Recent years have seen a rapid development of a modern understanding of flood risk management. This entails the advancement of traditional flood defence approaches towards a more holistic understanding of the sources, processes and consequences of flooding, as well as stakeholders, strategies and options for reducing risks. Task 12 produced a framework for the ex-post (i.e. after implementation) evaluation of measures and instruments intended to reduce flood risk. Criteria, indicators and evaluation methods are provided to help users to evaluate past risk reduction practice, in order to improve flood risk management in the future. The methodology addresses criteria effectiveness, efficiency, robustness and flexibility.

To allow such an evaluation, a classification of all possible measures and instruments was needed, and a thorough investigation and discussion on assessment criteria. The task was interdisciplinary in the sense that it drew upon knowledge and approaches from technical sciences, economics, ecology and geography. The lists of measures and instruments and results were shared with Task 14, which looked at ex-ante (i.e. pre-implementation) evaluation.

The research is of relevance to practitioners who wish to understand more about the intended and unintended effects, effectiveness and efficiency of past flood risk management activities.

Key words: ex-post evaluation, flood risk management, structural measures, non-structural measures, instruments, indicators