Modelling of bar dynamics

Within the VOP Project, RIKZ of Rijkswaterstaat and WL | Delft Hydraulics are collaborating on the development/improvement, validation and assessment of morphodynamic models. Last years, much effort has been assent to the improvement of DELFT3D ? Online model, based on the engineering sand transport formulations of TRANSPOR2004 model (Van Rijn, 2006-a and ?b). The most important improvements involved the refinement of the predictors for the bed roughness and for the suspended sediment size. Consequently, it was necessary to recalibrate the reference concentration of the suspended sediment concentration profile. More recently, the attention was focussed on the development of a general bed load transport equation that can be used for both steady and oscillatory flows, using the concept of instantaneous bed shear stress. This equation includes both wave-related and currentrelated components, with a numerical intra-wave approach. Proper predictive modelling of the wave-related oscillating transport components requires an accurate description of the near-bed orbital fluid velocity, especially in conditions of non linear wave motion. To that end, the method of Isobe-Horikawa (1982) modified by Grasmeijer (2002) is used. Besides, the suspended transport is computed as the sum of the current-related transport of sediment by the mean current, including the effect of wave stirring on the sediment load, and of the wave-related transport, resulting of the asymmetric oscillatory wave motion near the bed in shoaling waves (based on the method of Isobe-Horikawa, 1982).