Climate warming is causing dramatic changes to Earth’s mountain environments, which are becoming more developed as populations and economies expand. At high, cold altitudes, mountainsides are in a frozen (‘permafrost’) state and are relatively stable. However, frozen mountainsides are thawing, and becoming unstable. Thawing is hypothesised to produce an increase in the number and size of rockfalls and large rock avalanches. This is important because: (i) increased rockfall and avalanche acitivity are a hazard to communities and infrastructure directly beneath permafrost rock slopes, and (ii) debris supplied from these mountainsides lands on glacier surfaces in valleys below and alters their behaviour, which affects meltwater resource. We are unable to accurately predict the physical response of thawing rock slopes to climate warming and adequately prepare for its impacts because of a lack of detailed field survey data and analysis on the state and dynamism of these faces.
This PhD project will use cutting-edge surveying technology to benchmark the thermal state and erosional flux of candidate rock faces in North America and/or the European Alps. The student will test the hypothesis that permafrost degradation can increase rockfall frequencies and volume by over an order of magnitude relative to a thawed, unfrozen thermal regime. The student will additionally quantify and explore the spatiotemporal distribution of rockfall activity across these large rock faces and explore these patterns in the context of thermal state more broadly and other geotechnical and climatological factors. Proposed methods include terrestrial ‘gigapixel’ photogrammetry for deriving 3D models of rock faces in unprecedented detail, 4D change detection to derive detailed rockfall event histories and enable analysis of spatiotemporal patterns of erosion and material redistribution, and ground-based thermal imaging to quantify rock surface temperature evolution. This information will be used as input to rockfall trajectory reconstruction and a model-based analysis of explanatory factors for driving erosion, including transient temperature evolution, frost-cracking intensity, and liquid water availability. Full training will be provided in all aspects of data collection, processing, analysis and modelling.
Key Research Gaps and Questions:
Can rockfall event histories provide insights into the thermal zonation of large, frozen mountainsides?
What are the key factors controlling debris release across these rock faces, and how might this debris supply change as slopes transition from ‘stable’ to ‘unstable’ regimes?
The project is suitable for a student with a background in geosciences or associated physical sciences, including computer science. Proficiency in Matlab or a similar programming language, and experience of undertaking research in remote regions is desirable, but not essential. For more information, please contact Dr Matt Westoby ([email protected]).
These are (3.5 year) fully funded PhD studentship awards available for entry September 2019. Each award includes fees (Home/EU), an annual living allowance (£14,777) and a Research Training Support Grant (for travel, consumables, as required).