Commons Environmental Audit Committee adds its support to sustainable drainage systems

A failure by successive governments to implement sustainable drainage legislation has been lambasted by the Commons Environmental Audit Committee (EAC) in its latest review of Government flooding policy.

Flooding: inquiry looked at Government policy and assessed whether it was co-operating across all departments - image: Pixabay
Flooding: inquiry looked at Government policy and assessed whether it was co-operating across all departments - image: Pixabay

Severe flooding in December and January affected Wales, the north of England and parts of Scotland and Northern Ireland. Insured losses totalled £1.3bn. The floods prompted the EAC to launch an inquiry into whether the Government's approach to flood policy was "joined-up" and whether it was co-operating across departments.

Better catchment management - including major tree planting efforts - and the use of sustainable drainage system (SuDS) measures such as swales and rain gardens were recognised as key ways that flooding could be mitigated.

But the EAC report, published this month, found that "despite sustainable urban drainage systems being widely acknowledged to be an efficient way of dealing with surface water, successive governments have been reluctant to mandate them as the default option in new developments".

The latest instance of this was the Government's refusal to legislate for SuDS through the Housing & Planning Act, which the EAC said was "disappointing". Instead: "Government has kicked this into the long grass by commissioning another review. This is an issue that now requires action."

The Government's lack of a long-term strategic approach to flood-risk management has resulted in "knee-jerk" responses whenever disaster strikes and leaves communities at risk, according to Sue Illman, former president of the Landscape Institute and the Construction Industry Council's champion for flood mitigation and resilience.

"SuDS are recognised by the committee as an efficient way of dealing with surface water and this sends a call for action to the Government on the mandating of SuDS as the default option in new developments," she said. "It is the obvious long-term solution."

Under national planning policy developed following the 2007 Pitt review, new development must give priority to the use of SuDS. But the committee heard that so far uptake is "disappointingly low" with cost to developers usually cited as a barrier to implementation.

Environment minister Rory Stewart was asked whether it would not be easier to force developers to create SuDS "sponges" on housing estates rather than connecting to ancient Victorian sewers. He told the committee that while in many cases that is the smart thing to do, it is not always the most cost-beneficial intervention.

But Illman said SuDS are simple and relatively inexpensive as a way of preventing surface water flooding as well as supporting biodiversity and providing attractive landscapes. "Flooding is not a new phenomenon and it will occur again," she pointed out. "It is only wise that we as a country face up to it and put long-term solutions in place.

"We need a clear strategy from Government that provides solutions that are coherent and adaptable to local circumstances. That strategy needs to recognise the economics - that planted (bioengineered) drainage schemes, used at both the catchment and small scale, can make a significant contribution to preventing flooding, are easier to implement and cost significantly less. That way, we can do much more.'

Tree planting and other natural flood-alleviation techniques are working well in pilot areas such as Pickering, where leaky dams and upstream storage slowed the peak flow by 15-20 per cent and helped save the town from flooding in December. But the committee's report found the Environment Agency in particular is overly cautious about such interventions.

Stewart said a catchment-wide approach would be central to Defra's 25-year plan, from planting trees at the top of a catchment and restoring blanket bogs to allowing rivers to meander and relooking at bank-management techniques. But he said Defra has to work out what the "consequence of planting 1,000 oak trees in a particular location will be and how the cost benefits of that compare to other kinds of funding".

He added: "That is the challenge that I am facing day in, day out, to explain to people that it will be 25 years before these trees begin to have an impact - 50 years before they have a major impact. The root structure, gravel structure, flow structure, the way that the catchment can change in a flood event, modelling it and coming up with cost-benefit analysis that we can get anybody to agree on, let alone the public to sign up to, is challenging."

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