Reliability-based design concepts in hydraulic engineering

: Different probability-based concepts for design of hydraulic structures are presented that could replace or complement traditional designs based on the concept of design load plus a safety margin. The traditional concept (here called Level I design) does not permit the assignment of the correct probability to the failure event. Concepts which are based on the correct probability of failure are based on descriptions of resistance and load as random variables. Level II design assumes these random variables to be Gaussian distributed. Level III is based on arbitrary distributions of load and resistance. Level II and III concepts are appropriate for evaluation of a design's reliability. Design Level IV is also based on the joint probability density function for loads and resistances; in addition, it requires the assignment of a consequence function to each combination of resistance and loads. The design concepts are illustrated with the design of a flood levee on a river.