The first country-wide map of relative land motion has been created by a team at the University of Nottingham. The team used hundreds of satellite radar images and worked with Geomatic Ventures Limited (GVL) – an innovative University spin-out company, to create a complete map of mainland Scotland.
The map covers a two-year period from 2015 to 2017 and was created using Intermittent Small Baseline (ISBAS) analysis, a novel satellite remote sensing technique. It showed a small but significant rate of land motion is occurring across almost the whole landscape. Rural areas are marked by subsidence over peatlands and landslides on steep slopes. The urban and industrialized areas of the Scottish Midlands clearly show the effects of historical coal mining and civil engineering.
The map was created to illustrate the problems facing governments when regulating onshore oil and gas production and storage in a modern landscape, influenced by industrial and land management practices. For instance, there is a perceived threat of subsidence and a potential risk of earth tremors related to fracking. Although these maps have been recently banned in Scotland, they can help to screen locations to inform government regulators whether fracking can be reasonably monitored and deployed safely in other parts of the UK and around the world.
In addition, they can help the oil and gas industry engage with local communities to show that good practice is in place and their activities are having little effect on the environment. Alternatively, regular monitoring using satellite techniques to track the vertical motion of the ground can be used to monitor the health of peatlands and detect landslides.
Dr. Stephen Grebby, Assistant Professor in Earth Observation and lead university investigator on the project.
“Tracking ground motion is also important for a wide range of other applications such as monitoring infrastructure and this is not just limited to Scotland," said Dr. Stephen Grebby, assistant professor in Earth Observation and lead university investigator on the project. "For example, our wide-area monitoring technique could be used to help identify and monitor ground instability issues along the whole stretch of the proposed HS2 route. This would provide information that could ultimately influence the plans for the final route for Phase 2 of HS2, or at least highlight existing ground instability issues that may need to be addressed during construction of the network.”
Maps like this could be seen as an important national asset to support risk assessment and mitigation, and consequently the design of future policies, the assessment of policy decisions and decision-making across a number of government departments.
This wide-area monitoring technique offers the future means of generating a European-wide relative land motion map. This would help identify ground instabilities in urban and rural areas alike, with greater coverage than previously possible.
The current study showed that large areas of Scotland’s vast lowland and highland peatland areas are dominated by subsidence. This is notable as collapsing peatlands are a significant source of greenhouse gases. According to the Scottish Natural Heritage, the carbon stored in Scotland’s solids is equivalent over 180 years of greenhouse gas emissions from Scotland at current emission rates.
“If Scotland is to reach its climate change targets, which are currently under scrutiny by the UK Committee on Climate Change, land motion maps like this can provide vital evidence on the health of peatlands and with regular monitoring, the beneficial effect of peatland restoration towards improving the carbon balance," said Dr. Andy Sowter, chief technology officer of GVL.