An efficient method to assess erosion risks in tidal basins

Predicting erosion of channel banks and tidal flats due to wind waves in tidal basins involves multiple parameters. These parameters represent the hydrodynamic load onto a bank as well as the stability of a bank against erosion. An efficient method to predict bank erosion in tidal basins is by calculating the sediment stability parameter based on the initiation of motion of sediment particles, because this parameter includes both the oscillatory bed stress and the sediment characteristics. The loading by wind waves on banks and tidal flats can be quantified by the bed shear stress. Wave breaking can be quantified by means of the in tensity parameter of energy dissipation by wave breaking. Calculation of the sediment stability parameter gives insight in the sedimentation may occur in the future. Aa a case study, the future reintroduction of the tide in Lake Grevelingen, in the Netherlands, is studied. The reintroduction of the tide may be combined with a tidal power plant in the Brouwersdam, between the North Sea and Lake Grevelingen. Reintroduction of the tide will change the wave load on intertidal areas in Lake Grevelingen. The effects of a tidal power plant in the Brouwersdam on erosion and the effectiveness of bank protection in Lake Grevelingen are analysed. The results of this morrphological analysis are used as input for an environmental impact assessment. This case study shows that studying the initiation of mottion is an efficient method to assess the local risks of (bank) erosion.