Project part-financed by the European Union (European Regional Development Fund)

The Interreg IVB North Sea Region Programme

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TIDE pilot project 2: Navigation channel near Ketelplaat – Relocation of dredged sediment to deep areas of the navigation channel

Effectiveness according to development targets of measure

Step 1: Definition of development target
This measure is a pilot study with the research objective to assess the morphological behaviour of relocated sediment to deep parts of the navigation channel as a reference for planned numerical morphological modelling. The aim of the monitoring program is to detect the migration pattern of dredged material that is relocated within deep areas of the navigation channel. It was expected that most of the relocated sediment would erode, but time scale and destination were not known. The project is successful if the eroded sediment does not accumulate at the nearby sills (Drempel van Lillo and Drempel van de Parel) and does not create an additional need for maintenance dredging. A small scale pilot was chosen to prevent any irreversible morphological changes.

Step 2: Degree of target achievement
During the relocation test, a substantial volume had disappeared and after four to five months only 35% to 40% of the material remained at the relocation areas within the navigation channel. Almost 80% of the ‘disappeared’ material was found at the Ketelplaat, adjacent to the navigation channel. The nearby sills in the navigation channel (Drempel van Lillo and Drempel van de Parel) had received almost no additional sediment after the relocation test. However, at these spots dredging activities took place during the study period.
These results were expected. A complete erosion of the relocated material out of the study area or increased sedimentation on the adjacent sills would lead to an unsuccessful evaluation of the pilot project. The aim of the pilot project was to gather data for further investigation.
The relocation test was a pilot project with a larger aim of studying if this type of relocation method could reduce tidal propagation without limiting navigation. However, no significant effects on the tidal propagation were expected, nor observed so far because of the limited scale of the pilot project. The relocation of dredged sediment to deep areas of the navigation channel was helpful to understand the behaviour of relocated sediment.

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