Ignore the elephant in the Itchen at our peril

There’s a young elephant having fun splashing about in the shallow waters of the river that rushes through our City. We know that one day in its long life the beast may wake up with a headache and swamp Winchester’s low-lying streets. Fending off this disaster is beginning to resemble the blind leading the blind because those responsible for flood defences cannot bring themselves to mention the elephant of climate change.

Winchester School of Art, 2014

This window on this folly was opened by a front page 750-word story in the Hampshire Chronicle about the spiralling cost of the North Winchester Flooding Alleviation Scheme. This is a series of defence installations guided by technical modelling of the future interaction of global warming, rainfall and river levels. I was irked that the journalist failed to make a single reference to climate change. Then I found the same oversight, less forgivably, in his main source, a 9-page briefing for the City Council’s December cabinet meeting.

The last straw came last week when the portfolio holder for the Conservative-led Council issued a reassuring statement about flood defences that referred rather quaintly to “the unpredictable nature of the weather.” It was beginning to feel as though the burghers of the ancient capital of England had adopted the Trump administration’s notorious order to remove the phrase “climate change” from all websites and press releases.

The truth may be closer to bad habits than Orwellian edict, but Councillor Brook might usefully refer to the UK’s 2018 National Adaptation Programme which warns that “an extended period of extreme winter rainfall in the UK is now about seven times more likely than in a world without human emissions of greenhouse gases.”

It matters for so many reasons that climate change should be embedded in the language of the serious problems that it’s creating. This minor episode in Winchester illustrates my point to a surprising degree.

First, if climate change is the reason why traditional flood defences require significant upgrading, then the assumptions about its future impact should become a headline consideration. This has not really been the case in the various technical reports submitted to the City Council since 2014, when the Itchen rose to unprecedented levels.

Guidelines issued by the Environment Agency for climate change allowances in flood risk assessments were updated in 2016, offering regional analysis. The guidance for the South of England is to increase the normal variability in peak flow of the river by 30%-35% for 100-year projections of climate change.

An Arup report linked to approval of the Winchester project in 2017 adopts a 20% climate allowance, without reference to its source. Earlier reports dating from 2015 used 30%. The 2017 report does however recommend that “any new designs should consider the current climate change guidance,” presumably a reference to the 2016 government update.

There’s no evidence that this advice has been taken up. Greater willingness to represent the programme as a response to climate change might add pressure to examine the modelling assumptions more closely.

The second imperative for greater transparency about the cause of flood risk relates to finance. Winchester’s funding strategy for the current phase of flood alleviation has been to dip into the Community Infrastructure Levy, currently to the tune of £800,000 out of the total estimate of £1,250,000.

Water Lane flood defence

The CIL is a levy paid by developers on receiving planning permission. Local authorities are expected to spend the proceeds on “infrastructure that is needed as a result of development” such as roads, schools, hospitals and green spaces. “These flood defences are exactly the type of infrastructure challenges that CIL was designed for,” says Councillor Brook. She may be challenged on this assertion by villages in the District seeking to soften the blow of unwelcome housing developments with alternative ideas.

The reality for the City Council is that climate adaptation is not a sideshow relating to flood risk; it’s going to pop up everywhere and it’s going to be very expensive. In its section on infrastructure, the UK’s 2018 National Adaptation Programme says it all:

Climate change risks should be embedded in everyday work……resilience to extreme weather and climate change should also form part of every authority’s capital and maintenance programmes as well as their decision making processes

The sooner that projects are openly labelled as climate adaptation or resilience, the more likely a holistic climate funding strategy can emerge.

The third advantage of calling a climate spade a climate spade is the most obvious. Climate resilience demands joined up thinking, impossible if the tag is withheld. The North Winchester scheme aims to protect buildings in streets that would be affected if the river burst its banks. Inexplicably, it overlooks a building standing astride the river itself, barely 100 yards from the new sluices. The modelling charts are cut off at the end of Water Lane, just at the point where the water enters the City Mill, one of our heritage treasures, painted by Turner in its early days, now in full working order and a major tourist attraction.

Winchester City Mill

The issue for the Mill is not whether the river overflows the defences but the absolute level of the water forcing its way through its arches. In raising the river defences with a dwarf wall along Water Lane, the flood scheme contemplates a higher level of water, inadvertently threatening the Mill. The Council’s claim that its scheme will “help protect the (Mill)” is not substantiated because there is no reference to it in the technical reports.

The National Trust, as owners of the City Mill, carries some responsibility for this apparent misfortune, having taken almost five years to progress beyond emergency repairs to full structural analysis. Nothing could convey the hairs-breadth escape for the City in 2014 better than the structural reports by Ramboll in the current planning application for essential strengthening of the building. They conclude that the City Mill had been “at the point of collapse.”

The proposed engineering solution is ingenious but the stress modelling assumes a river level equal to that experienced in 2014. When Ramboll ran a model with a future climate allowance, similar to that for the flood defence scheme, it concludes that the “additional flood load overcomes (its new) flood protection measures.” Ramboll refers to “key remaining work: Investigate if and how resistance to the 900mm higher floods can be achieved.”

There’s a muddle brewing here, suggesting very basic questions for the promised period of public consultation. But the essential first step is to banish the elephant from the Itchen, and embed climate change, adaptation and resilience within the risk management discourse, where they belong.


Additional funding agreed to protect Winchester city centre from flooding – City Council news item

Winchester City Mill ‘likely to collapse in a flood’, report reveals, from Hampshire Chronicle

December 18th Cabinet Paper :Winchester Flood Relief Scheme (Durngate) Phase 2