Sedimentological research as a basis for environmental management: The Øresund fixed link

A fixed 16 km link immersed tunnel, artificial island and peninsula, bridges. to connect the Scandinavian countries of Denmark and Sweden is being constructed during the period 1995]2000. The link crosses Øresund, one of the three sounds connecting the brackish Baltic Sea to the oceanic North Sea. Dredging of approximately 8=106 m3 of limestone bedrock and clay till is being carried out during the construction phase. Environmental planning and management when constructing the fixed link were heavily dependent on extensive sedimentological and biological research prior to construction. Base-line turbidity and seabed sediments were investigated, and sediment spill parameters were measured during test dredging and test reclamation, in addition to the environmental impact. Now, when dredging and reclamation have been finalised in Øresund, it is clear that the environmental management approach used during construction of the fixed link has safeguarded the marine environment in Øresund. At the same time it has allowed the dredging and reclamation works to be carried out within the planned time period and expenses. A detailed base-line monitoring of the regional turbidity regime and the regional sedimentation regime in Øresund made post-dredging evaluation of the regional effects possible. The measurements in Øresund showed that the construction caused no permanent regional change in turbidity and sedimentation, as the base-line conditions did not change.