Geohazards and Climate Change: Compressibility

Lead Supervisor: Dr Marcus Dobbs

Location: British Geological Survey, Shallow Geohazards and Earth Observation: Engineering Geology

Duration: 6 weeks

Suitable undergraduate degrees: geology, geohazards, engineering geology, soil mechanics, remote sensing, data analytics.

Project background

One of BGS’s main objectives is to enhance sustainable development and the resilience of people, property, and places to shallow geohazards, through a better understanding of ground risk. A core research activity is characterising the properties of key geological units and their susceptibility to geohazard processes. Over the past few decades BGS has development specific datasets and reports to inform decision-makers  within the planning and development, civil engineering and finance sectors (e.g. GeoSure, BGS Civils, BGS Formation Studies Reports). More recently, BGS has also begun to explore how the susceptibility of weather-driven shallow geohazards could change under different climate scenarios to help inform the development of climate change adaptation and mitigation measures (e.g. Geoclimate: shrink-swell).

It has been shown in that the area along the river Thames extending into central London is compressing by approximately 3mm/yr. (Aldiss et al, 2014). Compressible ground is an important hazard in coastal lowland areas (such as London), which tend to be highly populated and will experience the largest impact of sea level rise but are also the most geologically susceptible to subsidence. With climate change forecasts indicating an increase in the frequency and intensity of winter storms and other adverse weather events these more susceptible, lower lying, coastal areas are more at risk of coastal flooding and inundation. Along with causing damage to buildings the compression of the ground can cause significant damage to roads and utilities typically buried beneath the road.

The objective of this project is to develop a better understanding of the physical properties of compressible deposits (such as peat, head, alluvium and artificial deposits) and how the susceptibility of these deposits to compression (particularly consolidation) may alter with climate change.

The project will involve:

• evaluating the methodology used to create the current BGS GeoSure Compressible Ground dataset against any recent published literature for similar national- and regional-scale datasets;
• review of literature on the effect of climate change on compressible deposit susceptibility;
• using the BGS National Geotechnical Properties Database to produce geotechnical parameter summaries (index properties, coefficient of consolidation, compression index, etc) of key geological units in the UK that are susceptible to compression, including identification of data gaps;
• using available InSAR data (from the European Ground Motion Service) to determine rates of compression (subsidence) at a range of locations representing geological units with different levels of susceptibility to compression: this will include evaluating the effects of historic extreme weather events on rates of subsidence;
• summarising findings in a brief report, to include: any identified data and knowledge gaps; recommendations for future research; and recommendations for improving existing, and developing future, compressibility datasets in BGS.

Following the initial literature review, and evaluation of data from the National Geotechnical Properties Database and InSAR, the student will use their findings to determine how to progress their study of the potential effects of climate change on compressibility. This could include:

• further literature review;
• fieldwork to obtain sample material and/or install in situ monitoring sensors at locations representing one or more key geological units types;
• laboratory based-analysis of samples to determine geotechnical properties (index properties, coefficient of consolidation, compression index) to address existing data gaps;
• devising a novel laboratory-based experiment to simulate the effects of different climate change scenarios on compressibility.

Don Aldiss, Helen Burke, Barrie Chacksfield, Richard Bingley, Norman Teferle, Simon Williams, David Blackman, Richard Burren, Nigel Press. 2014. Geological interpretation of current subsidence and uplift in the London area, UK, as shown by high precision satellite-based surveying. Proceedings of the Geologists’ Association, Volume 125, Issue 1, Pages 1-13. https://doi.org/10.1016/j.pgeola.2013.07.003.