Towards a reliable and cost-efficient flood risk management: the case of the Basque Country (Spain)

Economic resources to deal with natural hazards are usually limited. In the case of a highly affected territory in terms of floods, this means that they must be spent in an optimal way in order to reduce as much risk as possible. In this situation, flood risk management policies should always be supported by a quantitative scheme so that inequalities can be avoided. Cost–benefit analysis is a common applied tool, albeit it requires an accurate estimation of averted flood damages if their results are to be reliable. In fact, there are several sources of uncertainty in flood risk calculations that must be addressed before any conclusions may be drawn. In addition, other factors, such as social and environmental impacts, should be accounted for too within a multi-criteria analysis. Here we present a comprehensive approach of this sort that has been successfully developed in the Basque Country (northern Spain) in order to define the best possible flood risk management strategy. Starting with a macro-scale analysis to identify areas where a special attention must be paid, it makes use of detailed vulnerability data to select the best mitigation measures at a meso-scale level. This outstanding availability of information, together with a proper validation exercise, makes the methodology feasible and able to provide decision-makers with the necessary arguments to sustain their choices.