Hydraulic boundary conditions

In the design of the Oosterschelde storm surge barrier semi-probabilistic methods have been used. the probabilistic load calculation requires knowledge of the three dimensional probability density function of storm surge level,basin leveland wave energy. However especially in the interesting regions of low probability of occurence the consequent,lack of measured data prevents a reliable estimate oft his function. In this paper a combination of purely statistical models and mathematical models, based on physical law sand checked with measured data,has been used. the probability density function of the storm surge level is based on a purely statistical model. A simplemathematical model,based on physical facts,is used to derive the conditional probability density function of the basin level on the storm surge level. the conditional probability density function of the wave energy on the storm surge level is found along the same lines. A mathematical model is developed based on the hypothesis, that the typical double peaked form of the wave spectrum is caused by the fact, that the wave energy originates from two sources. Waves,entering the estuary from deepwater via the shoals and waves,generated locally,from together the sea stateat the barriersite. the required three dimensional probability density function of storm surge level,basin level and wave energy is derived as the product of the probability density functions referred to above.