|Impact of harbour basins on mud dynamics Scheldt estuary in the framework of LTV|
|van Kessel, T.; Vanlede, J. (2010). Impact of harbour basins on mud dynamics Scheldt estuary in the framework of LTV. Deltares: Delft. 29 pp.|
Document type: Final report|
Estuarine dynamics; Sediment transport; Three-dimensional models; ANE, Netherlands, Schelde estuary [gazetteer]; Marine; Brackish water
This report discusses the 2009 activities and results in the framework of LTV-mud. Firstly, developments of the hydrodynamic model are discussed. Secondly, developments of the mud transport model are discussed. Subsequently, the model is applied to two management issues, i.e, the impact of harbour basins at Terneuzen and Antwerp on the mud dynamics of the Scheldt estuary.
The model improvements have resulted in a better reproduction of the turbidity maximum at Antwerp and the overall mud balance of the system. The model now meets the demands defined at the start of the project in 2006. The impact of the harbours at Terneuzen on turbidity levels is small. This is caused by the relative small dumping flux (< 1 MTlyr) compared to the gross sediment flux passing through the estuary (computed at about 40 MTlyr at Vlissingen). A 3 km shift of dumping locations turns out to be favourable for siltation reduction, although the reduction remains small (1- 2%). Temporarily and locally, harbour maintenance does result in a significant increase in suspended sediment concentration at Terneuzen (> 20%), but averaged over a longer time and larger area, overall turbidity levels are hardly affected. This can be explained as sediment dumping (+ term) is balanced by harbour siltation (-term).
As the size of the harbour basins at Antwerp are larger than at Terneuzen, notably relative to the tidal fluxes of water and sediment, the impact of these basins on turbidity levels of the Scheldt is more pronounced. For example, a down-estuary shift of the dumping location of sediments from Deurganckdok results in a 40 mgll reduction of the near-surface concentration in the estuarine turbidity maximum (ETM) near Antwerp. Optimisation of dredging and dumping strategies has therefore substantial potential benefits at Antwerp.