Today's sea dykes are around 8.5 metres high and require a dyke foot width of around 100 metres. If the dikes have to be raised due to sea level rise, they also have to be wider (to maintain the slope and stability), so the area required for a dike is enormous. (write more about this?)

The base of the dyke therefore needs more space in order to be adapted to climate change. In addition, the materials for dyke construction (bran, sand, possibly stones) have to be sourced from somewhere.

Literature: General plan for coastal protection: www.schleswig-holstein.de/DE/fachinhalte/K/kuestenschutz/Downloads/Generalplan.pdf