24 November 2009

Slow water

This is a term that I had not heard of before but it was mentioned on this morning's Today Programme on Radio 4. The interviewee had not heard of it either. But we all know what its about - the slowing down of water runoff during heavy rain to help reduce flooding. Sadly, no amount of  flood water management would have saved Cockermouth from 2 metre high flood waters, but its something that urban planners need to think about as monsoon rain becomes more common in the UK!

So what can we do to slow down the run-off of water into drains and water courses. Well quite a lot. Starting with green or living roofs that take up a lot of water and release it slowly. Water can then be directed from roofs into temporary storage areas. This way it does not get contaminated with pollutants from the street and can be put to more use. The sedum roof on the left is on the Norfolk Wildlife Visitor Centre at Cley Marshes. Not only do the plants take up CO2, but they absorb water and provide excellent insulation. Any water draining off is collected and stored.

On the ground the pavements can be permeable - that involves using surfaces that allow the water to penetrate rather than run straight off into the drains. A couple of years ago designers at Hampton Court has some great ideas for front gardens that has permeable surfaces to reduce run off. They used gravels, grills, and permeable hogging to create an attractive, yet totally practical urban front garden. 

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