Seiche characteristics of Rotterdam harbour

Recently, the main mechanism of the generation of seiches in the Port of Rotterdam has been identified. It comprises atmospheric convection cells that arise over the relatively warm water of the North Sea which cause fluctuations in wind speed and atmospheric pressure that can generate long waves at sea as these cells move towards the coast. The new insights have been used in this study together with recent data to make a detailed analysis of the seiche characteristics of the Rotterdam Harbour. It is found that the generating mechanism that has been identified can excite basins with different natural frequencies. The ratios of seiche amplitudes at different locations inside the harbour have been derived from measurements. Moreover, theoretical amplitude ratios have been determined, based on a parameterised excitation spectrum at the harbour mouth and computed amplification spectra. The latter had been calculated in previous studies with a numerical harbour model. The results confirm the validity of this method. Moreover, the amplitude ratio that has been used for the design of the main storm surge barrier of Rotterdam has now been confirmed to within 5%. Finally, the possibility of prediction of the occurrence of these seiche events has been studied. A prediction method based on criteria for the occurrence of convection cells has been tested in a hindeast setting. Results indicate that presently the occurrence of seiche events in the Port of Rotterdam can be predicted with high accuracy. (C) 2004 Elsevier B.V All rights reserved.