How will the Dutch lowlands respond when the sea level rises by two and by five metres?
Climate change is not leaving rich countries untouched. Researchers from Utrecht University have mapped what will happen to the Netherlands at two and at five metres of sea level rise if we only maintain the current water management system and do not take additional measures. First of all, the low-lying half of the country becomes boggy and saline groundwater forces its way to the surface. In addition, the rivers rise with sea level along their full length up to the national borders. Not only will all the floodplains along rivers and tidal flats and marshes on the coast be flooded more often, but there will also be a much higher chance of dike breaches and inland flooding. It then takes a long time to pump out the water and reclaim the polders. Furthermore, the Wadden Islands will erode and be washed over. The banks of river estuaries such as the Western Scheldt also erode and dykes will be undercut, again increasing flood risk. At two metres of sea level rise, these effects are less severe and the changes are slower. The rivers in the east of the Netherlands, for example, will then barely rise at all.
This sketch of a future by Utrecht University, commissioned by the Delta Commissioner, shows what the natural response of our delta would be if we take the current situation with human influence as a starting point and take no additional measures. This not only shows us what the Netherlands should prepare for, but also which adaptation measures fit well with the natural behaviour of the delta. If the Earth warms more than 1.5 to 2 degrees, and Antarctica melts, a sea level rise of more than two metres is inevitable. This will require measures such as more room for the upper rivers, natural land level rise along the Western Scheldt and Frisian-Groningen coasts, and living with floods in the west..
The sketch shows how much interest the Netherlands has in progressive climate policies to avoid the above-mentioned drastic consequences. This depends on the success of a global approach to reduce greenhouse gas emissions. For a vulnerable delta like the Netherlands, it is therefore important to anticipate major sea level rise. Radical adjustments in housing, agriculture, industry and infrastructure such as the Delta Works require decades of preparation. By taking this into account now, for instance through spatial planning for retaining, draining and storing water, we can (eventually) take measures that fit in with the natural behaviour of the delta. .
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Sea Level Rise programme
These insights were partly based on research into the development of the Dutch lowlands over the past 3,000 years and recent findings on river and coastal behaviour. The information was brought together and sketched on maps commissioned by the Delta Commissioner's Staff as part of the Sea Level Rise programme.