The Rhine-Meuse estuary is part of the Southwestern Delta area in the Netherlands. The nature present in the estuary suffered a great impact due to urbanization, as a natural delta transformed into an industrialized river, mainly due to port activities. Various parties decided to
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The Rhine-Meuse estuary is part of the Southwestern Delta area in the Netherlands. The nature present in the estuary suffered a great impact due to urbanization, as a natural delta transformed into an industrialized river, mainly due to port activities. Various parties decided to collaborate in order to return the tidal nature in the Rhine Meuse estuary through constructing tidal parks. Although the idea of reintroducing tidal nature into an industrialized estuary seems promising, problems arise when the projects are being executed. Human interventions necessary to complete the design of the tidal parks often lead to undesired morphological changes. These either consisted of an excessive amount of cohesive sediment import, or hardly any import. Consequently, maintenance in form of dredging or nourishing activities is required. When introducing tidal nature, little maintenance is desired, both from a financial perspective and from an ecological perspective. The undesired morphological changes result from limited knowledge on the impact of human interventions on the hydro and morphodynamics in tidal parks. This research therefore primarily focuses on gaining new knowledge on the hydrodynamics and morphodynamics inside tidal parks and assessing the effect of different elements such as groynes and longitudinal walls on the latter. This is done through a case study, the Groene Poort, a collective name for the tidal parks located in the Nieuwe Waterweg.
A depth-averaged (2DH) Delft3D model is used to research the hydro and morphodynamics of the tidal park. A constant tidal forcing and a constant fresh water discharge are used as boundary conditions. The effects of wind, waves and density driven currents are neglected. The effects of changes in hydrodynamic forcing, including a morphological tide, a spring tide and a spring tide in combination with a surge on the morphodynamics are determined. This research showed that the tidal flow results in relatively small velocities inside the studied tidal park with mean velocities around 5 cm/s. The critical velocities for transport of noncohesive sediment transport are only reached at the west entrance of the studied tidal park. At this location the sediment deposits, further transport towards the river bank is not possible resulting from the magnitude of velocities. A spring tide is responsible for an increased import of noncohesive sediment at the river bank area.
This research provides a guide on the effect of relatively small adaptations in geometry which will enhance or decrease the natural processes of sedimentation and erosion in the tidal parks. Tables are included providing the important parameters both with respect to the hydro and morphodynamics of various adaptations in geometry. These tables can be used in future design and adaptations of already constructed tidal parks. However, the effect of the surrounding area including the location in the river greatly impact the hydrodynamics and morphological development of the tidal parks.