– We are working on a business case to lay out artificial reefs at Hyldtofte, downstream from the work harbor. This could hopefully reduce the need for beach nourishment.
These were the words of Oliver Ries, team leader for the environmental department at Sund & Bælt, during a recent conference on sustainable construction held by Erhvervsfyrtårn Femern.
He spoke after Per Goltermann, a professor at DTU, gave a presentation on artificial reefs.
– On the southern side of Lolland, there’s plenty of erosion. So, people use beach nourishment, but that’s like wetting your pants to stay warm. It works if you do it every year,” he said, outlining a better solution: building artificial reefs.
– Beach nourishment is like wetting your pants to stay warm. Erosion can be halted by placing stones,” he said, explaining that plans are in place to construct three artificial reefs off the southern coast of Lolland.
Washed for pesticides
This type of solution has, on one hand, state support, with plans to invest half a billion kroner in a project to restore coastal stone reefs. On the other hand, it can be challenging to get the necessary permits to actually carry out the work.
– Many municipalities are interested in establishing artificial reefs. But the Coastal Directorate decides whether you’re allowed to lay out an artificial reef, and they mostly only permit it if it’s for research or educational purposes, he said, adding that it’s usually easier to get approval for restoring stone reefs using glacial stones.
These are natural stones from the Ice Age, typically round fieldstones that are washed for pesticides and then laid on the seabed.
Analyses underway
It is possible to get permission, and researchers are working on designing the most optimal reefs, which can not only help protect the coast from erosion but also increase fish populations. The work involves creating spaces where fish can spawn, and where larvae, small fish, and larger fish can live—and hide from crabs.
Oliver Ries from Sund & Bælt mentioned that the project along the South Lolland coast plans to use both river stones, blasted rock, and leftover concrete from tunnel elements.
We are in the process of conducting analyses to determine how it will affect sediment flow, he said.
