Netherlands: artificial islands revive ecosystems
Markermeer, one of the largest freshwater lakes in Europe and the Netherlands, was once famous for its abundance of fish and other aquatic life. However, for natural reasons, this vast area of 700 square kilometres, which is also a regulator of water levels in the rest of the Netherlands, has become a cloudy mass devoid of aquatic life.
The pond is part of the IJsselmeer or former Zuiderzee shallow bay in the North sea in the North-Western part of the Netherlands. In the 20th century the majority of the Zuiderzee was closed off from the North Sea by the construction of the Afsluitdijk, leaving the mouth of the inlet to become part of the Wadden Sea.
This scheme of reclamation of land and water from the sea was realized at a high price for the environment. Over the decades, sediment used to create a dyke separating the Markermeer from the Ijsselmeer, washed away and sunk to the bottom of the lake. Because of this, the water became turbid, which negatively affected the populations of fish and birds, plants and mollusks.
A new artificial archipelago of five islands inspired life in a fragile ecosystem.
This ambitious engineering project for a country below sea level, which has had to manage the risk of flooding for centuries, was initiated by the Dutch environmental NGO Natuurmonumenten. The project cost 60 million euros, most of which was donated by individuals.
Five islands called Marker Wadden were built in two and a half years and this year turned into a resting place for 30,000 swallows. Recently, experts counted 127 plant species, most of which migrated to the islands by wind. There is a surge of plankton growth in the water, this guarantees a large amount of food for the birds.
Gray goose, common tern, great egret and night heron returned to the region, which indicates the ecological success of the island project.
True to their reputation as masters of hydraulic engineering, the Dutch used an innovative method in the Marker project - the soil of the islets was formed with silt. This sedimentary rock consists mainly of mineral grains (quartz, feldspar, mica and others) and occupies an intermediate position between clay and sand.
Building an island with sand is not that difficult, we do it all over the world, and what is unique here is that we use silt, says Jeroen van der Klooster, project head at Boskalis company, that built the islands.
The project team has dug a 1,200-metre corridor on the main island, which allows silt, driven by strong sea currents, to feed the soil and form marshy lakes for recreation of migratory birds.
The main island accommodates three wooden bird observatories, sentry points, 12 kilometres of pedestrian bridges and underground walkways for visitors. The remaining four islets are reserved exclusively for wild flora and fauna.
It should be noted that Turkmenistan also has experience in the construction of stationary hydraulic marine structures. In the waters of the Turkmenbashy Gulf of the Caspian sea during the construction of the port complex, a unique island in the form of a crescent was created, which today is of ornithological importance, and in the future has a chance to become a site of ecological tourism.
