Methods and Analysis Tools for Redevelopments in an Estuary With High Suspended Sediment Concentrations

One of the largest estuaries in Germany, the Ems estuary, identified a dramatic turbidity increase up to more than 10 g/l over the last years. Due to this fact ecologists and water management authorities try to find restoration measures, which are able to reduce suspended sediment concentrations and to increase oxygen supply. The assessment of these potential restoration measures is described in the following paper and is based on a highly resolved numerical representation of the present situation of the Ems with extreme high turbidities by including effects of flocculation and hindered settling. Therefore two different approaches for the settling velocity due to flocculation were compared. An analysis of these restoration measures delivers important findings and shortcomings of each measure. Finally the restoration potentials are quantified by key indicators for hydrodynamics and suspended sediment transport behavior and were evaluated due to their relevance in reduction of high turbidities.