Putting a healthy beat into Holland’s ‘wet heart’
AMSTERDAM _ Over the centuries, the Dutch have struggled hard in the service of dry feet. It has long been a life of toil and it continues today. Climate change is forcing this flat, low-lying nation to upgrade seawalls, dams, dikes, dunes and locks. But it is also _ boaters sit down for this good news! _ rethinking the arch-Dutch habit of clawing back land from the sea.
In the Netherlands, land reclamation is less of an imperative than it once was. Nowhere is this more evident than in the North Sea inlet that was cut off by a 32-km causeway in the 1930s creating the IJsselmeer, a freshwater lake of 1,100 sq. kms. In the years ahead, the Afsluitdijk causeway will be upgraded to better protect the lake. Ringed by old, gabled ports and newer towns on land wrested from a once unforgiving sea, the IJsselmeer is today a peerless boating area and a hub of Dutch yacht-making.
But not all is well is Holland’s “wet heart.” In the 1970s, a second causeway was built through the IJsselmeer. Its lower part _ 700 sq. kms off Amsterdam, called the Markermeer (dark blue on map) _ was to be pumped dry and turned into land for cities and agriculture. But a lack of national consensus on that option triggered 25 or so years of dawdling during which the quality of the water deteriorated sharply. “The ecological system of the area is downright bad,” ecologist IJsbrand Zwart of Flevoland province told the Amsterdam daily De Volkskrant in July, 2012. “The food pyramid is teetering. The base is formed only by zebra mussels, smelt and some aquatic plants.”
Boaters crossing the Markermeer can see the legacy of fence-sitting. Even modest winds can stir up sludge and silt from the bottom of the shallow Markermeer (5.5 m., on average) turning its water a hazy, guacamole-green. There is no significant fish life in sight. The government has ambitious plans to undo years of neglect and restore the lake’s habitat. Half a dozen test projects will show by 2015 how that’s best done. These projects include:
__ deploying an artificial reef, 73 x 20 meters and made of biologiocal material, to see if and how it can stimulates plant and fish life, create food for aquatic birds and clear up the water.
__ lowering 75 concrete domes _ 800 kilos a piece _ over an area of 30 x 40 meters on the lake bed. Punctured with holes, they resemble huge hard hats that must create underwater areas of shelter allowing aquatic plants to grow and mussels and fish to spawn and rest.
__ building four test basins to see how marshes and swamps can thrive
__ crafting wave-free, clear water zones off the town of Hoorn (whose native son Willem Schouten named Cape Horn when he rounded it in 1616) and a temporary 1,800-m seawall to see if these can keep silt down on the bottom.
Zwart and others favor very wet swamp lands that rule out tall trees but encourage sea birds to nest. Others dream of an archipelago of artificial islands and swamps. “How exactly we will create a more stable Markermeer ecology remains unclear at this stage,’’ says Mirjam Stoffer, a spokeswoman for the Dutch water management department told Y&C. “We will make a recommendation to the government at the end of 2015. It is a political choice that needs to be made.”