River System Behaviour Effects on Flood Risk

A risk-based safety approach is indispensable to support decision-making on flood protection strategies and measures. Hitherto the effects of river system behaviour on flood risk have usually been neglected. River system behaviour refers to the fact that the flood risk (or safety) of a particular area may depend on the safety of other adjoining areas. This paper presents a method for quantification of these effects. To this end state-of-the-art modelling techniques of the hydrodynamic loads on the flood defences and the geotechnical strength as well as a module for the estimation of flood damage have been integrated in a probabilistic framework. The method is illustrated by means of a case study, considering two dike failure mechanisms. Models of different degrees of complexity are applied to reduce the number of calculations for the computationally intensive hydrodynamic model.