VeMoLahn

Interaction of vegetation and morphodynamics in brushwood groyne fields

The research project is funded within the framework of the BMBF funding announcement of 7th June 2021: "Entwicklung von nachhaltigen Lösungen im Küsten- und Hochwasserschutz sowie der Unterhaltung von Wasserstraßen und Häfen".
The salt marshes fronting dykes that are regularly flooded and affected by storm surges, play a central role in the preventive coastal protection along the North Sea coast. A key function of salt marshes is their ability to adapt to a certain extent to changing sea levels through lateral and vertical growth dynamics. Whether foreshores growth can keep pace with accelerated sea level rise in the future, however, depends strongly on local currents and the sediment budget regularly introduced by the tides and storm surges. Brushwood groynes can support critical accretion processes as they offer a hydrodynamically calmed settlement space and at the same time support the colonisation and thus consolidation of the tidal flats by salt-tolerant pioneer plants. The overarching goal of the research project is to provide coastal protection authorities and municipal planning authorities with tools in the form of numerical models. Such models will enable a well-founded projection of the effects of structural changes, maintenance measures and climate-related changes in sea level on sedimentation and vertical growth processes in brushwood groyne fields.
For this purpose, the knowledge gaps on sedimentation and erosion processes in brushwood groyne fields, which depend on wave energy, sea state, vegetation cover and structure as well as the design and the structural composition of the brushwood groyne fields are to be analysed. Based on these findings, the hydro-morphological and biological parameters will be quantified and integrated into the model systems.

• VeMoLahn-A

  Spatial distribution of vegetation and sea state in brushwood groyne fields

  BMBF funding code	03F0929A
  Duration of funding	01.11.2022–31.10.2025
  Project partner(s)	Technische Universität Braunschweig, Leichtweiß-Institut für Wasserbau Dr.-Ing. Oliver Lojek

  The Technische Universität Braunschweig will record the directional sea state on the East Frisian and North Frisian coasts in two selected brushwood groyne fields in order to measure and quantify the transformation of the incoming waves depending on their incident direction. In addition, 2D experiments will be conducted in a physical wave flume to investigate the influence of wall geometry and transparency of brushwood groynes. The data obtained will be incorporated into 3D numerical models, which will be used to investigate potential optimisation, construction and maintenance measures in preventive coastal protection.

• VeMoLahn-B

  Spatial Distribution Patterns

  BMBF funding code	03F0929B
  Duration of funding	01.11.2022–31.10.2025
  Project partner(s)	Leibniz Universität Hannover - Fakultät für Bauingenieurwesen und Geodäsie, Ludwig-Franzius-Institut für Wasserbau, Ästuar- und Küsteningenieurwesen Dr. Maike Paul

  The Leibniz Universität Hannover will investigate the interaction between hydro-, morpho- and vegetation dynamics in brushwood groyne fields. This sub-project primarily aims to investigate and, if necessary, optimise the geometry of the brushwood groynes in order to promote the growth of the foreshore and its colonisation and stabilisation by salt marsh plants on the basis of natural processes. For this purpose, various brushwood groyne fields along the German North Sea coast are to be mapped using remote sensing methods. Beyond that, the links between hydrodynamics and seasonal suspended sediment concentrations in the water column as a function of vegetation cover are to be determined within the framework of field campaigns.