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Viewpoint Alex Stephenson

SUDS law - Sustainable drainage systems must be at the centre of flood prevention.

The House of Commons' Environment, Food and Rural Affairs Committee last week made the strongest call yet for a more joined-up approach to tackling what it calls the "confused and chaotic" management of surface water drainage in the UK.

Its findings, after an examination of flooding in England and Wales, strongly echo the initial conclusions of Sir Michael Pitt's inquiry into last year's devastating floods and the current industry consultation by the Department for Environment, Food and Rural Affairs (Defra) as part of its Future Water strategy.

Two-thirds of the 2007 floods were the result of surface water flooding – urban deluges that flooded over 44,600 homes, with a total bill in the region of £3bn.

The committee has highlighted the urgent need to establish new local authority-based drainage authorities to own, co-ordinate and connect surface drainage systems more effectively within the entire water infrastructure. This is an extremely welcome move – there are currently too many bodies responsible for surface water management in the UK.

With the Environment Agency in an over-arching role, a new kind of agency based within local authorities would bring focus. This new framework would also bring the UK into line with other major European countries and keep us on track for the "source to sea" philosophy embedded in the European Water Framework Directive. We will need to work hard to develop the essential engineering skills to make these agencies a long-term success.

The committee has also shown its support for much more widespread use of sustainable drainage systems (SUDS). To achieve this will mean tackling the serious misconceptions about SUDS.

One of the guiding principals of sustainable drainage is to replicate the pre-developed site run-off hydrograph and deal with surface water as close as possible to the point of falling (the source), using the most appropriate means and technologies.

But in trying to achieve the required amenity value, many planners, developers and even water companies interpret SUDS as "natural" above-ground solutions such as swales or ponds. These solutions can have economic limitations for developers, and can often lead to perceived health and safety concerns.

For the principles to be truly adopted a best management approach is required, using the full SUDS toolbox of techniques to select those most appropriate for new and retrofit applications, from natural methods and proprietary technologies, including underground infiltration, storage and attenuation devices. Full account also needs to be taken of effective control and removal of sediments and pollutants – again at the earliest stage.

It's 15 years since Hydro International published Urban Drainage: The Natural Way, highlighting the importance of source control and SUDS. Those principles still apply, and we hope the measures taken to tackle surface water drainage will go back to those first principles. In short, the three key tenets of sustainable drainage – quantity, quality and amenity – remain valid.

Alex Stephenson is director of Hydro International's Stormwater Division.

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