The Roggenplaat is an important feeding area for birds as well as a resting place for seals in the Eastern Scheldt. Over the past 25 years, the Roggenplaat has decreased in size due to sand erosion that is caused by sand nourishment. This is caused because the deep channels in the Eastern Scheldt are the same size as before the construction of the Eastern Scheldt storm surge barrier, while the water volume that flows in and out has decreased by 25%. This has caused a disturbance in the dynamic that is necessary for the formation of plates, mudflats and salt marches. The sand moves from the higher plateaus to the lower plateaus of the Roggenplaat which means that the plate falls dry for a shorter period of time. The time that a plate falls dry must be long enough for the birds to forage (eat).
Feeding area for birds and resting place for seals disappears
If no measures are taken, the natural function of the Roggenplaat will be in danger. It is expected that in 2060 no area will dry up long enough for birds to forage in the winter. In 2100 this will be the case for summer as well. This seems far off in the future, but the situation will already become critical around 2025. It is important to take measures now so the higher areas will not disappear.
Lost sand back to the Roggenplaat
The objective of the research project Roggenplaat is to bring back the ‘lost’ sand by means of a large sand suppletion. This happens by creating approximately 200 hectares of extra area with the help of 1.3 million cubic metres of sand in the key zone. The key zone of this project is the area that falls dry for more than six hours. Waders need this amount of time to properly forage. Due to the suppletion, the forage area on the Roggenplaat will almost double. It is expected that it will be back to the current level sometime after 2040.
Water safety is an objective as well
The main purpose is to maintain the forage and rest area for the next 25 years, which benefits the water safety as well. Elevating the Roggenplaat will namely decrease the wave impact on the south coast of Schouwen. Finally, the objective is to gather expertise for the flexible, climate-proof and cost-effective management of the coastal zone. The sand suppletion will take place in 2017-2018. The initial situation is monitored and determined in 2015 and 2016. At the same time, the design for the construction of the suppletion will be developed in consultation with stakeholders such as The Society for the Preservation of Nature [Natuurmonumenten], and the shellfish industry.
Partners that are involved in this project are Ecoshape, Deltares, IMARES Wageningen UR, NIOZ and The Department of Waterways and Public Works. Joost Stronkhorst is the contact person for this project.