A test site for salt marsh development was opened on 2 November at Delfzijl. The salt marsh landscape is part of the ‘Marconi Buitendijks’ scheme and will be a testing ground for the next three years. Researchers will investigate different strategies to develop salt marshes. The project is part of the Eems-Dollard 2050 Program and is the result of a collaboration between the municipality of Delfzijl and the EcoShape knowledge consortium. The Wadden Fund is a co-financier.
The 15-hectare salt marsh landscape has been divided into a number of test sections that differ in soil composition and planting of samphire. Project leader Petra Dankers of EcoShape explains: ‘The subsoil of the salt marsh landscape consists of sand and clay, just like the natural subsoil of a salt marsh. To find out which ratio of sand and clay works best for salt marsh development, we have added 5%, 20% or 50% clay to the top layer of sand in the test sections. ‘
This winter the researchers measure height changes, development of channels and erosion and siltation of the salt marsh, to map the initial situation. Petra continues: ‘In the spring of 2019, the researchers plant samphire in a number of test sections to see if and how planting works and how the vegetation of the salt marsh develops.’
The municipality of Delfzijl faces a number of challenges. The sea level is rising and the ecosystem is being threatened because of excessive levels of sediment in the Ems Dollard estuary. Next to that, the municipality wants to increase the attractiveness of the city. EcoShape therefore made a Building with Nature design for the coastal area near Delfzijl, containing a beach, a salt marsh park and a salt marsh landscape. The municipality commissioned EcoShape to conduct the research into salt marsh development on the landscaped salt marsh landscape. Mr. Jan Menninga of the Delfzijl municipality explains: ‘With the delivery of the salt marsh landscape an important step has been taken. We see how the city is being better connected to the Wadden Sea. We look forward to the results of the EcoShape research. ‘
The knowledge that the researchers develop can be applied at other places in The Netherlands and abroad. Petra Dankers: ‘The problems in the coastal area of Delfzijl are not unique. Worldwide, many coastal areas are affected by the rise in sea level and land subsidence. In Delfzijl we now build valuable knowledge and experience with the construction of salt marshes that can serve as natural coastal protection. In time, the expertise will also help other port and delta areas to develop salt marshes with natural and location-specific materials. ‘
EcoShape is a consortium of hydraulic companies, engineering firms, knowledge institutions, NGOs and governments that develops knowledge about Building with Nature in hydraulic engineering: a new way of design that uses nature to create opportunities for nature, economy and society. In this project at Marconi, EcoShape partners are working together with Royal HaskoningDHV, Wageningen Marine Research, Arcadis and Deltares.