Biotopes help Copenhagen plan for a rainy day

#Denmark #Ecological

Copenhagen-based design practice SLA wins the Nordic Built Cities Challenge Award for a landscape proposal that uses natural processes to defend cities against natural disasters.

As the world’s weather patterns appear ever more unpredictable and subject to extremes, the search is on for urban design solutions to help protect cities from the resulting floods and heatwaves. Driven as much by local municipalities as by national governments, a number of design initiatives, workshops and competitions have emerged around the world, promoting urban environments that are resilient and climate adaptive. A good example is the Nordic Built Cities Challenge.

The 2016 overall winner is a proposal from Danish urban development consultancy SLA, whose proposal for the Copenhagen district of Nørrebro presents an ambitious plan to manage an increase in frequency and extent of sudden and heavy rainfall. The submission focuses on a long slice of the city, starting at Hans Tavsens Park and stretching along Korsgade, down to Peblinge Lake, and is distinguished by two key elements.

Firstly and most importantly, the proposal establishes an innovative approach to watermanagement. Three distinct approaches to watermanagement are proposed. Rain water will be collected in tanks across the entire area for use by by local residents. That is the everyday component of the design proposal.

In response to heavy rainfall, Hans Tavsens Park will be fitted with 18,000 cubic meters of ‘delayed volume’ at ground level, so that storm water can be purified and delayed before discharge via discharge pipes into the lake. When storms threaten to flood, rain water will be directed at ground level along a retrofitted Korsgade, down to the Peblinge Lake.

This is not, however, simply an civil engineering solution: it is also an ecological one. This kilometer of city, from the park to the lake, will serve as an elongated, circular water purification system, purifying not only the rain but also the lake. Combining natural biotopes with advanced natural filtering and pumping techniques, this system will purify rain water, removing nutrients and phosphorus, as well as suspended solids and metals. When not dealing with storm and rain water the system will be pumped with lake water, as a year-round water feature that simultaneously cleans the lake.