After the catastrophic flooding of New Orleans due to hurricane Katrina, plans have been developed for the improvement of the flood protection system of the city. In this paper, we apply the principles used in the Netherlands for risk‐based design of flood protection systems to the New Orleans metropolitan area. In this so‐called economic optimization, the incremental investments in more safety are balanced with the reduction of the risk to find an optimal level of flood protection. Although the analyses are preliminary and not yet fully realistic, the presented outcomes indicate that for densely populated areas, such as the central parts of New Orleans, it could be justified to choose a higher protection level than the currently proposed level of 1/100 per year. The results of the economic optimization can be considered as technical advice that can be used as input for the (political) decision‐making.

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This paper presents an assessment of the multi-layered safety system in Tohoku, Japan based on the tsunami disaster of March 2011. The performed analysis has been based on data provided by local researchers and field observations. First an overview of the tsunami behaviour along the affected coastline of Tohoku is presented, which shows clearly that the disaster has site-specific features. The assessment that follows has a descriptive character and it is divided in two parts. First the performance of each safety layer in Tohoku is separately assessed, and conclusions are drawn for the efficiency of the system. The second part points out some implications of this disaster for the use of multi-layered safety in flood risk management.

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