A new transatlantic academic research project will focus on strengthening global coastal sea defences.
Heriot-Watt University in Edinburgh, Scotland, and Virginia Tech in Blacksburg, Virginia, USA, are working on an adaptation approach for resilient coastal infrastructure against sea level rise, also known as the Pioneer project.
The research has been funded by the Engineering and Physical Sciences Research Council (EPSRC) early career researcher international collaboration grant. EPSRC is part of UK Research and Innovation, the national funding agency for investing in science and research.
The frequency and severity of coastal flooding events has been predicted to surge in the coming decades as climate change drives sea levels higher.
The research being conducted by the two universities will investigate how the soil behind sea walls is impacted by repeated wetting and drying cycles over time from waves overtopping the sea walls. The aim is to highlight areas where the design and resilience of sea walls could be strengthened.
Heriot-Watt’s School of Energy, Geoscience, Infrastructure and Society geotechnical engineering assistant professor Melis Sütman said: “The sea level around the UK has already risen by around 1.5mm a year on average from the start of the 20th century. And even in the best case climate change scenario, the sea level will continue to rise. So, our coastal defence structures will be of paramount importance to defend our shorelines – not only for the UK, but also for the United States on the other side of the Atlantic.”
Based on the Environment Agency’s research, Under a low emissions scenario, by the year 2300, the sea level for London and Cardiff is predicted to rise between 0.5m and 2.2m and up to 1.7m for Edinburgh and Belfast. Under a high emissions scenario, this increases to between 1.4m and 4.3m for London and Cardiff, and between 0.7m and 3.6m for Edinburgh and Belfast.
According to the National Ocean Service in the US, the coastal sea level by 2050 is predicted to be between 0.25-0.30m higher than in 2020.
“According to the Intergovernmental Panel on Climate Change, unavoidable sea level rise will bring cascading and compounding impacts resulting in flooding and damage to coastal infrastructure that cascades into risks to livelihoods, settlements, health, well-being, food and water security in the near to long-term,” Sütman said.
She added that the rising sea level also has strong economic consequences. For example, the investment needed to protect London is expected to exceed £20bn. And at Staten Island in New York City, US$165M is being invested to build an 8.5km seawall along the coastline to build resilience to sea level rise and extreme events.
The research will involve testing wave overtopping scenarios on interfaces that mimic the interaction between sea walls and the backfill soils. At Heriot-Watt, tests will take place in the lab on a thermo-hydro-mechanical direct shear interface device, which the university claims to have developed as a world-first. The device will allow numerous scenarios to be tested and measured. These include different water contents, overtopping frequencies and lengths, and properties of the both the soil behind the wall and the wall itself.
“It means that we can create a soil and structure interface – or a concrete interface – in the lab in the size of 60mm by 60mm, so very small,” Sütman explained. “And we can apply almost every possible temperature and water content change to this interface. Because this is a small-scale device, the setup is easier – and it’s cheaper – so we’ll be able to investigate many different parameters in a relatively short amount of time.”
Virginia Tech will then conduct its set of experiments on a full-sized wall that is 5m in height.
Virginia Tech Charles E Via Jr Department of Civil and Environmental Engineering’s geotechnical engineering associate professor Sherif Abdelaziz said: “Our large-scale tests will investigate how the soil and wall are affected by different levels of temperature, suction, water pressure and other parameters.
“Heriot-Watt will then perform additional lab-scale tests to investigate the conditions we record at full-scale. So, our investigations on each side of the Atlantic will very much go hand-in-hand.”
Pioneer’s advisory board features world-renowned experts from both academia and industry. These include former Institution of Civil Engineers president Paul Jowitt, University of Edinburgh environmental engineering chair and research institute head Lindsay Beevers, and Virginia Tech geotechnical engineering professor Thomas Brandon.
Also involved in the project is US infrastructure consulting firm Aecom. Its offices in both the UK and US will help to share the research results and apply them in practice. Also in the UK, William Allsop Consulting, which specialises in seawall design, will be consulted to advise on the practical implications of the research.