level rise and land subsidence for a time span of fifty years. Land use alternatives that are based upon the given scenarios have been presented to stakeholders and evaluated. For effective land use policy in flood prone areas it can be useful to compare land use alternatives based upon their performance with respect to risk and benefit. In this way the regional decision maker has been given an overview of preferences for handling risk. Even with limited resources a characteristic ’risk profile’ could be drawn that enables the decision maker to develop a suitable land use policy or at least provide a basis for further social learning processes.