Nature can help when extreme weather hits

Our cities and rural areas cannot always cope with all the water from cloudbursts, prolonged rain and rising sea levels. Cellars, sewers and harbor piers are flooded, and it is obvious to suggest dikes, larger sewer pipes and rainwater basins as solutions. 

But we can get more out of choosing solutions that involve nature itself; these are the so-called nature-based solutions.

The researchers behind SDU's new elite center, Aqua-NbS (Elite Centre of Aquatic Nature-based Solutions for Climate Change adaptation and mitigation) know this, and now they have been granted DKK 10 million to pave the way for nature-based solutions to be further scaled up in Denmark. 

The elite center will follow 11 demonstration projects and also gather input and experience from the authorities, landowners, volunteers and NGOs involved. 

An example of a nature-based solution is to allow vegetation and underground absorb excess water instead of collecting it in, for example, a concrete basin or letting it flow over concrete and asphalt directly into waterways or the sea. 

Such areas already exist in nature; it's the salt marshes. The soil of salt marshes can absorb water and thus prevent flooding. Water seeps only slowly through the salt marshes and their small channels and therefore it flows slowly into fjords and creeks. Along the way, particles and nutrients from the water are absorbed by the salt marsh, so that the water is cleaner and less nutrient-rich when it reaches fjords and creeks.  

- Salt marshes are a classic, nature-based solution. We have removed many of Denmark's original salt marshes, but we can restore them – and should also do so in more places, because they can really help, Cintia Quintana believes.

New fjord landscape in the town center of Vejle 

In the Danish town Vejle, where there is a risk of flooding from the fjord, the municipality is working on protecting the low-lying town center from flooding. One of the ideas is to establish a nature-based protection facility, that runs as a wide zone between water and land. It will not only protect the town from flooding, but the aim is also to increase the biodiversity under and above the water.  

By creating a membrane facility, made of mainly nature-based materials and with great variation in surface and texture, the construction may create new biotopes for plants and animals.  

- The core of the idea is to expand the zone between water and land and create a bufferzone that works along the same principles as the original salt marshes. If this project can also contribute to more biodiversity in our inner fjord, it is a bonus, said Lotta Tiselius, an architect and project developer in Vejle Kommune, and continues:

- On top, the citizens of Vejle also get a new recreational area, where they can experience the dynamics of the sea up close.

 

Are there other solutions than the classical concrete wall? 

- The optimal nature-based solutions consist of coherent measures, where you plan the water's path from the catchment area through catchment basins and on into the waterways. It will be one of our tasks to create guidelines for this, said Cintia Quintana. 

Lotta Tiselius from Vejle Kommune adds:  

- It makes a lot of sense to develop the future’s nature-based solutions in towns and municipalities in collaboration with experts like Aqua-NbS. We don’t really have that many good examples of nature-based solutions yet, especially not in urban coastal environments, which is what our project is about, she says and continues:

- We try to find other solutions than the classical concrete wall to protect us against the water – for that we need to work with experts in especially biology over and under the water. For Aqua-NbS, there is a value in seeing how demonstration projects are planned and constructed in places where they have a purpose.