Fingering a New Dike
Whatever happened to the Zuiderzee?
Literally the “South Sea,” this was a characteristic geographic feature of Holland that many of you may have caught mention of when reading about Rembrandt, say, or about the Dutch East India Company (or, for that matter, the Dutch West India Company), whose ships generally set sail from Amsterdam through the Zuiderzee on their way to found/supply/exploit the various Dutch colonies in the world.
But you don’t hear about the Zuiderzee nowadays, and that’s for a good reason: it was eliminated back in 1933. No, that big body of water lying in the middle of the Netherlands did not just dry up, but in that year it was rather cut off from the North Sea and turned into basically a big lake by a modern and uniquely Dutch engineering marvel, the Afsluitdijk, or “Closure Dike,” spanning 32 km/20 miles from the provinces of North Holland in the West to Friesland in the East. The Zuiderzee was at that point renamed the IJsselmeer (after the IJssel, the main river to run into it) and slowly but surely turned into a fresh-water lake.
Construction of the Afsluitdijk lasted from 1920 to 1933, and its total cost, 200 million guilders, was equal to the entire Dutch yearly state budget of those times. This we are told by Peter Maurits in a recent article in the Dutch newspaper Trouw (The New Afsluitdijk: Sober or Bling-Bling). He also notes that the immediate reason why the Dutch government at that time saw such a measure as necessary was the continual misbehavior of the Zuiderzee, whose constant pattern of storms posed a serious threat to the often low-lying lands on either side of it, culminating in the “South Sea Flood” of 1916 which did considerable damage to North Holland. Cutting it off from the sea did calm it down – as well as setting the pre-conditions for carrying out further drainage on the resulting IJsselmeer that brought about the creation of an entire new Dutch province, Flevoland, officially inaugurated on 1 January 1986.
Global Warming Means New Dike
But this information not what Maurits’ piece is about; it’s rather by way of background. What his piece is about, is that after 75 years in use the Afsluitdijk as it now exists has become inadequate to its assigment, and so must be replaced. Specifically, the government-required standard is that the dike be strong enough that the chance that it can break can be no more than once in 10,000 years, but at present that chance is evaluated as closer to once in 1,430 years. Yes, pace the Washington Post’s Joel Achenbach, most of this has to do with global warming: the sea level is forecast to rise by as much as one meter over the next hundred years, so that a stronger dike is needed than is present now.
The tender is out for an Afsluitdijk replacement, then, and the first proposals have been made by a total of eight engineering consortia (all Dutch-based). What Maurits’ article is really about is surveying these proposals and comparing them to the desiderata of the new dike, both as to what is absolutely required and what would be nice to add as features/capabilities to the dike, since we have to fix it up anyway – as long as it doesn’t cost too much. Among these secondary desiderata is perhaps some way to generate energy out of the new installation, as well as a kindlier treatment of the marine life on either side. (The salt water-based fish and other wildlife who were caught on the IJsselmeer side when the dike was completed in 1933, so that the new lake on its south side could gradually become fresh-water, found themselves simply out of luck. Similarly, there is a continuing necessity to emit some of that fresh water from the IJsselmeer through the dike and into the North Sea, since after all it is being replenished all the time to the rear with water ultimately flowing down from the Alps, and so otherwise would quickly overflow. But the salt-water marine life living on the dike’s northern side really doesn’t like dealing with too much of that fresh water at one time.)
A Dike-Solution Taxonomy
Let’s follow along with Maurits’ classification-system of these eight proposals, which he breaks down into “Long live Nature” (i.e. nature-friendly), “Minimalist,” and “Maximalist.” (By the way, the original article does feature handy “artist’s-conception” illustrations of the new dike proposals at the head of each of these three sections.)
Nature-friendly
One of the consortia, the Wadden Werken project, has a particularly interesting proposal: it proposes to, in effect, considerably extend the dry-land part of the dike out into the North Sea. All that would be necessary to start would be dumping sand on the seaward side of the dike so that the sea floor comes up to about just 40 cm underwater; the natural action of the tides would then do the rest, first of all to wash up additional sand against the dike so as to raise the floor so that it is eventually just above water, and thereupon to foster the growth of vegetation, whose roots would in time help to hold everything together even in the face of violent storms. The end-result would be the sort of dry-ish marshy landscape that you often see in the Netherlands, for example, alongside rivers between the river and the actual dike that is there to make sure that, in the case of high water, it goes no farther – an area friendly for wildlife and whose name in Dutch is kwelder (a word I learned from this article for the very first time). Finally, at some place within this new kwelder a channel would be cut for the necessary draining of fresh water out into the sea – but the channel itself would function as a sort of mixing-bowl to ensure that that water is already pretty salty by the time it does hit the open sea.
