Sediment investigations connected with the building of the Øresund Bridge and Tunnel

Abstract

Before, during and after the construction of the bridge and tunnel between Sweden and Denmark 1995–2000, various sedimentological investigations were carried out. The main reason for the large focus on the sediment spill issue was the potential impact on the marine life. Sedimentological investigations carried out in connection with the building of the fixed link showed that the marine life also has a significant impact on both the natural sediment transport and on the fate of the spilled sediments.

Turbidity measurements showed that algae were the main turbidity-creating agent during the summer period. In addition, measurements showed that mussel banks were able to lower the local turbidity by up to 1 FTU due to the filtering by the mussels. This effect also significantly influenced the fate of spilled sediments caused by the construction works, as spilled sediments accumulated beneath the mussel banks.

Sediment flux measurements were used in order to measure the effect on the sediment transport regime that the creation of two artificial islands had. In addition, flux measurements in artificial pits dredged in the seabed proved useful in validation of the modelling of natural bed-load transport in Øresund.

Key words:

• dredging
• sediment
• spill
• anthropogenic impact
• measuring methods