Climate change adaptation at Aarhus Docklands

Over the years, the location of Aarhus, next to the sea, has been of crucial importance to the economy and development of the city. It is also one of the reasons why the Port of Aarhus has flourished into a vast industrial port and is today Denmark's largest and busiest container port. Unfortunately, the port has also severed the contact between town and sea, an issue that Aarhus City Council has decided to re-examine.

In 1997, Aarhus City Council adopted a master plan which defined the framework for the port's physical development. As part of this master plan, parts of the docklands were to be redeveloped to create an attractive and vibrant district with both homes and businesses.

In 2007, the Municipality of Aarhus took possession of 100,000 m2 of the port area. This marked the beginning of the construction of Aarhus Docklands on the site of a former container terminal, Pier 4, which is the oldest of the Port of Aarhus' container terminals. The district will accommodate 7,000 inhabitants and 12,000 jobs, the vision being to create an attractive district of Aarhus City and a recreational link to the fjord. There are already development plans in place for much of the area, and the first residents were given the keys to their new homes in January 2012. Furthermore, all the buildings are being constructed as low-energy buildings.

Pier 4 is situated at the tip of Aarhus, where the city meets the bay. The closest neighbour is the Kattegat, with large expanses of deep water and several nautical miles to the nearest coastline. Therefore, the area is extremely vulnerable to rises in sea level and spray from waves. For this reason, when developing the site, the municipal authority raised the terrain by 0.5 metres to an elevation of 2.5 metres in order to take into account the rises in sea level that are anticipated over the next 100 years.

At the very end, towards the northeast and Kattegat, a 1.2 km-long promenade has been constructed with exterior coastal protection. At the most exposed corner, the contour line of the promenade has been elevated to 3.7 metres and then gradually reduced towards the land to 2.5 metres in line with the rest of the area.

A 10-metre wide belt of rock armour has been constructed as part of the promenade's coastal defences at an elevation of -0.5 metres below the surface of the water, off the promenade. The rock armour is only visible a few days a year at low tide. The rock armour breaks the waves out at sea instead of at the promenade. This reduces the impact of spray from the waves. Local fishermen and divers have also reported that the sea bed along the rock armour has become rich in wildlife, with, for example, lobsters and plants between the boulders.

As predictions of climate change and rising sea levels are subject to considerable uncertainty, the coastal defence solution around Pier 4 is an adaptable one. The rock armour off the promenade can be readily extended to provide protection against fiercer waves and more drastic rises in sea level if the forecasts for the future of our climate prove to be underestimates. In order to arrive at the right solution, the Municipality of Aarhus sought the assistance of external consultants to determine the design of the rock armour and the coastal defences.