Fluid mud can be described as a high concentrated aqueous mixture of fine-grained sediment and organic material (McAnally et al. 2007). In reservoirs where siltation occurs, fluid mud layers can be observed (White 2001). This results in increasing maintenance costs for the reservoir management and has to be considered within different sediment removal operations (van Rijn 2013). During the transport of suspended cohesive sediment, density induced vertical stratification effects occur. Differently concentrated vertical layers can be defined over water depth (Winterwerp & Van Kesteren 2004). The viscous, Newtonian behavior of low concentrated suspensions can be described by turbulence models and the viscoelastic, non-Newtonian behavior of fluid mud by rheological models (Malcherek & Cha 2011, Wehr 2012). However, to characterize the dynamics of muddy reservoirs a continuous modelling approach from damped to free turbulence in suspensions is necessary (Roland et al. 2012). This approach is implemented in an implicit, in stationary and fully coupled 1DV-model. The model solves the one-dimensional momentum equation together with the transport equation for suspended matter and a modified two-equation k—ε turbulence model. To account for the rheological viscosity in the fluid mud layer, the viscosity in the momentum equation is modified as the sum of the turbulent and the rheological viscosity, see Equation 1. (1) ν e f f = ν t + ν r h https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315623207/4fbc492d-6678-4a12-aaf6-5c2b8ea38e5f/content/eq1197.tif"/>