High turbidity zones are common phenomena in tidal estuaries. Suspended 
particulate material (SPM), which causes the turbidity, is accumulated at the 
landward side of the salt intrusion and also in places in the freshwater region. 
Accumulations in the tidal River Elbe are reproduced with a three-dimensional 
Lagrangian model for the transport, deposition and resuspension of SPM.

Subject of this paper are accumulations in the freshwater region. Different 
approaches to determine residual currents are applied out in order to identify 
current structures that are related to SPM accumulations. Classical approaches 
of describing Lagrangian residuals result in convergence in the mixing region in 
the waterway. They give no indication on accumulations in regions without 
density stratification. Eddies close to areas of high SPM concentrations are 
found when the analysis takes into account horizontal gradients of current 
properties.