Sediment dynamics and geomorphic changes in tidal marshes
Temmerman, S.; Govers, G.; Wartel, S.; Meire, P. (2002). Sediment dynamics and geomorphic changes in tidal marshes, in: ECSA Local Meeting: ecological structures and functions in the Scheldt Estuary: from past to future, Antwerp, Belgium October 7-10, 2002: abstract book. pp. 19 In: (2002). ECSA Local Meeting: Ecological structures and functions in the Scheldt Estuary: from past to future, Antwerp, Belgium October 7-10, 2002: abstract book. University of Antwerp: Antwerp. 73 + 1 cd-rom pp., more |
| Available in | Authors | | Document type: Conference paper
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| Keywords | Earth sciences > Geology > Geomorphology
Equilibrium
Particulates > Suspended particulate matter
Sedimentation
Temporal variations
Topographic features > Landforms > Coastal landforms > Tidal flats
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| Abstract | Tidal marshes act as net sinks of sediment, which leads, in the long-term, to geomorphic and ecological changes of marshes and estuaries. Tidal marsh sedimentation is studied in the Scheldt estuary on different spatial and temporal scales. On the small-scale (10-100 m and 1 tide to 1 year), field measurements show that temporal variations are controlled by a positive linear relationship between incoming suspended sediment concentration (SSC), at the beginning of marsh flooding, and maximum inundation height, at high tide. The spatial sedimentation pattern is determined by three parameters: elevation of the marsh surface, distance to the nearest tidal creek, and distance, along this creek, to the marsh edge. The long-term (10-100 years) implications of these sediment dynamics were investigated using a physically-based numerical model, which takes the observed increase of incoming SSC with maximum inundation height into account. The modelling results, which are in good agreement with observed long-term accumulation rates, show how young low marshes accumulate much faster than old high marshes and how both tend to the same equilibrium elevation. This explains the generally flat topography of tidal marshes. The model also simulates the fast formation of natural levees along tidal creeks, and also here a geomorphic equilibrium exists: once levees grow 20 to 30 cm higher than inner marsh basins, which are located farther away from tidal creeks, the influence of distance to the tidal creek is compensated by the influence of surface elevation, so that levees and lower marsh basins accumulate at the same rate. |
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