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impact of vegetation on flow routing and sedimentation patterns : three-dimensional modeling for a tidal marsh

Temmerman, S. and Bouma, T.J. and Vries De, M.B. and Wang, Z.B. and Govers, G. and Herman, P.M.J. (2005) impact of vegetation on flow routing and sedimentation patterns : three-dimensional modeling for a tidal marsh. Journal of Geophysical Research, 110, F04019-. ISSN 0148-0227.

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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. [KEYWORDS: hydrodynamic modeling ; sediment transport ; wetlands ; floodplain dynamics ; riparian systems]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11795
Deposited On:23 Nov 2011 01:00
Last Modified:09 Jan 2014 14:59

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