Non-uniform modelling of suspended sediment transport in the Tagus estuary

Laboratory tests with fine sediment from the Tagus estuary (Portugal) indicate that a non-uniform description of suspended sediment transport is physically more realistic than a uniform description. A two-dimensional horizontal model, considering a single sediment class and multiple sediment classes, is used to simulate the transport of suspended sediment in the Tagus estuary. The two modelling alternatives produce similar results, but the multiple class approach appears more suited to simulate phenomena that are not well described by the average sediment. The computing time increases with the number of sediment classes and sediment classes with lower than average settling velocities require longer than average periods of simulation to reach equilibrium.