Then there is the proposal from the “Afsluitdijk of the 21st Century” group. They directly address the salt-/fresh-water problem mentioned above by proposing (in addition to the required strengthening of the Afsluitdijk itself, of course) creating a sort of salt/fresh no-man’s-land by erecting a second, less-substantial dike to the rear of the main one. The area in between would be that no-man’s land, with outlets for water in both directions to enable subtle control to ensure that neither the fresh-water fish on the lake side nor the salt-water fish on the sea side ever have to deal with any excess of the sort of water they don’t like.
Minimalist
Among Europeans, the Dutch are rivalled only by the Scots in their reluctance to spend money, so you would have to think that any group coming forth with a plan simply to strengthen the Afsluitdijk as it needs to be strenghtened – and that’s it – would be attractive to the selection-panel of government and regional officials that will ultimately have to choose a solution. Spokesman Marco Tanis of the “Monument Afsluitdijk” consortium declares “We want no ‘bling-bling’ on the dike,” and indeed this group’s proposals are fairly simple. First make the dike higher, since waves washing over it during storms are damaging to its stability. Then you “green” those new, higher sand dunes with vegatation, again to call forth the “plant root” effect to strengthen the structure. Ultimately (i.e. later on), if the predicted sea-level rise comes true, then the dike will also be widened, on the lake side, to make it even stronger. Interestingly – and perhaps inconsistently – “Monument Afsluitdijk” are willing to make a gesture to the fish, namely by building a sandbank at some point along the new dike, across the dike so that it has an end in the sea and in the IJsselmeer, whose purpose would be to provide a solid and welcoming structure that the fish could lay their eggs in.
The consortium “Monument in Balance” is also classed by Maurits as “minimalist,” and their spokeswoman, Annewil Lucas, declares “We don’t want to make a Christmas tree out of it.” But they also see no need to build up the dunes to make it higher, either; they will make it higher with a wall. Further, just like “Monument Afsluitdijk,” they propose a policy of wait-and-see for the rising sea level; if it happens, then the dike can be widened as necessary later.
Maximalist
Then again, for such a major public works project you will always be guaranteed to get proposals designed to use the opportunity to accomplish some neat things on the side. You have, for instance, Mr. Wubbo Ockels of the TU Delft (the Netherlands’ leading technical university; Ockels went up on the Space Shuttle in 1985 as the first Dutch astronaut, by the way), who declarees that “The project can go ahead and cost money, because in the end you’ll earn that back.” So Ockels proposes putting a structure on top of the entire new dike that will not only block waves from washing over, but which can also carry a vast array of solar cells to generate electricity. He also is an enthusiast of the idea mentioned above to construct a second dike behind the first (i.e. in the lake), but for him it would not be for the wildlife’s sake; it would be to generate additional energy via a certain osmosis process that occurs when fresh water is mingled with salt water. There’s a another consortium, called “Pump or Drown,” which proposes using zandworsten (“sand-sausages”) to in effect create yet another dike further out to sea. These are huge bags made of durable plastic, sausage-shaped, which could be stacked to make that new outer dike and so let the area between those barriers and the Afsluitdijk dry up (to a greater extent than in the kwelder proposal described above) and so be accessible to nature-lovers and pick-nickers. The good thing about “sand sausages” is that, if you decide you don’t want them anymore, you just pierce the plastic and the sea will do the rest to level down the sand and destroy that temporary dike.
Oh, and finally, the consortium Grietje Basker (that must be someone’s name) proposes building houses and/or apartments along the new dike – apparently on the assumption that people would actually want to live there. Maybe on weekends and holidays, using them as holiday homes?
As already mentioned, the decision about what to actually do to get a new Afsluitdijk will be made later this year by a commission composed of the national cabinet minister for Traffic and Waterworks and representatives of the provinces and counties (gemeenten located at either end. As you might expect – and although to some degree some of the plans are mutually exclusive – it is assumed that the decision-making process will involve picking-and-choosing from the individual features and proposals making up the different plans, in the style of a Chinese menu.
