Calibration of piping assessment models in the Netherlands

New insights into the failure mechanism piping (under-seepage) regarding the physical process as well as reliability aspects have led to a revision of the Dutch design and safety assessment rules for dikes. This paper describes how the required factor of safety for piping is derived from a top level requirements formulated in terms of an acceptable probability of flooding. The main steps herein are (a) to account for the length-effect to translate requirements on dike ring (system) level to admissible probabilities of failure on dike section (element) level and (b) the calibration of safety factors as a function of the (element) target reliability.