A 2.5D Model for Sand Transport in a Shallow Sea: Effect of Ekman Veering

A process-based sediment transport model is presented that combines the knowledge of sediment transport in rivers and estuaries with the understanding of physical processes specific for the shelf seas. Due to formation of bottom Ekman spiral, the near-bottom current and hence the sediment transport deviate from the direction of surface current. The model takes into account velocity veering induced by Ekman spiral and estimates both direction and rate of transport of suspended particulate matter (SPM) generated by a steady or slowly varying current, through suspension, relocation and deposition of sediment in a shallow sea. The model uses a combination of analytical and numerical methods: analytical integration, in the vertical, and numerical integration, in the horizontal. The model predicts also vertical erosion/deposition fluxes at the seabed. The deviation angles and other parameters of SPM transport are computed for a range of water depths 5-50 m, particle settling velocities 0.1-6 cm/s, and current speeds 0.4-1.2 m/s. The model converges automatically to traditional engineering-style formulations, in extreme case of strong current in very shallow water, where velocity veering is of minor importance.