Interferometric Synthetic Aperture Radar
Urbanization has always led to urban sprawl in the United Kingdom since the Industrial Revolution, as evidenced by the fact that urban populations in the UK changed from 13.5% in 1670 to 43.5% in 1851, as well as the formation of urban clusters and conurbations in the Manchester and Birmingham area in this time: changes in transport infrastructure and market access had a large effect on urban growth beyond natural increase. 1 Therefore, urban development on brownfield sites as well as urban sprawling skyrocketed. This theoretically causes long-term subsidence threats, as the soil is loaded with weight by buildings and infrastructure created to meet the demand of the growing urban population. Furthermore, the expansion of asphalt and concrete usage in infrastructure during urban sprawl reduces the infiltration rate of soils covered by brownfield sites, which lowers the phreatic zone. This also creates cavities underground as groundwater is slowly drained through the hydrological cycle, inducing subsidence.
The economic impact of subsidence is clear: during my internship with GeoKinesia in the summer of 2025, I created my own chart (figure A to the right) for the annual subsidence-based insurance claims in the UK from 2005-2025, which related to property and infrastructure-based damage. 2 The reason for recent spikes in these statistics, such as the instance in 2018, is when there is prolonged hot, dry weather. This confirms that climate
change further exacerbates the risk of subsidence events, by further reducing groundwater infiltration. This means that the UK is more vulnerable to less predictable changes in our climate. This is due to the fact that urbanization and urban sprawl are a continuing trend in the United Kingdom, placing more pressure on construction areas, and posing a significant risk to existing urban infrastructure. Why is InSAR a less common monitoring method in urban Britain? A potential solution could be the expanded use of InSAR, which has already proven it to be a successful monitoring technology globally for large-scale projects, such as mining, railway and infrastructure management. InSAR is used for urban purposes globally, even though reports prove that most modern models are not precise enough to assess buildings on an individual level. This is universally concluded to be due to a combination of a more complicated scattering environment for Synthetic Aperture Radar, where buildings can cover certain details from satellite imagery, and material variance can make it 1 Alvarez-Palau, E. et al. (2020) ‘Transport and urban growth in the first industrial revolution’, available at: https://www.campop.geog.cam.ac.uk/research/occupations/outputs/preliminary/marketaccesspresteam.pdf. 2 Elliott-Grey, C. (no date) ‘Predicting and preparing for the increasing risk of subsidence’, Chartered Insurance Institute. Available at : https://www.cii.co.uk/news-insight/insight/articles/predicting-and-preparing-for- subsidence/82501488-a3e4-444d-b156-ce7e7c5c0d4d. See also Clark, L. (2025) ‘Insurance supports tops £150 million for homes affected by subsidence’, Association of British Insurers 11 th August. Available at: https://www.abi.org.uk/news/news-articles/2025/7/insurance-support-tops-150-million-for-homes-affected- by-subsidence/ . For subsidence caused by longwall mining, see Lannacone, J.-P. et al. (2014) ‘Characterization of Longwall Mining Induced Subsidence by Means of Automated Analysis of InSAR Time-Series’, available at: https://site.tre-altamira.com/wp-content/uploads/2014_- longwall_mining_induced_subsidence_automated_analysis_InSAR_Timeseries.pdf.
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