Netherlands currently safe against rising sea levels; Salinization a more urgent problem

The Netherlands’ current approach to water defense will likely be enough to keep the country safe against the rising sea levels in the coming decades. “It is technically possible to protect the Netherlands against a sea level rise of up to 3 meters,” according to an interim report by the Sea Level Rise Knowledge Program.

A much more urgent problem caused by the advancing seawater, combined with the other factors of climate change like warmer and drier weather, is that fresh water is becoming scarcer. The Netherlands must prepare for that, the Sea Level Rise Knowledge Program - in which knowledge institutes examine how to protect the Netherlands against rising sea levels - said in the report sent to parliament on Thursday.

Saltwater is contaminating the freshwater via the groundwater, the rivers via the Nieuwe Waterweg, and through sea locks like in IJmuiden and the Afsluitdijk. In the past, there was enough river water and rainwater to wash away the salt. But the hotter and dryer weather is already changing that. “Prolonged periods of drought and low river discharges are already putting pressure on freshwater availability.

The government is examining ways to protect the Netherlands’ fresh water as well as possible. They’re looking at preventing the inflow of saltwater at locks, as well as possibilities to better retain fresh water and how to use the available resources more economically.

According to the most recent climate predictions, the Netherlands will see sea levels rise more than 3 meters a little after 2100 in the worst-case scenario and only after 2300 in the best case. The Netherlands’ current strategies - supplying sand to keep the coastline in place and strengthening dunes, building dikes, dams, storm surge barriers, and locks - are therefore sufficient to keep residents’ feet dry for the coming decades.

But that can’t go on forever, the experts said. Spatial challenges are already making things complicated. For example, higher dikes also need to be wider, as much as 90 meters wider, to accommodate 3 meters of sea level rise. That does not fit in with existing buildings everywhere. Moreover, up to four times more sand will have to be supplied per year, and the extractable sand in the North Sea is a limiting factor.

The Ministry of Infrastructure and Water Management reported earlier this week that some 2,100 kilometers of the Netherlands’ flood defenses need reinforcement and repairs. According to the report, that is to accommodate a sea level rise of one meter.