Harbor-Entrainment Due to Complex Tidal Flow Patterns
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Wurpts
Abstract: International seaports accessible for today’s big ships are often located at estuaries where the hydrodynamic situation can be strongly influenced by density effects like vertical gravitational circulation. The present paper deals with the hydrodynamic situation of one harbor entrance of the seaport of Bremerhaven. The port is located near the upstream end of the Weser-estuary at the German North Sea coast and suffers from increased sedimentation of fine silty sediment which forms layers of fluid mud in the tidal basin. The sediment is entrained from river Weser by complex flow patterns. Also the fluid mud is entrained into the inner tide-free harbor during lock operation. This contribution deals with the application of a three dimensional morphodynamic numerical simulation model. As a first step the hydrodynamic situation was reproduced in order to do morphodynamic runs later. Due to the influence of density driven flows the transport of dissolved salt was also calculated. Detailed ADCP measurements of flow velocity and direction as well as salinity measurements were available for the port entrance. The local hydrodynamic situation at river Weser is highly transient and dominated by tidal movement and barocline stratification. The flow measurements show distinct interaction of several flow-effects like recirculation, tidal filling and emptying of the harbor basin and density effects at the same time and different depths. This complex situation is taken as a validation case for a three dimensional SMOR3D simulation model, which was extended in order to consider densitydepending damping of turbulent momentum exchange. The model can help to improve strategies to minimize the entrainment of sediment into harbor basins under complex hydrodynamic situations in order to reduce dredging– related maintenance costs.
Keywords: Numerical modeling, estuary, density stratification, fluid mud