A number of regional elaborations are discussed below as an illustration. The report can be consulted for the other elaborations.
The Wadden Sea attracts sand and sludge takes place on the outside dyke polders along the sea dyke, sometimes a few millimeters a year. The inland dyke clay polders are relatively high and form a natural seawall for the peat polders in the hinterland. There is, however, soil subsidence due to tectonics, settling, gas extraction and salt extraction. In combination with the sea level rise, this means that the sea wall must also be strengthened along the northern coast. The coastal zone here also has to do with increasing salinisation. Due to the relatively high location, the options for freshwater supply are limited.
Three zones can be distinguished within the Northern Netherlands with different climate challenges:
- coastal zone with salinization problems;
- peat zone with subsidence problems;
- clay zone with relatively few restrictions.
In the coastal zone, a switch to saline crops is imaginable, both for food production and for other purposes. An example is algae cultivation.
The peat zone between the clay polders and the higher sandy soils is in picture as a climate corridor for water and marsh ecosystems. A more natural water level management is beneficial to reduce subsidence and the intake requirement. Part of the current agricultural land will have to be converted into a nature reserve for this.
The clay polders between the peat zone and the coastal zone will continue to be suitable for large-scale, land-based agriculture in the future. The restoration of natural water supply from the higher sandy soils, via seepage and streams, offers an alternative to inlet from the IJsselmeer.