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Impact of vegetation on flow routing and sedimentation patterns: three dimensional modeling for a tidal marsh
Temmerman, S.; Bouma, T.J.; Govers, G.; Wang, Z.B.; de Vries, M.B.; Herman, P.M.J. (2005). Impact of vegetation on flow routing and sedimentation patterns: three dimensional modeling for a tidal marsh. J. Geophys. Res. 110: F04019. dx.doi.org/10.1029/2005JF000301
In: Journal of Geophysical Research. American Geophysical Union: Richmond. ISSN 0148-0227; e-ISSN 2156-2202
Peer reviewed article  
Available in  Authors 
    Vlaams Instituut voor de Zee: Open access 125739 [ download pdf ]
Document type: Scientific report
Keywords
    Floodplains
    Modelling
    Physics > Mechanics > Fluid mechanics > Hydrodynamics
    Transport > Sediment transport
    Water bodies > Inland waters > Wetlands
    Brackish water; Fresh water
Authors  Top 
  • Temmerman, S.
  • Bouma, T.J.
  • Govers, G.
  • Wang, Z.B.
  • de Vries, M.B.
  • Herman, P.M.J.
Abstract
    A three-dimensional hydrodynamic and sediment transport model was used to study the relative impact of (1) vegetation, (2) micro-topography, and (3) water level fluctuations on the spatial flow and sedimentation patterns in a tidal marsh landscape during single inundation events. The model incorporates three-dimensional (3-D) effects of vegetation on the flow (drag and turbulence). After extensive calibration and validation against field data, the model showed that the 3-D vegetation structure is determinant for the flow and sedimentation patterns. As long as the water level is below the top of the vegetation, differences in flow resistance between vegetated and unvegetated areas result in faster flow routing over unvegetated areas, so that vegetated areas are flooded from unvegetated areas, with flow directions more or less perpendicular to the vegetation edge. At the vegetation edge, flow velocities are reduced and sediments are rapidly trapped. In contrast, in between vegetated areas, flow velocities are enhanced, resulting in reduced sedimentation or erosion. As the water level overtops the vegetation, the flow paths described above change to more large-scale sheet flow crossing both vegetated and unvegetated areas. As a result, sedimentation patterns are then spatially more homogeneous. Our results suggest that the presence of a vegetation cover is the key factor controlling the long-term geomorphic development of tidal marsh landforms, leading to the formation of (1) unvegetated tidal channels and (2) vegetated platforms with a levee-basin topography in between these channels.
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