Bouma, T.

Gourgue, O.

Meire, P.

Schwarz, C.

Temmerman, S.

van Belzen, J.

Van de Koppel, J.

Open Marine Archive

46    ECSA Local Meeting 2016   
 
Forecasting the biogeomorphic development of intertidal 
wetland restoration: a novel modelling approach 
Christian Schwarz1, Jim van Belzen2, Olivier Gourgue1, Tjeerd Bouma2, Johan van de Koppel2, Patrick 
Meire1 and Stijn Temmerman1 
1 University of Antwerpen, Ecosystem Management Research Group, Wilrijk, Belgium  
 E-mail: christian.schwarz@uantwerpen.be   
2 NIOZ Royal Netherlands Institute for Sea Research, Department of Estuarine and Delta Systems, 
and Utrecht University, The Netherlands 
 
Managed realignments - i.e. the landward displacement of seawalls in order to create new intertidal 
habitats on formerly embanked land - are becoming an important engineering option enabling the 
reduction of the costs of coastal defenses, providing a sustainable approach in dealing with sea 
level rise and simultaneously delivering environmental benefits through the creation of intertidal 
habitats. A major challenge in managing, planning and executing managed realignments lies in 
optimizing their design in respect to abiotic factors (e.g. dimensions of dike breaches or of channel 
networks) and biotic factors (e.g. revegetation or natural establishment of plants) in order to 
guarantee success within the desired time frame. Due to the novelty of this approach and the lack 
of long-term data available, numerical models are applied to breach this gap. 
 
We use a coupled finite element hydrodynamic- (TELEMAC2D), morphodynamic- (SISYPHE) and an in-
house developed vegetation growth model, in combination with field experiments and 
measurements, to forecast the development of a future managed realignment site over a period of 
several decades (465 ha, Hedwige-Prosperpolder, Scheldt estuary, Belgium & The Netherlands).  
 
The novelty of our approach resides in the subgrid/mesh approach which is used in modelling 
spatio-temporal vegetation development. This approach allows us to take small scale (e.g. 0.25m) 
interactions between vegetation, flow and sediment transport into account although the hydro-
geomorphic model is run on a coarser gird (e.g. 5m). It not only reduces computational time, opens 
possibilities for sensitivity testing, but potentially conserves the importance of small scale 
vegetation dynamics on shaping landscape patterns such as the erosion of channels. 
 
This study summarizes the vegetation and sedimentation parameterization, and discusses 
preliminary results in the context of large-scale (100s of ha) biogeomorphologic development for 
long-term (decades) forecasting and its management implications. 
 
  


Forecasting the biogeomorphic development of intertidal wetland restoration: a novel modelling approach

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