PREVENTION OF SEDIMENTATION IN BRACKISH WATER HARBOURS

摘要

The paper will discuss influences causing the formation of fluid-mud in brackish harbour basins. In general, fluid-mud consists of very fine sediments (silt and clay) with a high organic content. Also it has low density and viscosity. The analysis of dual frequency echo soundings (210 kHz and 15 kHz) will demonstrate that the fluid-mud volumes in the outer harbours of Emden, Bremerhaven and Brunsbuttel are nearly constant over a period of years. The key for the creation of fluid-mud is the presence of a bar at the harbour entrances. Innovative measures to prevent sedimentation will be discussed. The methods are KSN: Keep Sediment Navigable or KSO: Keep Sediment Out. The KSN strategy takes advantage of the ability of ships to sail through fluid-mud by maintaining the aerobic conditions in the fluid-mud layer with the supply of oxygen. This can be achieved by selective dredging methods or water injections. The KSO method will consider the possibility of establishing a bottom slope away from the sea-lock towards the harbour entrance.