The Delta Programme of the Netherlands Government is describing and proposing a national climate adaptation policy concerning flood protection and freshwater supply. This includes a gradual rise of the IJsselmeer lake level, along with the rising sea level. The proposed new water level management in Lake IJsselmeer has negative consequences for the valuable areas outside the dikes along the Frisian IJsselmeer coast, and for water safety for the area behind the dikes. The areas outside the dikes are vulnerable and at risk for inundation when the new water level management will take place, as proposed in the Delta Programme.
The IJsselmeer is a former sea arm in the Netherlands, separated from the sea in 1932 by a 32 km long dam, the Afsluitdijk. Along the northeast coast of this lake, the former saltmarsh has developed into valuable freshwater wetlands which help protecting the shore of the province of Friesland. In 2009, planning started of three so-called ‘sand engine experiments’ along this shore, meant to investigate whether a gradual supply of sand would enable the wetlands to follow a rise in lake level along with sea level rise. The implementation is governed by a coalition of regional and national actors, led by It Fryske Gea, a regional NGO for nature protection.
The flexible water-level management that is needed to increase the buffer of freshwater requires additional protection of these areas outside the dikes. An increase in water level of ten centimetres results in more than 100 hectares of land that will be flooded. Without additional measures, the areas outside the dikes will be eroded. These areas are important for nature conservation, recreation and water safety and therefore the stakeholders along the Frisian IJsselmeer coast develop a strategy for sustainable coastal protection. The challenge is to make the Frisian IJsselmeer coast resilient enough to be able to withstand the negative effects of a higher water level. Also when the water level in the future increases even further.
The project ‘Zachte Zandmotor’ along the Frisian IJsselmeer coast aims to develop knowledge about how a sand engine can lead to a more sustainable, less expensive and environmentally robust way of coastal defences. The function of a sand engine is based on the use of natural processes in the defence of the coast related to future water level rise and water level fluctuations. With this knowledge, the Ecoshape partners want to provide a sound basis on the operation and effectiveness of a sand engine in a lake environment, in order to make a wider application of the concept possible. The knowledge gained in this project will be used to develop a strategy for sustainable protection and enhancing the spatial quality of the entire Frisian IJsselmeer coast.