PhD Position Understanding Sediment Dynamics for Equilibrium-Based Dredging Strategies in Ports

Maintenance dredging of sediment deposits can be highly expensive and inefficient. Port operators seek tailor-made solutions to reduce the costs and at the same time guarantee safe navigation. Over the last decades, a number of strategies for port maintenance have been tested by port and governmental authorities.  Conditioning the sediment is a possible solution for port maintenance. The goal of conditioning the sediment is to reduce its strength in order to create navigable conditions (fluid mud layers) while keeping the sediment in place, for example by re-circulation of the sediment. If the transport of fluid mud (out of a port towards the river or the sea) equals the import of suspended mud by exchange flows, a dynamic equilibrium is achieved without residual import, making conventional dredging and relocation unnecessary.

The main objective of this research is to develop new knowledge on conditioning for port maintenance  dredging in the Seaport Emden, Germany. Field and laboratory studies will be conducted aiming at keeping the sediment properties below the nautical criteria for nautical bottom applications. In-situ analysis of key sediment characteristics (density, rheological properties, bathymetry, turbidity, organic matter reactivity, oxygen saturation, etc.) will be conducted in order to optimize the maintenance efficiency and to relate the effect of the maintenance to the short-term and long-term changes in the system.

The second objective of the study is to reproduce the abovementioned dredging methods in the laboratory and study the effect of the methods on the sediment properties. Particularly,  the impact of sediment conditioning on rheology, structural recovery, settling, consolidation, mineral composition, oxygen saturation, redox potential, pH and stability of organic matter will be studied.

This research will develop knowledge for designing circular strategies in ports. Furthermore it will collect evidence to what extent current strategies comply with circularity principles. The developed framework will be serving as a decision making tool facilitating the analysis of the sediment maintenance strategy and required maintenance depth.