A first phase in the habitat classification for the Sea Scheldt : Bed Form Classification.

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Gwendy Vos, Yves Plancke, Tatiana Maximova

Monday 29 june 2015

12:15 - 12:30h at South America (level 0)

Themes: (T) Special session, (ST) Scheldt Estuary physics and integrated management

Parallel session: 1J. Special session: Scheldt Estuary physics and integrated management

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Within the scope of the long term vision of the Scheldt estuary and the Development Outline 2010 low dynamic intertidal and shallow water areas are considered to be of high ecological value. These areas are in fact linked to eutrophic foraging zones for birds and young fish and to refugees for tidal migrators. However, this assumption is based on experiences in other areas and there is no evidence that all parts of the shallow water area are equally valuable. Little is known about the occurrence of such valuable areas in the Scheldt estuary, nor are the physical and morphological processes which determine the occurrence of these areas fully understood. Following research on this topic on the area near the Walsoorden Sandbar in the Western Scheldt (the Netherlands) in 2008-2009, a new research project was defined to determine relationships between physical, sedimentological and ecological characteristics in the Sea Scheldt (Belgium) and to set up a classification of undeep subtidal and intertidal areas. A first step in the habitat classification comprised of a detailed analysis of 5 sub areas, each characteristic for a certain salinity zone. The first phase of the analysis of the subareas consisted of an analysis of multibeam echo sounding data in respect to the occurrence of bed forms, which resulted in a classification of each sub area in a limited amount of bed form classes. In a second phase a numerical hydrodynamic model was used to determine hydrodynamic characteristics for each of the subareas. Based on the results of the first two phases, accordance between hydrodynamic and physical characteristics was sought, but none could be found. However more insight was obtained about the range of bedform sizes and the configuration of hydrodynamic zones. In a last phase data from the first two steps will be combined with ecological parameters to try and find relationships and develop a map of the spatial variation of the ecological value for the different sub areas.