ABSTRACT
In the southwest of the Netherlands a storm surge barrier is under construction in the waterway that gives access to the port of Rotterdam. A feasibility study into the effect of an extra harbour entrance to the sea is being performed. The entrance requires a second barrier. Combined with dikes along the rivers, the barriers have to provide the required safety against flooding. The study is concentrated on the influence of the second barrier on design water levels for dikes which were already set by the first barrier. The frequency of closure for both barriers has to be minimized, because of harbour interest. With this restriction, no significant increase in design water levels is allowed. A hydraulic network model is used to calculate the effect of the barriers on water levels. To calculate design water levels an efficient probabilistic calculation procedure is developed. Reliability aspects related to the barriers are integrated into the calculations.
