Modelling the deposition, erosion, and flux of cohesive sediment through Øresund

Øresund is a narrow sound between Denmark and Sweden in Northern Europe. The sound has a complex hydrography with two- or three-layer stratifications, sometimes with opposite directed currents in the different layers. The complicated hydrography makes it difficult to investigate sediment dynamics by use of traditional field-work based methods. In this study the three-dimensional modelling system MIKE 3 was applied in order to quantify the dynamics of the fine-grained sediment in Øresund over a year. The model simulated the complex hydrodynamics including stratification satisfactorily. The simulated suspended sediment concentrations were low, generally not exceeding 20 mg l−1. Over the year 2000 the model computed an annual accumulation of 136,000 tons of sediment. Both the sediment concentrations and the overall accumulation of fine-grained sediment are in accordance with previously published results. This study presents some general hydrodynamic and sedimentological characteristics from the sound. The hydrodynamic characteristics were well reproduced, making the hydrodynamic model ideal for the sediment transport study. The description of the sedimentology of the sound is in some aspects new and is therefore not directly verified by data. The overall result is believed to be representative for the area and the model has given information on sedimentological transport patterns. This study demonstrated that generic numerical cohesive sediment transport models are capable of simulating hydrodynamics and cohesive sediment dynamics in complicated estuarine environments and of establishing reliable sediment budgets.