Zuiderzee is now called IJsselmeer*: Process-based modeling

Constructing a closured am such as Afsluitdijk causes an instantaneous change in tidal wave propagation and flow field in the basin which triggers extensive morphological changes in the adjacent tidal basin. These morphological changes may continue for centuries before the whole system reaches a new "equilibrium" state, which is different from the "equilibrium" in case the closure would not have been done. In this paper we have used Delft3D to investigate the characteristics and time scale of the morphodynamic effects of construction of the Afsluitdijk. In this research we focused on tidal forces only. A schematized bathymetry with a uniform depth is used in the model with the land boundary of Waddenzee before the closure. A morphological simulation is carried out for 4000 years. Using this procedure ensures us that the morphological "equilibrium" state which is reached in this simulation is only due to the tidal forcing. In subsequent runs we have applied a closure after 1000, 2000 and 3000 years and continued the simulation while the closure dam was included in the model. The main outcome of this research is that as soon as the closure is applied the sediment transport regime of the basins changes from exporting to importing, which corresponds with the existing hypothesis based on measurements at Marsdiep.