6 January 2014

How Suds can stop the floods ....

After our wet Christmas we have been wringing in the new year with more than a week of flooding in England, Scotland, Wales, Ireland and even the Isle of Man .  Further deluges are forecast for the next few days, and the Met Office has warned there's no end in sight, with more depressions expected.

Yet last week marked the fourth new year since legislation was passed to tackle one of the most important and intractable causes of floods, which ministers have so far failed to bring into effect, protesting that they do not want to implement it in haste. 

This is on top of the disclosure that hundreds of staff at the Environment Agency could lose their jobs.  This suggests an extraordinary complacency, even by Whitehall standards.

The laid-by law aims to allay the impact of 21st century conditions on 19th century attitudes and infrastructure. We have sought to remove rainwater as quickly as possible, speeding its passage back to the sea through pipes and sewers, culverts and canalised rivers.  Natural draining systems have given way to engineering.

But as populations have increased and construction has spread, this  infrastructure has become inadequate.

It's made worse by new developments, such as front gardens being paved over for parking, causing water to run off faster.

Rainfall has risen 5% in Britain in the past 20 years and, more significantly, heavy bursts are increasingly replacing our archetypal drizzle, something expected to accelerate with climate change. 

Much of the massive flooding of 2007 - described as Britain's greatest even civil emergency - was caused by just such factors.   In Hull, for example, a month's rain falling in 24 hours overwhelmed even a relatively modern drainage system, flooding 7,200 homes and 1,300 businesses.  

Even when the sewers do cope, increased flow causes rivers to break their banks and raw sewage to surge out of some 14,000 storm overflows in England alone.

a swale
So attention is increasingly returning to measures that mimic the natural processes; reducing the amount of water reaching the man-made systems.  Boringly entitled sustainable draining systems (but more attractively acronymed as Suds) slow the flow, store it and encourage it to seep into the ground.  Suds include 'green' roofs planted with vegetation, permeable paving allowing water through to the soil below, grassland depressions called swales that carry water off into ponds, and even garden water butts.

Typically they cost less than half as much as traditional draining systems and far less than the flood defences rerected to safeguard communities, essential though both continue to be.  And they can improve areas and property values by encouraging wildlife and adorning landscapes.

Financial incentives drove up numbers of green roofs in Germany 19-fold in just 12 years.  In Melbourne, Australia, a five-year scheme is establishing 10,000 'raingardens' - flower and vegetable beds underlain with sandy soil to help water filter away.  The Augustenborg suburb of Malmo in Sweden, has been relieved of reguolar flooding by a network of green roofs, swales, ponds and mini-wetlands.  Several cities in America, including Portland and Philadelphia, have established similar natural infrastructure, while the city of Aurora in Colorado so reduced run-off that it avoided building a costly new plant for treating waste water.

There are some good Suds in Britain: a nature reserve near Doncaster, for example, absorbed 200,000 cubic metres of floodwater in 2007, saving thousands of homes from inundation.  But they have not spread widely, for the lack of legislation.

In 2008, new rules meant that planning permission was required to lay impermeable paving in front gardens.  But the big breakthrough for England and Wales was supposed to have been offered by the 2010 Floor and Water Management Act, which, amongst other things, allows new developments connection to drainage systems only once they have been passed by a body overseeing Suds.

Nearly four years on, that provision has yet to be brought into force.  Ministers first pledged - and failed - to do so by October 2012, then by April last year.  Their most recent target is April this year.

A Commons committee has repeatedly registered its 'great concern' and 'dismay; at the delay, but to no avail.  and even when it does come into effect, it will only tackle a tiny part of the problem, since it will address only new developments, which make up less than 1% of the built estate.

Surely, as a nation, we should be good at coping with rain? But familiarity seems to have bred complacency.  The consequences, you might say, are flooding in.

From an article in the Telegraph by Geoffrey Lean, January 2014.

See: http://www.groundwateruk.org/Groundwater-issues-SUDS.aspx
and also: http://noels-garden.blogspot.co.uk/2012/08/olympic-glory.html

No comments:

Post a Comment