Technology

The more than seven million drivers and their passengers crossing the Sound via the Øresund bridge and tunnel each year can now rest assured a storm surge will not leave them stranded along the way. Øresundsbro Konsortiet is protecting the four-kilometre-long tunnel against a surge. When the current projects have been completed in 2025, the tunnel part of the Øresund link will be able to withstand a 10,000-year storm surge projected up to 2050. The Øresund link between Denmark and Sweden was designed to withstand a 10,000-year storm surge when it was first inaugurated in 2000. But climate projections have changed since then. According to new climate models, we can expect to see more frequent and more powerful storm surges. The current projects therefore involve building new dikes and a concrete wall to protect the tunnel stretch of the link.

In the Municipality of Assens on Funen, three new retention ponds are keeping the town of Tommerup Stationsby dry-shod, even after persistent and heavy rainfalls. The three lakes - together known as Tallerupsøerne - are the largest climate adaptation project to date on Western Funen. The lakes are interconnected via meandering channels, and during heavy rainfall the three lakes become one large lake able to retain as much as 22,000 cubic metres of water. When the lakes fill up with water, the water is led on via a controlled pipe system into the Brende Å watercourse. The lakes were established on a 7-hectare land area acquired for the project by the local public utility company, Assens Forsyning A/S. The land was already gently undulating. The project entailed digging the hollows deeper and adding the soil dug up to the hilly parts, thus accentuating the undulating terrain. The local inhabitants of the area have been actively involved in creating the new landscape and recreational area surrounding the lakes. The lakes were designed to withstand a five-year rainfall event but have proven capable of withstanding more.

The local district heating company, Høje Taastrup Fjernvarme, pumps up groundwater, sends it, and the energy it contains, onwards through a heat pump and into the district heating pipelines; thus killing two birds with one stone. An excellent business case is what originally prompted Høje Taastrup Fjernvarme to start using groundwater for heat production. However, the process also lowers the high groundwater levels in the area. Previously, residents in the area experienced frequent flooding of their basements because the water table has risen by several meters over the past years. The cooled water is pumped into the Mølleåen river, which will significantly improve the living conditions for flora and fauna. Dispensation from the Danish Energy Agency was required, because the area is otherwise designated for heat supply from CHP.

In 2011, the greater Copenhagen area was hit by a massive cloudburst event. Helenevej, a small cul-de-sac to the larger Bülowsvej road in Frederiksberg Municipality, was flooded. Today, the road has new climate-friendly road surfacing designed to absorb large amounts of water.

The City of Aarhus has established a sluice at the mouth of the city's river, Aarhus Å. The sluice protects central parts of Aarhus against flooding. The construction serves two purposes. Firstly, four sluice gates will protect the city against intruding seawater during high sea levels, and, secondly, six powerful pumps will pump water away from the river and into the sea during cloudbursts. The sluice can pump as much as 18,000 litres of water per second from the river and out into the sea. In order to provide further protection for the low-lying parts of the city during high water levels, the two streets, Havnegade and Europaplads, as well as the area around the sluice itself, have been raised. The construction costs totalled DKK 46 million. A traditional solution, with underground retention basins to retain the water, would have cost ten times this amount.

In order to protect the area around Slotsholmen, a small island district in Copenhagen city centre and the seat of national government, against seawater during extraordinarily high water levels, the quay walls around Frederiksholms Kanal have been reinforced and raised over the years. However, the intention to protect the city against seawater has had the unfortunate consequence that during heavy rainfall the rainwater cannot run out into the harbour. Copenhagen experienced this during the intense cloudburst in the summer of 2011, when many buildings around Slotsholmen stood under water. Steps have now been taken to prevent this from happening again. During very powerful rainfall events and cloudbursts, the rainwater is today directed via grates along the sides of the road and via underground drains to an opening in the quay where the rainwater runs out into the harbour. At the outlet there is a non-return flap valve, which ensures that the water can only run out and not in. During very high water levels, the valve shuts and flooding is prevented.

The new Novo Nordisk headquarters in Bagsværd on the outskirts of Copenhagen stand out in more than one way. With green roofs, water reservoirs, well-conceived natural areas and a large underground gravel cushion, the group's new domicile will retain all rainwater on site. "Keep expenditures at a minimum by involving the public authorities early on in the process!" This is the advice from the group.

When the new Central Denmark Region hospital in Gødstrup stands ready in 2020, it will include an innovative and sustainable concept for managing surface water and rainwater that will transform the hospital into a resource.

The Municipality of Dragør includes some of the most vulnerable land in Denmark with regard to sea level rises and storm surges. Climate change adaptation is important not only for the municipality itself but also for the neighbouring municipality, for nature management in general, as well as for the Metro, the Øresund link and the Ørestad urban district. Collaboration, communication and innovative thinking are therefore vital for climate change adaptation measures regarding Dragør's vulnerable areas.

Lindebjerg school is a small village school near Roskilde. It has gradually come to be known as the 'Climate School'. An ambitious project with local drainage of rainwater (LAR) is teaching pupils to see water as a resource through learning and playing, and the effect is now spreading like ripples on a pond.