A Numerical Model for Fluid Mud Dynamics in Estuarine Systems - Overview and Outlook

摘要

Fluid mud is a mixture of fine, mainly cohesive sediments, water and organic substances. The rheological behaviour of fluid mud is that of a non-Newtonian fluid; fluid mud is thus subject to its own dynamic compared to a water body with low suspended matter concentration. The occurrence of fluid mud in estuaries and coastal zones may vary spatially, from a few centimetres in layer thickness to river sections with fluid mud layers which are several kilometres long. The time variability of physical processes, such as the formation, transport and dissipation of fluid mud extends from a few seconds for turbu-lent mixing to months for creeping mud layers (Mehta et al. 2014). The progressive extension and development of coastal waterways has led to an increase in siltation and the formation of fluid mud in sections of estuarine shipping channels, ports and port approaches in recent decades. The need for a better understanding and profound knowledge of fluid mud dynamics has increased and new maintenance strategies and renaturation measures now need to be developed in estuaries and existing ones optimized. Numerical simulations contribute to the evaluation of such strategies. This paper summarizes the current capabilities and performance of a newly developed three-dimensional numerical model for simulating fluid mud dynamics in estuarine systems. Further possible developments of the numerical model are presented. Important aspects are the interaction of rheology and turbulence in estuaries and the influence of biological parameters.