The mud deposits and the high turbidity in the Belgian–Dutch coastal zone, southern bight of the North Sea

The suspended sediment processes and the mudfields found in the Belgian/Dutch coastal area (Southern North Sea) are discussed by presenting an integrated data-modelling approach of the suspended sediment transport along the Belgian–Dutch coast, using a fine-grid coupled 2D hydrodynamic and sediment transport model and existing field and literature data. These mudfields and turbidity maxima are situated in a well-mixed, highly energetic hydrodynamic environment. In the past the occurrence of this high turbidity zone (more than a few hundreds mg/l of suspended matter) was ascribed to a closed hydrodynamic system (gyre) in front of the coast. This study shows that the SPM input through the Strait of Dover, the shallowness of the considered area, the decreasing magnitude of the residual transport vectors from the French/Belgian border towards Zeebrugge and the specific hydrodynamic features are the main processes responsible for the presence of the turbidity maximum. The origin and the formation of these mud deposits in front of the coast are explained by the neap-spring tidal cycles and the presence of SPM sources (import of SPM through the Strait of Dover and through erosion of clay layers).