From Heat to Hazard: How Climate Extremes Affect Coastal Rock Slope Stability

Project Summary

The southwest coast of Dorset is one of the most landslide-active regions in the UK, where coastal cliffs are shaped by wave erosion, rainfall, and increasingly, temperature extremes. During heatwaves, the British Geological Survey (BGS) issues public warnings about elevated rockfall risk—often coinciding with peak visitor numbers. This convergence of environmental hazard and human exposure raises urgent questions about public safety and risk communication.

The frequency and intensity of UK heatwaves have increased significantly (e.g. 84 since 2000 vs. 44 from 1960–2000), prompting concern about their role in cliff deterioration. This project investigates how thermal processes contribute to rockfall events. Using UAV-based infrared thermography, UAV-LiDAR, and in-situ sensors, the project will monitor temperature-driven changes in cliff stability. While Dorset is the primary study area, the approach could be extended to other UK coastal sites. Findings will inform hazard forecasting and support improved public safety strategies for communities and infrastructure exposed to rock slopes.

Uncovering Climate-Driven Rockfall Mechanisms

Understanding how heatwaves influence rockfall is a growing scientific priority, especially as climate extremes become more frequent. While seismic activity, rainfall, and freeze–thaw cycles are well-established triggers, recent studies suggest that thermal stress caused by surface heating and cooling may also affect slope stability. Temperature fluctuations can lead to expansion and contraction of rock surfaces, driving fracture propagation, subcritical crack growth, and eventual detachment. These mechanisms have been observed in granitic exfoliation sheets in Yosemite National Park (Guerin et al. 2021), for example, but has yet to be fully understood for a diverse range of rockmass types including those along UK coasts.

Project Approach

This project will deploy state-of-the-art remote sensing technologies, including UAV LiDAR and UAV-based infrared thermography, to characterise and monitor coastal cliff sites with diverse geological profiles. Study locations may include West Bay (Dorset), Staithes (North Yorkshire), and selected sites in Scotland. The experimental design will combine high-temporal-resolution monitoring during heatwaves and other target periods, with longer-term baseline monitoring to capture seasonal and diurnal thermal behaviour. UAV thermography will be used to map surface temperature distributions, revealing zones of seepage, intact vs. fractured rock, and areas of thermal anomaly. Repeat UAV LiDAR surveys will quantify cliff deformation and detect rockfall events. This dual-scale approach will allow the project to distinguish between short-term thermal stress responses and longer-term deterioration trends.

There is also potential to install slope instrumentation as part of the 5G Rural Dorset Project, enabling continuous, long-term monitoring of cliff temperature and behaviour. This would complement the UAV-based campaigns by providing high-frequency time-series data, especially during periods of thermal stress. This integration of remote and in-situ monitoring would allow the project to explore both short-term responses to heatwaves and long-term deterioration trends, offering a more complete picture of climate-driven instability.

The PhD will involve:

The successful candidate will be encouraged to shape their own research questions within the overarching theme of heatwave-driven cliff deterioration. The project will be structured around several key phases:

• Site characterisation: Geological and thermal profiling of selected coastal cliffs using UAV LiDAR and infrared thermography, supported by BGS expertise.
• Monitoring: Development of a dual-scale monitoring strategy, combining long-term baseline observations with high-temporal-resolution campaigns during heatwaves and other thermal stress events.
• Data analysis and modelling: Processing UAV and in-situ sensor data to identify patterns of thermal expansion, fracture propagation, and rockfall occurrence. This may include thermal modelling and stress analysis using numerical methods.
• Risk assessment and communication: Evaluating public exposure and risk, including behavioural aspects and hazard communication strategies for coastal visitors and infrastructure managers.

Throughout the PhD, the student will gain hands-on experience with remote sensing technologies, geomechanical analysis, and environmental risk modelling. Training and collaboration opportunities will be available through the School of Earth and Environment and the British Geological Survey.

Candidate Profile

The ideal candidate will have a background in geosciences or a closely related discipline such as engineering geology, physical geography, or environmental geoscience. Experience or interest in remote sensing, geomechanics, or climate-related hazard assessment would be advantageous. Familiarity with programming tools (e.g. Python) for data analysis and modelling is desirable. The student will be based in the School of Earth and Environment at the University of Leeds, with access to a vibrant research community, interdisciplinary seminars, and technical training. Collaboration with the British Geological Survey and the 5G Rural Dorset Project will offer additional opportunities for fieldwork, data access, and professional development.