Nature islands Marker Wadden:
Co-creation between man and nature
When humans create the conditions, nature responds impressively fast. The Marker Wadden, an archipelago in the Markermeer, is powerful evidence. Initiated by Natuurmonumenten and Rijkswaterstaat, the nature islands were created from sand, clay and silt. Witteveen+Bos was involved in the design, construction and nature development of the first islands. We also played an important role in the accompanying research into further developments on the islands by employing remote sensing and deep learning technology.
The decline of the ecosystem in the Markermeer is the reason for the construction of the Marker Wadden. The Markermeer is a relatively shallow, wind-sensitive lake. The bottom is covered by a thick silt bed that is strongly stirred up thereby disrupting the life of plants, insect larvae, crustaceans and shellfish. Combined with decreased water nutrient richness, biodiversity is declining.
Nature restoration
The Marker Wadden project was launched in 2016 to restore nature in the lake. The contract to create an initial series of islands was awarded by Rijkswaterstaat to the consortium comprising Boskalis, Arcadis, Vista landscape architects and Witteveen+Bos. We played several roles in the project. During the design phase, our ecologists worked on the design of the islands and created a plan for the intended wildlife development.
Building with silt
During and after the realisation phase, our ecologists were responsible for developing marsh vegetation on the islands on behalf of Boskalis. Finally, our ecologists and remote sensing experts collaborated on the accompanying scientific research programme KIMA, which examined all developments on and around the islands for five years.
Within the Marker Wadden Knowledge and Innovation Programme (KIMA), Witteveen+Bos together with Deltares developed the topic ‘Building with silt’. This topic included investigating subsurface settlement and silt consolidation, including the influence of vegetation on them. A synthesis report of the design and results of all studies was recently published.
Accurate vegetation monitoring
To track vegetation development on the Marker Wadden, Witteveen+Bos harnessed the power of remote sensing using drone images. Whereas publicly available satellite images offer a maximum ground resolution of 0.5 metres, images taken by the drone with 5 cm ground resolution are significantly more accurate. The relatively small-scale vegetation on the Marker Wadden, especially in the early years, required a more accurate analysis.
Customised model
Tailored to the available images, our team has developed a customised model to recognise vegetation. Deep learning was used in developing the software. From a database of hundreds of images, the software learns to recognise the vegetation on the drone images.
The model sees cut-outs from the drone images of the Marker Wadden in which it is annotated exactly which species are displayed. The model uses the images to associate structures in the image with vegetation. By then ‘showing’ the model the entire Marker Wadden, a map is created of the most likely vegetation in the area on the day the images were recorded.
Wide-ranging technology
The development of the vegetation was monitored based on maps for the years 2018, 2020 and 2021, focusing on the most common vegetation species, including willow. High-resolution images, or the corresponding analysis technology, is useful for many forms of local aerial monitoring. This includes road surfaces, banks or dunes. Basically everywhere where details are important, for example for maintenance purposes.
Marker Wadden is a major project being realized by Natuurmonumenten, Rijkswaterstaat and Boskalis. The goal is nature restoration of the Markermeer. By constructing nature islands with sand, clay and silt from the Markermeer, new nature will develop, both under and above water. A rich habitat for fish and birds and a recreational island.
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