Tiengemeten is an island estuary of the rivers Rhine and Meuse, just south of Rotterdam. Since the last embankment in 1860, Tiengemeten consists of 700 ha arable land and 300 ha reedbeds. As a result of the construction of a dam in 1970, the tidal ebb and flow in the estuary practically ceased. The effect has had serious consequences for the vegetation and fauna of the Haringvliet, including the island of Tiengemeten. The intertidal surface area with its characteristic mud flats and salt marshes had shrunk as the ecological gradients disappeared.
In 1990 the Dutch government decided to incorporate Tiengemeten in the Ecological Main Structure (EHS), the network of existing and new nature reserves in the Netherlands. In more than one way a radical decision: for the benefit of the rare freshwater tidal habitats, but also radical for the six farming families that had to leave the island to make room for nature.
Previously, there had been plans for all sorts of uses for the island, including a dredge depot, a nuclear energy facility, and an amusement park. The island was also mentioned in plans made by the municipality of Rotterdam for large-scale developments in the area to expand its harbour; in these plans, an airport was to be built on the island. But of all these choices, the island was ultimately designated a natural area.
The restoration project would focus on the 700ha agricultural area of the island. The LIFE-Nature part of the project would aim to create a 660ha large freshwater tidal landscape.
Three spheres would be created, where nature, recreation and the cultural remains of the history all have their place. Nature dominates the largest part called ?the Wilderness? (Wildernis). The central and easily accessible part demonstrates the richness of the ecology called ?the Wealth? (Weelde). These two spheres were part of the LIFE-project. Parallel to the LIFE project, the eastern part of the island would have been restored to its original state, traditional farmland. This part of the island (about 40 ha) is called ?the landscape of Nostalgia? (Weemoed).
The largest part of Tiengemeten, the Wilderness, is now directly connected with the Haringvliet estuary by a large tidal creek. The surrounding dyke is lowered and at one point pierced to connect the polder with the Haringvliet. High and low tide will give rise to expansive areas of reed beds scrub and smaller creeks.
By nature the middle part of the island is a little lower than the rest and the soil is pretty impervious. Here is the Wealth-part. The surface level of the Midden- and Benedenpolder would have been lowered even more here and there. Shallow marshes can now develop: dry in the late summer, but one large, open stretch of water in the winter. Thousands of geese, widgeons and other ducks have already come here to rest undisturbed. In the spring, mud banks would gradually come clear of the water. A favourite foraging habitat for spoonbills, egrets and thousands of waders.
Targeted species are the root vole (Microtus oeconomus). Additional target species of the project were the sturgeon (Acipenser sturio ? to be re-introduced at a later stage), the corncrake (Crex crex) and the bittern (Botaurus stellaris).
Tiengemeten was intended to become an island for nature-based recreation, popular in Rotterdam and the southern Netherlands. LIFE-Nature has also contributed to the visitor?s centre that is now operating in this large Natura 2000 site.
The project was highly successful and achieved all its goals. Its main successes were the construction of the new visitor's centre, the completion of the opening of the dams (and securitisation of the human settlements) and efficient flooding of the island, and the social acceptance of the transformation of the 700ha of farmland into tidal ecosystems.
The project is expected to lead to the increase of rare and endangered species in the site, which will also affect their status at a European level. There is a real possibility to observe in the future an increase in the populations of bittern at European level as many other projects have been implemented for this bird directly or indirectly in other countries (Belgium, France, UK etc.).
The project forms part of the wider Deltanatuur initiative to restore and create thousands of hectares of valuable habitats in the estuary and create an ?ecological main structure? in order to enhance or restore connectivity between large areas of nature. The Deltanatuur project aimed also to restore a more natural and important natural tidal regime. The specific target on Tiengemeten was the restoration of freshwater tidal habitats, an important goal owing to their rarity in Europe.
After the disastrous floods of 1953, the Delta Works were constructed in The Netherlands. Dykes were strengthened and storm barriers were built to keep the sea out. The land is now well protected, but the tidal nature that was common in the south-west part of the Netherlands has almost disappeared, also along the Haringvliet estuary. Before the Haringvliet was closed off from the open sea, there was a two-metre difference between high and low tide and the environment was saline. Since the closure the tidal range has shrunk to 30 centimetres and there is now a freshwater environment. Numbers of estuarine and marine species have declined dramatically. Migratory fish, such as shad, have all but disappeared. The Haringvliet floodgates will be opened up gradually the coming years, allowing the tidal range to increase and allowing more exchange of salt and fresh water. This is a long-term project. The final scenario is not yet fixed but eventually the tidal range will go up to 60 cm and the ratio of salt to fresh water will increase. Fish are expected to benefit from this.
Tiengemeten will remain a fresh water tidal area, though. The salt sea water itself will not reach the islands? tidal creek, but the tidal range will increase, improving the conditions for Wilderness to develop.
The management of such an extended area (1000ha) will continue to face costing issues. The chosen options of spontaneous evolution (influence of the tides) and extensive grazing have a good potential.
The active involvement of public authorities and the owner, Natuurmonumenten, a very big NGO, are positive factors for the future. A future management plan, ?Maatregelenplan Tiengemeten 2007-2024?, was drawn up as a ?After Life conservation plan?.Further information on the project can be found in the project's layman report (see "Read more" section). This project has been selected as one of the 26 "Best" LIFE Nature projects in 2007-2008.