[Video] The return of the herring

The Haringvliet is the setting for a unique ecological experiment. The sea lock will remain partially open to allow salty sea water to mix with the fresh water of the lake.

Nature finally gets to recover from the impact of the Delta Works of half a century ago. (Photo: Wikimedia Commons)

The Haringvliet lies south of Rotterdam, where the Rhine and Meuse rivers flow into the North Sea. It is an enormous body of water which historically had a big tidal range. “It consisted of a lot of sandbanks and had a lot of herring, hence the name Haringvliet,” explains Bas Roels of the World Wildlife Fund. The word haring in Dutch means herring.

“We want to bring this historic natural landscape back,” says Roels. “The World Wildlife Fund thinks that the Netherlands should open the delta, which was largely closed by the Delta Works decades ago, more for nature and for the migratory fish, the different bird species and the seals that live there. That’s why an island, a sandbank called ‘Bliek’, was recently created at the centre of the Haringvliet.”

Changing ecosystem

The TU Delft Faculty of Architecture is involved in changing this landscape and studies the changes in housing and the living environment. “When salt water enters the system there are consequences for agriculture and the fresh water supply,” explains Dr Steffen Nijhuis. “The ecosystem changes, fish start to migrate and the area becomes more dynamic because of the influence of tides.”

But besides these consequences, the changing ecosystem opens up the possibility of taking a different look at the spatial development in the area. “This project has much potential to develop into a resilient, estuarine landscape with flexible transition zones between land and water. It could have multifunctional flood control, amphibious living, living on mounds, alternative forms of agriculture and could also have extraordinary ecosystems and be a centre of recreation.”


The Haringvliet may well become a livelier place, but farmers in the region fear the encroaching sea water. They are worried about soil salinisation. “We do look at possible risks,” reassures Daan Markwat. The alderman of Goerree-Overflakkee acknowledges that the farmers on his island need fresh water to cultivate their crops. “We have talked with the different sides about compensation measures. A new freshwater canal has been constructed that guarantees a sufficient supply of fresh water for crops in the future.”  


As of now, Rijkswaterstaat, the executive arm of the Dutch Ministry of Infrastructure and the Environment, has set up a monitoring network to control the intrusion of seawater into the lake. This minimises the risks, while giving nature the opportunity to recover from the Delta Works of half a century ago.

TU Delft TV shot a short documentary on this ecological experiment. Make sure to watch it below.