Oosterschelde

Oosterschelde National Park was established in 2002 in the province of Zeeland and at some 370 km² it is the largest national park in the Netherlands. It protects the estuary of the Eastern Scheldt, an arm of the sea reaching in between the delta islands.

Its existence is the result of a singular political decision. After the catastrophic flood of 1953, the Delta Plan called for closing the Oosterschelde completely with a dam, which would have turned the estuary into a freshwater lake and destroyed its tidal ecosystem and the shellfish industry. Opposition from fishermen and conservationists led to a change of project: instead of a closed dam, the Oosterscheldekering was built, a nine-kilometre barrier of movable gates that stays open in normal conditions and closes only against storm tides. Opened in 1986, it is the greatest work of the Delta Plan and made it possible to keep the tide, though with a reduced range.

The estuary thus keeps tidal flats, sandbanks and seagrass meadows that support a rich fauna: harbour and grey seals hauled out on the banks, porpoises, waders in their tens of thousands and a benthic life that sustains mussel and oyster farming. A side effect of the barrier, the so-called sand hunger, is progressively eroding the tidal flats and is today the main conservation problem.