The Netherlands cannot only cope with a sea level rise of three meters, but even a sea level rise of five meters. Such an enormous increase, which can only be expected in more than 150 years, will require drastic changes in the country, but in that case the Netherlands will still be “safe and livable”. The Randstad will also not lose its function as a heavily populated “economic heart”. However, flooding is increasing and there is insufficient fresh water available to combat salinization at all times and everywhere.
These are the most important conclusions from an extensive series of studies by the so-called Sea Level Rise Knowledge Programme. This program was established five years ago by the cabinet and the Delta Commissioner. The results will be presented at a conference in Bussum on Monday. A few months ago, the Knowledge Program presented the finding that the Netherlands could technically cope with a sea level rise of three meters. It now appears that a higher increase does not necessarily have to threaten the Netherlands – provided that drastic measures are followed.
A first finger exercise
The Netherlands does not yet have to make final choices from a series of measures that can keep the country safe and livable in the event of a sea level rise of more than three meters. The study into the possibilities for adapting the country to climate change from the sea is therefore called “a first exercise”. However, it is worthwhile to take measures now that will work out well in all cases in the distant future, that is “extremely important”.
In any case, the Netherlands will have to live with less fresh water to reduce salt water from the sea, so it is already a good idea to reduce the amount of incoming salt water at locks. Another measure that can already be started now is reserving more space along flood defenses such as dikes.
Randstad must stay
Adapting to a sea level rise of five meters requires a “major effort”, according to the report, such as the construction and maintenance of infrastructure, and the measures also require a lot of space and land use changes. It is “essential” that the Netherlands retains enough earning capacity to finance climate adaptation throughout the country. “This means that areas where the economic earning potential is high must remain protected from flooding for as long as possible.”
For that reason, it is unwise to move the low-lying Randstad, according to research that the Knowledge Program has commissioned. “The earning capacity cannot simply be moved to another part of the country. In addition, there is insufficient space in the Randstad to protect residents and economic value against flooding in any other way. New construction on mounds does not provide enough space for the large number of residents and ring dikes around urban areas are ultimately more expensive than maintaining the current flood defenses.” “History also shows,” according to the report, that moving an economic core of a country “is difficult to manage.”
Three types of adjustments
There are roughly three different ways in which the Netherlands can adapt to sea level rise in the longer term, the report shows. The first is to ‘move along’ with the consequences of sea level rise, utilizing the ‘forces of nature’. “Consider, for example, elevated or floating housing, salt-tolerant agriculture and a shift of investments to the high Netherlands.”
The second is to strengthen the current strategy to protect the country against the sea with dike reinforcements, storm surge barriers, locks, weirs, pumping stations and pumps. River estuaries can even be closed off.
The third way is the seaward approach: the construction of a large lake off the coast of the south-west of the Netherlands. “We use this lake to temporarily store high river discharges and reduce salinization.”
River water safely to the sea
Making a choice from one of these “schools of thought” is not an issue now. In practice, a combination of measures from the three methods of adjustment will probably work best. In all cases, it is important to consider how the Netherlands can safely and quickly transport the large volumes of river water from the Rhine and Meuse to the high seas.
In the longer term, the Knowledge Program states, national choices are necessary on the following issues: the distribution of the Rhine river water; the possible closure of the Rijnmond, possibly with specific protection for Rotterdam and the Drechtsteden, perhaps by turning it into a ‘Deltapolder’; the storage of river water in the southwestern delta waters; the construction of a lake off the coast of the southwestern delta; raising the water level in the IJsselmeer; whether or not to stimulate habitation and economic activity in more vulnerable parts of the Netherlands.
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Antarctic meltdown
The Knowledge Program studies were initiated following reports of a possible acceleration of the previously expected sea level rise. This acceleration, the researchers write, will become even stronger if Antarctica melts faster. “Then the sea level could be two meters higher around 2100 and a rise of up to five meters by 2200 cannot be ruled out.”