rains and drains

From January through to April this year there was a major exhibition at the Danish Architecture Centre under the title The Rain is Coming. It looked at climate change and the impact that will have on the architecture and planning of our cities. The conclusion was that climate change is happening already and that planning has to take that into account now but it can be seen as a way of making positive changes.

It is fairly clear that for Denmark the climate changes will mean more rain and more intense storms and that drains and roads will not be able to cope with the sudden inundation of water. I have actually experienced this … shortly after I moved to Copenhagen there was a massive rain storm; the street drains backed up and the road and pavements were flooded and water streamed down into cellars. Further along the street many of the buildings have semi basements so there is half a flight of steps up to the entrance and main floor but short flights of steps down to a semi basement that in many buildings are used for shops or workshops. Many of these businesses were severely disrupted by the flood … water had to be pumped out, property dried out and in many cases floors relaid and walls re-plastered. At least one of the businesses is still closed a year on.

There are straightforward solutions that are being implemented throughout the city and in new developments. Many streets are being dug up to install more robust drains to replace simple gutters. These have a large buried concrete channel covered by a continuous grill rather than a gutter that drops water down into a drain at intervals.

In some areas, permeable surfaces are now being installed so water will percolate down between cobbles or down through artificial playing surfaces on sports areas rather than sitting on the surface or flooding across to overloaded drains and well-planted ditches or hollows will be attractive green features for most of the year but will become streams or ponds when there is heavy rain.

Several major drainage and landscape schemes are now under way around the city. With so much land covered with buildings or roads there is less and less chance of water soaking away but if it is allowed to run straight into drains then they fail and can also compromise or damage the sewerage system with obvious consequences. The schemes are designed to hold back rainwater so that it can be released into the drains in a controlled way after a storm.

For the full article and photographs go to the Copenhagen site