Developments in levee reliability and flood risk analysis in the Netherlands

This paper presents and overview of advances in flood risk and levee reliability analysis in the Netherlands. It is described how new safety standards – in the form of a target failure probability – have been derived on the basis of nationwide flood risk assessments which taken into account both economic risk and risk to life. The process for derivation of semiprobabilistic design codes (i.e. factors of safety) for various geotechnical failure mechanisms of flood defences is described and it is shown how these semi-probabilistic requirements are consistent with the target probabilities of failure and ultimately with the underlying flood risk acceptance criteria. The newly introduced approach also raises challenges like the introduction of fully reliability based design and assessment techniques, but it also provides opportunities such as the use of reliability updating and data assimilation, which will be highlighted after discussing the framework and its overall coherence.