Abstract: Each year, dredging companies remove more than two million m3 of estuarine sediment from the Scheldt River (Belgium). This is necessary to assure access to the harbour of Antwerp. International Marine and Dredging Consultants (IMDC) advises government agencies and dredging companies to help them carry out their activities. Images of the sediment concentration are essential if accurate advice is to be given. IMDC uses this information to select new salvage locations, to estimate possible movements of sediment clouds and to calibrate sediment transport

models. To support IMDC in their activities, a service is developed in the ORMES project which provides suspended sediment maps from remote sensing images in an efficient way. Our main test site is a part of the Belgian Scheldt Estuary near Antwerp. It is chosen because of the wide ranges of sediment content and IMDC’s thorough knowledge of the river system. Here, we will present the results obtained within the ORMES project for this test site.

The dataset consisted of a series of airborne hyperspectral images obtained at different stages of the tidal cycle. Airborne hyperspectral data have a high potential for mapping the sediment concentrations in rivers or coastal waters because of its high spectral and spatial resolution. Simultaneously with the airborne campaign a field survey took place. Using these field data and the high resolution airborne data, a reliable semi-empirical algorithm has been developed to derive near-surface suspended matter maps in an operational way. The produced TSM maps showed

good agreement with known variations of the suspended sediment content over the tidal cycle : maximum turbidity around high water and gradual settling of the sediment in the succeeding slack water. A resuspension of sediment takes place at the onset of the ebb flow stage, especially at the bend-related shoals. The cross-river differences in TSM matched well the variation measured at previous field campaigns. 

Keywords:

remote sensing, Scheldt, suspended sediments