Anna Harrison (United Kingdom) 1; David Entwisle (United Kingdom) 1; Hughes Andrew (United Kingdom) 1; Andrew Hulbert (United Kingdom) 1; Lee Jones (United Kingdom) 1; Majdi Mansour (United Kingdom) 1; Lei Wang (United Kingdom) 1; Jim White (United Kingdom) 1; Chris Williams (United Kingdom) 1; Kathryn Lee (United Kingdom) 1
1 - British Geological Survey
Building damage caused by ground movement, a consequence of low rainfall and clay shrinkage, is often referred to as subsidence. Subsidence is estimated to cost the UK economy £3 billion over the past decade. The British Geological Survey (BGS) have developed GeoClimate – a decision support tool identifying subsidence susceptibility based on geology, groundwater processes and climate projections extending to 2080.
Clay shrink-swell is driven by the presence of active clay minerals including smectite and illite, which expand and contract due to water content change, and is directly linked to rainfall and temperature. The most susceptible geological units in the UK are predominantly in the south-east, encompassing London, plus adjacent areas highlighted for development. Based on future climate projections, it is likely that the UK, specifically the south-east, will experience warmer, drier summers, accompanied by wetter, warmer winters. This will exacerbate subsidence in susceptible areas, potentially affecting additional areas where subsidence reports are currently low.
Knowledge of potential future clay shrink-swell is important to stakeholders including infrastructure owners, developers, town planners, home owners and insurance providers, and likely to affect land-use and foundation design. These form the GeoClimate target user community. To ensure information is effectively provided it is vital that: the user community’s needs are identified: and that the data is scientifically robust, reliable and directly applicable. As such, the product has been driven by a stakeholder consultation process, which included workshops, data testing and feedback from government, commercial and academic end-users. This has influenced all aspects of the product, from scale and classification, to formatting and accessibility.
The decision support tool highlights the spatial variability of areas likely to be affected by increased subsidence. This is achieved through consideration of geological susceptibility, groundwater processes, and projected climate change. The geological control is provided by BGS’s 1:50 k scale mapped data. The potential groundwater processes are constrained by a groundwater distributed recharge model to provide soil moisture projections. The climate information used is based on the 2009 UK Climate Projections (UKCP09). These constituent parts of GeoClimate are robust, and the methodology calibrated, resulting in a state-of-the-art decision support tool that is built on a reliable and clear foundation.
GeoClimate provides information so that the impacts of clay shrinkage due to climate change and be mitigated. The cost and disruption of such prevention can be low, often many times lower than the repair bill following ground movement.