Case

St. Anna’s Square: A multifunctional cloudburst solution

Couldburst protection at St. Anna's Square in Copenhagen provides green oases.

Cloudbursts and heavy rainfall hit Copenhagen and its surroundings more often than ever before. We need new and innovative solutions cope with torrential rainfall. HOFOR’s cloudburst protection at St. Anna’s Square is one example of such a solution.

The future demands innovation

We get more rain and we get rain more often today than we did just 15 years ago, and weather patterns are becoming increasingly erratic. The sewers and drains HOFOR laid in the underground to cope with rainwater and effluent are simply inadequate.

In recent years, HOFOR has therefore installed new cloudburst protection throughout Copenhagen and the metropolitan region to prepare the capital city for increasingly changeable weather conditions. Common to many of these solutions is that they do not only channel rainwater away, but also create new green urban spaces.

A new, underground cloudburst system

St. Anna’s Square in central Copenhagen and the surrounding historical district have been hit hard by flooding in the wake of cloudbursts. This low-lying area is encapsulated by solid building masses. The raised quay surrounding Ophelia Square prevents rainwater from draining from the St. Anna’s Square into the sea.

When the City of Copenhagen embarked on restoring St. Anna’s Square, HOFOR decided to construct a new underground cloudburst system under the square. Large underwater rainwater drains the full length of the square were constructed to collect rainwater from the roofs and square itself. The surface of the refurbished square was sculpted to resemble a bowl that quickly channels water away from its façades, down towards Kvæsthus Square and out into the sea.

Cloudburst protection provides green oases

The green space between the trees on St. Anna’s Square functions as a basin that, in the wake of torrential rainfall, channels rainwater from a large area around the square out to sea. However, the square has more than just the one function.

While the rainwater in the basin keeps the lawns, flowerbeds and trees luxuriant, the low walls around the perimeter of the low-lying green areas on St. Anna’s Square function as seating. The square functions – come rain or shine!

A 3VAND partner

We are an active partner in 3VAND – a strategic collaborative partnership consisting of the leading water utilities in Denmark: HOFORBIOFOS, Aarhus Vand and VCS Denmark.

About author

HOFOR  is the largest utility company in Denmark in our core business areas: water supply, wastewater management, district heating, district cooling and gas supply. We also build wind turbines. We focus on sustainable supply, renewable energy, adjustment to the climate changes and improved handling of extreme rain. The aim of our activities is to create sustainable cities - in cooperation with municipalities, other companies and our customers.

Primary contact
Astrid Skotte

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