For the UK, 2023 was the second warmest year on record, and the warmest for Wales and Northern Ireland, with 2020, 2022 and 2023 in the top 5 warmest since being recorded in 1884; the top 10 warmest years have all occurred since 2003. In 2022, a temperature above 40oC was recorded for the first time in the UK, whilst a provisional January record high temperature of 19.6 was recorded in Kinlochewe in the Scottish Highlands on January 28.
With higher temperatures comes the ability to hold more moisture in the atmosphere, with 2023 one of the 10 wettest years since 1836. Indeed, the UK Met Office has named ten storms since 1 September 2023, with three alone being named in January 2024 (Henk, Isha and Jocelyn). This is the fastest sequence since storms started being named in 2015.
The Adaptation sub-committee of the UK Climate Change Committee projects that flooding is likely to be more frequent and severe affecting many infrastructure types, extended periods of rainfall will increase the likelihood of slope embankment failure with 8% of the UK’s transport network at medium or high risk of landslide disruption, whilst future high temperatures could cause rail lines to buckle, signal equipment overheat and fail and for road pavements to soften and rut.
The most recent independent assessment of the Adaption Committee found that the UK is unprepared for even the best-case scenario of climate change, and certainly not the current projections. They also reported that “the gap between the level of risk we face and the level of adaptation underway has widened”.
The risks from extreme weather are clear; in 2020 a train crash in Stonehaven was caused by a train hitting a landslide in heavy rain claiming the lives of 3 people and leading to Network Rail being fined £6.7 million for operational and maintenance failures. During flooding from Storm Desmond in 2015, the transport infrastructure of Cumbria was severely affected, with 107 road closures as a result of issues including flooding, landslips, subsidence and bridge damage. Of the estimated 354.8km of carriageway to have been damaged, over half (56.0%, 198.8km) was considered to be significant. Some of these led to significant diversions, the longest being around 70 miles.
The UK Government reports that the floods of 2015/16 cost the economy £16 billion, with economic losses from flooding between November 2019 and March 2020 estimated at £333 million, although without flood defences installed in recent years, the cost could have been around £2.4 billion.
Work is being undertaken, with a £2.6 billion, six-year project having protected over 300,000 properties from flooding in England, however, more needs to be done to assess transport routes to extreme weather and increase the resilience of critical transport routes. This could require a mix of hard, soft and hybrid solutions.
Typically, ‘hard’ solutions involve physical civil engineering interventions to achieve the desired impact; examples might include increasing drainage capacity through larger culverts or concrete river flood defences. Soft engineering solutions seek to use the natural environment and natural materials to be effective, with examples such as green drainage solutions to more slowly attenuate rainfall, or the use of targeted planting for slope stabilisation. Hybrid solutions, as the name suggests, are a mix of hard and natural solutions. A good example of these are the rain gardens in and around Cardiff City centre.
As Cardiff is the city with the highest risk of flooding in the UK, one measure taken to reduce the risk has been the creation of rain gardens around the city which reduces the risk of flash flooding from rainwater or from inundating the sewer system, instead slowing and cleaning the water before discharging it into the river. Installing retrofit SUDS such as this is more challenging than conventional SUDS, with significant engineering beneath the surface.
When looking to increase the resilience of infrastructure to extreme weather, systems such as this, and nature-based solutions in general are gaining more attention, with consideration being given, not just to the expected resilience benefits, but to the co-benefits such as increased biodiversity and reduced embodied carbon. In Cardiff, the rain gardens and uncovering of the dock feeder canal have been installed as part of wider schemes such as active travel networks and urban realm improvements.
Making the case for resilience and trying new methods and approaches vs traditional, pragmatic approaches is a challenge for many road owners and operators.
Maple Consulting is a partner working on the ICARUS project, which seeks provide a better understand of how to build a business case for resilience, balancing the services levels required with the costs and benefits of the solution. The project, led by Deltares (Netherlands), with partners Tecnalia (Spain), Ramboll (Denmark) and RDS (Ireland) has been funded by the Conference of European Road Directors, with funding provided by Denmark, Ireland, Netherlands, Norway, Sweden, Switzerland and the UK.
The project is nearing completion and has a variety of resources available already including baselines for climate change resilience assessments, a report on impact chains as a result of climate events, guidelines on minimum service levels and information on performance metrics to use when making the case for adaptation. Reports on evaluation of adaptation measures and on types of nature based solutions will be available in Spring this year.
More information is available on the project website, with deliverables and other resources available here >
