It was a dark and stormy night...So I began my blog two years ago in December 2013 telling my engineer's tales of how climate change is affecting UK infrastructure through storms, floods and landslides. This week, as the COP21 climate negotiations in Paris have worked through many stormy nights (literal and metaphorical) to try and hammer out a deal, the ICE hosted the Triennial Summit with the American and Canadian societies of civil engineers, a conference about resilience, climate and meeting the infrastructure needs of the future for cities around the world.
A review of 2013/14
2013/14 was a bad winter for the railways, as I wrote about in more detail a few months later in March 2014, when it had been confirmed as the wettest three month period in UK history in some places. The railway at Dawlish was wrecked by ferocious waves caused by the St Jude storm's high winds, cutting off rail access to Cornwall and it was only reopened in time for Easter.
There were over 100 landslides on the rail network, including several places like the Hastings line where multiple incidents happened on the same line. A presentation by a rail engineer for Kent at the Yorkshire Geotechnical Group in May told a sorry tale of fighting the elements to get the lines reopened again, but in some cases it took many weeks because it was impossible to get materials in or out by rail where the line was blocked in both directions.
This was just one example of the cascade effect, where the failure of one piece of infrastructure makes other elements more susceptible. For example, what use is it having emergency generators to keep a hospital running if your staff and patients cannot get to it because the local transport infrastructure is flooded? What happens when your flood pumping stations require electricity to run but the whole area is without power due to wind damage to the overhead lines, or because a major substation is flooded? How can you run an airport when the motorway and railway which get staff, passengers and freight into and out of it are not available? These are just some of the stories in the DfT's Transport Resilience Review conducted in the aftermath of the floods, published in July 2014, demonstrating that our infrastructure systems are interdependent and vulnerable, and there is a particular need to identify and protect "critical points of failure" without which everything stops working.
Another stormy winter ahead?
Now it feels like history is repeating itself. I have felt misgivings since early October this year, because like that disastrous winter two years ago, we have had virtually no frosts in York (or indeed elsewhere) this year. I'm a gardener and a cyclist, so I notice when it's frosty, and while I'm no fan of icy roads, it does bother me when winter doesn't behave like winter.
On the railways, we also monitor leaf fall, because as this video explains, wet compacted leaves on the line are to train drivers what black ice is to motorists. So I can tell you with confidence that this year, the trees held onto their leaves until late November then lost them abruptly over about three weeks, on a curve that looked like none of the winters that had gone before...except 2013/14.
|Malham Cove becomes (briefly) UK's highest waterfall, Dec 2015|
|Malham Cove's waterfall bypasses the dry valley which |
usually emerges at the toe of the limestone cliff
You'd think that was bad enough, but I'm worried about the rest of the winter. Warm, wet and windy is bad news for most of us, but the reason it worries earthworks engineers like me is best illustrated by two graphs:
- The first graph by the British Geological Survey (BGS) shows the strong relationship between high rainfall events and subsequent landslides (and there's a similar pattern for sinkholes here).
- the second graph (unpublished) compares the quantity of rainfall per month on a particular section of the rail network with the delay minutes caused by earthworks and drainage. High rainfall can result in serious disruption, but not usually at the time: it tends to be January to April where the delay really racks up. The reason is simple: both flooding and earthworks failures are related to the level of saturation in the soil. The same amount of rainfall can cause massive disruption on ground which is already saturated, while on dry soil it sinks in and you would hardly notice it.