Early Warning Systems (EWS) are nowadays becoming fairly standard in river flood forecasting or in large scale hydro-meteorological predictions. For complex coastal morphodynamic problems or in the vicinity of complex coastal structures, such as harbours, EWS are much less used because they are both technically and computationally still very challenging. To advance beyond the state-of-the-art, the EU FP7 project RISC-KIT (www.risc-kit.eu) is developing prototype EWS which address specifically these topics. This paper describes the prototype EWS which has been developed for the case study site of the harbour of Zeebrugge, situated in Flanders along the Belgian coast, allowing the validation of the newly developed tools. The challenge for this EWS and DSS (Decision Support System) is selecting the right number, type, and detail of the models in order to get a sufficiently detailed and trustable results, while keeping calculation time limited in order to allow fast and frequent predictions. In general, waves inside harbours are a combination of locally generated wind waves and offshore wave penetration at the port entrance. Outside a prediction environment, the conditions inside the harbour could be assessed by superimposing processes. The assessment can be carried out by using a combination of a spectral wave model (i.e. SWAN) for the wind generated waves and a Boussinesq type wave model (i.e. Mike 21 BW) for the offshore wave penetration. Finally, a 2D hydrodynamic model (i.e. TELEMAC) can be used to simulate the overland flooding inside the port facilities. To reproduce these processes under a EWS environment, an additional challenge is to cope with the limitations of the calculation times. This is especially true with the Boussinesq model. A model train that integrates process based modelling, for wind generated waves, with a smart simplification of the Boussinesq model for the wave penetration effects, is proposed. These wave conditions together with the extreme water levels (including storm surge) can then be used to simulate the overtopping/overflow behaviour for the quays. Finally, the hydrodynamic model TELEMAC is run for the inundations inside the port facilities. The complete model train was integrated into the Deltares Delft-FEWS software for scenario simulating to showcase the potential for real time operations. |
