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THE CLIMATE CRUNCH

Who should be responsible for managing flood risk as climate change pushes the issue further up the political agenda?

Flooding in the UK is nothing new, and nothing we do not expect. But last year, the big change was that the flooding came in the summer, it came very quickly, and it was more devastating than usual.

Association of British Insurers (ABI) climate change policy advisor Swenja Surminski, said the summer floods were "the most costly natural disaster in the UK. Four years of claims came in this short time," she says.

Before last summer, ABI modelling had suggested that the costs of a severe inland flood would be less than the £3bn cost of the summer 2007 floods.

Clearly the rainfall was exceptional, and we were simply unprepared for the scale and breadth of devastation that fell on the UK, particularly in Hull, Gloucestershire and Sheffield.

Unfortunately, while the summer floods were without question an extreme event, there is the possibility that such events may not be classed as extreme in the future. Indeed, only last week we saw vast swathes of northern England hit hard by more, serious, flooding.

Tyndall Centre for climate change director professor Andrew Watkinson is a director is and contributor to the United Nations Intergovernmental Panel on Climate Change (IPCC) report in 2007.

"Science agrees that climate change is happening," he says. "The IPCC has 90% certainty that anthropogenic [man-made] greenhouse gas emissions is the cause. Recent modelling suggests a 1°C to 6°C rise in the next 100 years."

However, while models for some parts of the world are easier to predict, the UK is, unfortunately, a special case. As it is located between two weather systems.

"Modelling puts the UK on the border of higher and lower rainfall, so predictions are difficult," admits Watkinson. "Drier areas should become drier, wetter areas wetter. But extreme events should be more frequent. The events of last summer fit the model. Just about," he says.

The IPCC is running 20 different climate change models simultaneously. Most show that there will be wetter winters and drier summers.

To rein in the effects of climate change, most climatologists agree that the quantity of CO2 in the atmosphere – currently around 385 parts per million (ppm) – should stabilise at no more than the European Union's target of 450ppm. Most climatologists also agree that this target is unrealistic, but that 550ppm could be achieved with some effort.

"At 450ppm we could limit average temperature increases to 2°C," Watkinson says.

He adds that there is an overemphasis on the 2˚C as temperatures are expected to rise by more than that.

More CO2 in the atmosphere will make the atmosphere warmer, creating more rain, and will also raise sea levels. Over the coming 100 years, sea levels are expected to rise by 400mm to 900mm due to the thermal expansion of the water. Melting polar ice would further increase this, but this is difficult to model.

Another difficult area is rainfall. "The models cannot predict rainfall with precision," says Watkinson. There are ball-park figures and that is what you have to plan with," says Watkinson.

One area of action where there is broad agreement is the need to sort out legislation governing surface water and make a specific body responsible for it.

Contenders to take responsibility for surface water include the Environment Agency, local authorities, local government funded Internal Drainage Boards and water companies.

University of Sheffield professor of urban drainage Richard Ashley, says that the debate about who should take responsibility for surface water is neither a mystery nor new. "England has the most complex institutional arrangements probably in the world. We are addicted to consultations and reviews.

"First came the ICE's Learning to live with rivers document, published in 2001, the government backed, but independent, Foresight Future Flooding report in 2004 and now Pitt [Sir Michael Pitt author of the soon to be published government report on the summer floods]– they are all saying the same thing. We have too many frameworks, and we need bottom-up, local solutions," he says. Ashley believes that local authorities should take charge, as they have local knowledge and know local needs.

The Environment Agency has volunteered to take charge of surface water, and according to Association of Drainage Authorities chief executive Jean Venables, Internal Drainage Boards already do much of this work, but need more power.

But there is debate about who should fund flood prevention. "Since people up the hill contribute to the flood down the hill, why do only those living in flood-prone areas pay drainage charges? We all contribute, so we all should pay," she says.

United Utilities strategy planning manager, Brian Morrow proposes a mixed approach. "There are too many people involved now. Utility companies do not know what their involvement should be. Nobody has responsibility for draining surface water – there is lots of ambiguity."

Morrow says much of this comes from the Water Industry Act, which is based on legislation going back almost 35 years. It requires companies to "effectually" drain an area.

The Environment Agency should be responsible for rivers, watercourses and general bodies of open water, and the water companies should be responsible for all other urban drainage infrastructure, he says.

But it seems increasingly difficult to build sustainably. Sustainable Urban Drainage Systems (SUDS) have been touted as a way to manage surface water effectively, by regulating when rain water is released into rivers and streams.

But, SUDS are a good idea which has lost its way, says City of Bradford principal drainage engineer, Tony Poole.

"Ten years in, we need to re-launch it. Developers are unnecessarily contributing to surface water flooding by increasing run-off. SUDS legislation is working against us.

"SUDS is not a magic wand and there is no way to assess the quality of outflows, and there is high seasonable variability."

Venables says that SUDS can make a difference, "but they are effective in a system only if they are all empty to start with."

Venables believes the best solution is to build infrastructure into a development before you lay a brick.

She also points out that you do not have to be in a flood risk area to be flooded as water can pass through other areas on its way to the flood plain.

Environment Agency head of flood protection David Rooke wants to, "remove the automatic right to connect to surface water sewer," a sentiment echoed by Severn Trent Water sewerage asset manager Phil Gelder. Naturally, this would be a disincentive to develop in a flood plain.

Gelder also asks, "Should we separate surface and foul water like we did years ago? It is common sense and not beyond the wit of man.

"Taking surface water to treatment is daft. Should we have a phased retreat from flood plains? I think so."

Whoever is given the responsibility for surface water, the decision will be influenced by Pitt's report into the 2007 floods.

But there is still a chance Pitt could take his eye off the ball.

Venables says, "Pitt's interim proposals are very much focused on local authorities and emergency planning. I would like to see more on legislative arrangements for surface water."

There is a hole where responsibility for surface water should sit, and the legislation does need an overhaul.

Pitt's review gives us a marvellous opportunity to fix this.

FLASH FLOOD PREDICTOR
Combining the latest ultra fast two dimensional modelling techniques with high resolution digital terrain data has enabled consultant JBA to develop what are claimed to be the world's first national flash flood maps.

The maps indicate areas and properties vulnerable to flooding from extreme rainfall.

The maps are seen as the first step to addressing the risks posed by the type of rainfall experienced last summer. The maps can be used to ensure that further flood mitigation resources are focused in the high risk areas. JBA will use these maps to prepare Surface Water Management Plans and Emergency Response Plans, which will help government bodies prepare for increasingly frequent intensive rainfall.

Last summer's floods

13

Number of death linked to
the floods

48,000
Number of homes flooded

08
Motorways were closed

10,000

people were stranded on the M5 overnight

Pitt Review:
interim conclusions

- Greater coordination between public authorities is needed during flooding

- Water and power companies need to do more to protect vital infrastructure

- Flood warnings must be better coordinated

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