Nature enriched structures
Low-lying delta areas often use dikes and other hard coastal defence structures to protect the land against flooding, and harbour structures such as piers, docks and jetties for transport purposes. On top of their primary function, these structures are often used by a variety of plants and animals for growing, reproduction, nursery and feeding.
Coastal defences can be improved in this respect by adapting traditional coastal engineering structures to this ecosystem function. This may even have a positive effect on the structure itself: extra dike stability and wave damping may be provided by deliberate introduction of vegetation such as saltmarsh, reeds, shrubs or trees. Eco-friendly revetments can contribute to the ecological value of a dike and – depending on their location and design, dikes may also host a range of other functions such as living, meadow-land and recreation.
Several pilot experiments have been initiated along the Dutch coast. Also outside the Netherlands, projects for ecologically enriched seawalls are being developed. Based on the outcome of these experiments, the various designs are being improved continuously.
Water retaining pool in a dike, to enhance biodiversity
Here we consider the following types of structure enrichment:
- Soft Eco-Levee: Replacing the traditional 'hard-cover' design, the Soft Eco-Levee is in essence a safe dike constructed entirely of sediments. Added stability and wave dampening may be provided by deliberate introduction of vegetation such as saltmarsh vegetation, reeds, shrubs or trees.
- Rich revetments and foreshores: This concept aims to create highly variable habitats in the intertidal and subtidal zone of structures, utilizes a variety of different materials, gradients and shapes.
- Biodiverse hard substrates: The intertidal region of a seawall represents a very stressful habitat. Biodiverse hard substrates applies complex concrete tiles attached to seawalls can enhance their biodiversity.