MorphoWeser - Dynamic of cohesive sediments

The Project “Event based morph dynamics in the Weser Estuary – Study of dynamics of cohesive sediments in the Weser within the reach of Blexer Bodgen and Nordenham” is carried out in cooperation with the Federal Waterways Engineering and Research Institute (Bundesanstalt für Wasserbau, BAW). It is part of the research project “Event based morph dynamics in the Wester Estuary (MorphoWeser)“.
The focus of the sub-project lies on the transport of the cohesive sediment fractions in the Weser estuary.

To provide save shipping conditions in the navigation channel in the Weser estuary maintenance dredging has to be applied within the frame of sediment management of the Federal Waterways and Shipping Administration   (Wasser- und Schifffahrtsverwaltung, WSV). A core area for dredging is located between Weser km 55 – 65 (named “Blexer Bogen” and “Schlickstrecke Nordenham”; see  figure below). In this reach predominately fine,   cohesive sediments deposit with a high organic load. Dredged volume reaches approx. 1-2 Mio. qm a year. To optimize the sediment management of the WSV and to predict the implications of future hydraulic engineering   measures it is necessary to be able to simulate the actual natural sediment dynamics in this area. This requires an adaptation and extension of existing models.
Furthermore, a fundamental interest is given to get a better understanding of the natural processes in the Weser estuary, influencing the hydro- and morphodynamics. A high importance is ascribed to the specific properties and effects of cohesive sediments in this context

1. State of the scientific and technical knowledge

• Modelling transport behaviour of cohesive sediments
• Specific studies about the Weser estuary
• Relevant research demand
• Possible model adaptations and extensions

2. Modelling of abiotic sediment transport (state of technology)

• Simulation of specific processes
  • Estuarine circulation
  • Tidal pumping
  • Formation of the estuarine turbidity maximum (ETM)
• Reproduction of net-deposition areas

3. Improvement of current formulations for sediment transport

• Detailed description of (effective) settling velocity
• Enhanced bed exchange model

 D-Flow and D-Morphology of the DELFT3D-Suite, an open source modelling environment of Deltares, are used. The model domain is defined according to the following figure.

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