Cities of the future
Cities of the future will have to be more prepared for the danger of flooding, while at the same time be more efficient in the use of drinking water. The world as a whole is in dire need of sustainable water management, according to SWITCH, a joint project of the European Union and 32 partner organisations."At this moment over one billion people do not enjoy a service of drinking water. More two and a half billion people have no access to sanitation facilities."
So says Professor Huub Gijzen, Scientific Director of SWITCH, an acronym for Sustainable Water management Improves Tomorrow's Cities' Health. SWITCH searches for new ways to improve water efficiency, to protect cities against floods and to make clear to governments that a new water management policy is necessary to prepare cities for the future.
Save drinking water
It's time for a change in the way we use water in our cities, warns Professor Gijzen. But, he says, old habits die hard. Here in the West, for instance, we've grown so accustomed to having clear drinking water aplenty that we use it for very inferior purposes:
"At the extreme end of the scale I'd like to point at the flush toilet where we use drinking water, crystal clear with the only purpose to transport excreta out of the city. And what happens when this wastewater gets into the environment? 85 percent of all wastewater produced worldwide is at this moment contaminating our water resources. That leads to pollution but it also leads to very serious health treats."
Mega-cities
In the future, problems will only get worse because of the growth of mega-cities such as Beijing, Shanghai or Mexico City where more than 10 million people live huddled together.
"Those mega-cities create an enormous disruption in the countryside and the water balance. In a city everything is paved with tarmac and when it rains the water can't go anywhere, and so flooding occurs. That's why it's important to re-establish the natural situation. We have to become more conscious of space in a city: create open spaces that can retain rain water and that can function at the same time as recreation area - or nature area."
Dutch practice
In the Netherlands sustainable use of water is
obligatory by law. The
latest findings and solutions are tried out in new housing development
projects. In the centre of the Netherlands, for instance, an ingenious
system of ditches, canals and wadis (a retention area for rain water)
is used to save the new neighbourhoods from flooding after heavy
rainfall, explains Wibo de Graaf of engineering office Grontmij."The neighbourhood is set up in such a way that it seeks balance.
The wadi, at first sight a low lying patch of grass in the neighbourhood, combines a nice bit of greenery with water management. Previously, all rain water used to go straight into the sewage system. Now the water runs through drains to the grass plot. When it rains heavily the wadi is completely flooded. The water then gradually seeps into the soil and the advantage is that the sewage system can be a lot smaller."
Professor Gijzen sees more technical solutions
ahead.Vacuum toilets, like the ones used in airplanes, do not use any water and should be adapted, he says, for the home situation. Even in mega-cities, where space is very limited he sees possibilities for the implementation of 'green zones'. He's convinced it's not too late to turn the tide.
"Infrastructure has a life-time of 20 to 40, 50 years and we see regularly, also in Europe, that whole areas in cities are reconstructed - those are the opportunities to start doing things differently and make cities again pleasant to live in and in balance with their environment."
Liesbeth de Bakker and
Willemien Groot 12-05-2006
See also
The biggest city in the world – Chongqing
Beijing cuts local taxes and Shanghai house boom ends
Access to water not yet a human right
Water desalination