Due to the construction of the storm surge barrier there is a ‘hunger for sand’ (sand nourishment) in the Eastern Scheldt. The tidal range is reduced which has caused a distortion of the balance between erosion and sedimentation. When the weather is calm, the intertidal zone does not sufficiently rebuild itself, while it does deteriorate during a storm. Due to this, the surface of plates, mudflats and salt marches in the Eastern Scheldt decreases which has a negative impact on the natural quality and which increases the wave load on the dykes.
The Department of Waterways and Public Works researches possibilities to manage these negative effects. One of the possibilities is to elevate certain vulnerable areas with sand. Various pilot studies are currently underway in the Eastern Scheldt, including the sand suppletion at the Oesterdam. In November 2013 approximately 350,000 cubic metres of sand has been added over an area of two square kilometres. The work of sand must ensure that the lifespan of the dyke will be increased and that the dyke doesn’t need to be reinforced for another 25 to 30 years. At the same time, these sand suppletions slow down the disappearance of the local intertidal zone and help to restore nature and the landscape. In order to demonstrate that the local elevation of the intertidal zone is effective, much research needs to be done. Where is the sand moving to? Are the artificially created oyster reefs on the suppletion helpful in retaining the sand? How long does it take for soil life to return and which factors determine the colonisation? Many questions that are essential to determine if this particular suppletion method is successful and applicable on a large scale.
Monitoring and Research, Safety buffer
The Department of Waterways and Public Works has requested the partners of the Centre of Expertise Delta Technology to conduct this research. In addition to the questions that are listed above, the Centre of Expertise Delta Technology also involves students who are taught about this new form of coastal management through work placements, guest lectures, excursions and specially developed modules. This way, the partners of the Centre of Expertise Delta Technology contribute to a quality impulse of education and the training of future delta professionals.
The project started in January 2014 and will run until December 2017. Partners that are involved in this project are The Department of Waterways and Public Works Sea and Delta [Zee en Delta], IMARES Wageningen UR, Deltares and NIOZ.
More information about the Oesterdam project can be found on the website of The Department of Waterways and Public Works. Matthijs Boersema is the contact person for this project.