A_wijdeveld_ M_ Wensveen.mp4

Recording of presentations at the Suricates project closing conference

Title :Use of rare earth elements and optical cable to quantify the sedimentation from different sediment sources in Port of Rotterdam (The Netherlands)

Arjan WIJDEVELD*1, Marco WENSVEEN2 1 Deltares, Daltonlaan 600, 3584 BK Utrecht (Netherlands) 2 Port of Rotterdam, Wilhelminakade 909, 3072 AP Rotterdam (Netherlands) * Corresponding author e-mail: arjan.wijdeveld@deltares.nl

Summary :

For the INTERREG SURTICATES pilot in Port of Rotterdam 580.000 m3 (220.000 tons) of sediment was reallocated within the port to increase the resilience of the riverbank and a constructed wetland (sediment nourishment).

The challenge is to quantify the impact of the sediment nourishment on the target sites and at the same time establish the impact the sediment nourishment on other areas in the port (including the shipping lanes and docks). The total yearly dredged sediment budget for the port during the pilot is around 10 mln. m3 of sediment, the pilot therefore is only 6% of the yearly sediment budget.

By installing optical cables along the pilot site, both in parallel with the riverbank/wetland and across the navigation channel and within the wetland the coverage of the cables could be tracked by using the difference in water temperature during the tidal shift. If the cable is covered with sediment it takes longer to transfer heat towards the cable, hence a slower shift in the bottom water temperature due to the tidal salt-/freshwater interchange can be used to establish the sedimentation pattern.

The optical cables work for establishing the near field and mid field (up to 2 km) sedimentation impact of the pilot. For far field (20 km up- and downstream) we used the unique Lanthanum (La) addition in the dredged sediments. By taking grab samples and establishing the rare earth ratio in relation to La (also a rare earth) the contribution of the dredged sediments on the total system sediment budget can be established.

By using optical cable measurements, rare earth elements and bathymetry measurements we derived that the total sediment budget in the port was increased with +0.2% by the pilot. Unfortunately, this additional sediment did not go to the riverbank or wetland.

Acknowledgements: The SURICATES project is funded by the European Regional Development Fund (ERDF) as part of the Interreg NWE programme 2014-2020.