SUMMARY
Flood risk management in the context of Integrated Water Resource Management (IWRM) is becoming widely accepted as an approach to improving resilience in light of increasing flood risks due to climate change and other factors. This paper contributes to a better understanding of the governance arrangements needed for effectively implement integrated approaches to managing flood risk. We compare how IWRM and flood risk management have been operationalized within “top-down” and “bottom-up” governance arrangements in the European Union and the United States. We focus in particular on two case study regions, the Catalan coastal region in Spain and the San Francisco Bay Area in California, which have strong similarities in economy, climate, and environmental values, but different institutional settings. Our findings contribute empirical evidence of the need for a balance between “top-down” and “bottom-up” approaches. While the San Francisco Bay Area’s strongly collaborative and participatory approach has generated new connections among flood managers and other stakeholders, the lack of a central entity with the capacity and mandate for on-going coordination and region-wide risk assessments appears to constrain its ability to support integrated and adaptive management. The European Union’s top-down approach and the presence of a central authority at the river basin scale have led to a consolidated regional plan in Catalonia encompassing all phases of flood risk management, but the degree of engagement and opportunities for knowledge-sharing among participants may be more limited.