Risk-based design of flood defence systems: a preliminary analysis of the optimal protection level for the New Orleans metropolitan area

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.