Water plazas:
public spaces as storage for surplus rainwater
Multifunctional and easy to implement
It rains more often and more heavily in the Netherlands. The water has nowhere to go, particularly in densely populated urban areas. Sewers overflow and streets flood. Towns and cities are seeking ways to deal with flooding in a sustainable way.
In almost all towns at the moment, relatively clean rainwater goes straight into the sewers where it mixes with (dirty) sewage water. If the sewer systems become overloaded during heavy rainfall, the polluted water overflows into the canals, with all that that implies. Design agency VHP, a Royal Haskoning company, has found an urban development solution—the ‘water plaza’—for the (temporary) storage of surplus rainwater. Water plazas in the middle of residential districts will soon be collecting the water, temporarily, close to the source. ‘This requires no radical alterations in the structure of the town,’ say urban designer Florian Boer and engineer Willeke Vester. ‘It is only a question of adapting our public spaces. Money that is normally spent underground is now put to work above ground on the construction of these multi-functional water plazas.’
All kinds of facilities
Of the six types that have been developed, Florian prefers a complex plaza with various forms of water storage. ‘For example, you can combine a plaza with sports facilities, underground storage and an information point for residents. Ninety percent of the time the water plazas would be dry and in everyday use as public spaces. You could skate, play basketball, walk or sit,’ says Florian. When it rains heavily the rainwater runs along fixed routes to the plaza in a controlled and visible way. Initially only the gutters fill up, then lower lying parts of the water plaza with a few centimetres of water and when there’s really heavy rainfall the plaza changes function and becomes a storage basin. After the shower the water infiltrates slowly into the ground or is drained off to open water later.
Cleaner canals
Politicians, water boards and Dutch local authority health services are enthusiastic about this new form of water storage. ‘Using water plazas puts less strain on sewage systems. Our aim is to gradually build up the application from this principle, so that in due course all the water drained into canals will come from water plazas and that will improve the water quality.’ VHP realizes that practical objections will have to be overcome. For a start, how do you get the neighbourhood to learn to live with a water plaza like this? How do you teach small children to deal with the dangers of a water plaza? ‘The safety aspects are just a question of getting used to it,’ says Florian. ‘There are already a lot of areas of water in Vinex districts, and a lot of interest in our plans has been shown from abroad. But this is too early. Initially we’re going to build a water plaza in Rotterdam South. And when we’ve got over the teething troubles we will have an excellent, sustainable export product with countless possibilities.’
Contact: Willeke Vester
+31 (0)10 4520 744
w.vester@royalhaskoning.com
