IAP-24-084
Impacts of rapid proglacial lake formation on glacial and proglacial systems in SE Iceland
Many temperate glaciers world-wide are retreating in response to climate change resulting in the formation and expansion of ice-contact proglacial lakes. These lakes can influence glacial dynamics by accelerating ice loss. Lake terminating glaciers can lose mass more effectively than land terminating ones via iceberg calving (Carrivick and Tweed, 2013; Dell et al., 2019). As lakes grow, mass loss and glacier margin retreat is enhanced, accelerating as lakes deepen (Carrivick and Tweed, 2013). They also lead to the decoupling of glaciers to the proglacial system, reducing sediment supply to the outwash plains and impacting the hydrodynamic behaviour of rivers (Carrivick and Tweed, 2013). Proglacial lakes and their expansion can also be a hazard and pose risk to infrastructure and life. Proglacial lakes can influence glacial dynamics, lead to the ‘decoupling’ of glaciers from their outwash plains and cause complex hazard cascades that pose risk to life and infrastructure. Despite their importance, there have been few detailed studies of proglacial lake formation and associated impacts.
The following research questions seek to address current gaps in our understanding of the systems:
1. To what extent do proglacial lakes impact glacial dynamics and enhance glacial recession rates?
2. How do proglacial lakes impact sediment dynamics and modulate downstream fluvial and coastal systems?
3. How do the formation, growth and dynamics of proglacial lakes impact hazard cascades and risk mitigation strategies?
Numerous lake-terminating, actively receding glaciers in SE Iceland provide a perfect natural laboratory to investigate the impact of climate on proglacial lake dynamics and consequent impacts on glacial and proglacial systems. The outlet glaciers of the Vatnajökull ice cap have recently developed proglacial and supraglacial lakes at glacier termini as a response to rapid thinning and retreat (e.g., Fjallsjökull, Hoffellsjökull, Kviarjökull and Skeiðarárjökull). Changes of the glacier margin positions, and lake extents are well documented (e.g. Thórarinsson, 1939; Schomacker, 2010, Evans et al. 2019; Guðmundsson et al., 2019); however, very little research has been conducted on the interactions between the glacial and lacustrine processes within these active proglacial lakes. These recently formed proglacial lakes provide the ideal natural laboratory for a process-based study with known lake and ice-marginal histories, together with the opportunity to link climatic, glaciological, lacustrine, fluvial and coastal processes.
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Image Captions
Oblique aerial view of the eastern Gígjukvísl proglacial lake at Skeiðarárjökull, May 2024 (Photo: Andy Russell).,Oblique aerial photo of the Gígjukvísl meltwater river exiting a proglacial lake with distant views of Skeiðarársandur, May, 2024 (Photo: Andy Russell).,Bathymetric survey of the eastern Gígjukvísl proglacial lake at Skeiðarárjökull, June 2022 (Photo: Andy Russell).,Oblique aerial view of the eastern Gígjukvísl proglacial lake at Skeiðarárjökull, May 2024 (Photo: Andy Russell).
Methodology
Geophysical surveys (swath bathymetry, acoustic sub-bottom profiling), drone surveys, and sediment cores collected on proglacial lakes will be used to: characterise lake bathymetry, map proglacial lake system geomorphology, calculate stored lake sediment volume, visualise the acoustic stratigraphy of lacustrine sediments and to investigate the factors influencing iceberg calving and glacier retreat through 3D model simulations. Thermistor and electrical conductivity strings will be used to characterise lake thermal regime and identify en- and subglacial meltwater inputs. Suspended sediment, turbidity measurements and repeat bathymetric surveys will allow determination of sediment flux. The student will gain skills in; processing, interpreting, and analysing geophysical, bathymetric, sedimentary, hydrological data and data synthesis. Experience will be gained in the use of key industry standard geophysical, geomorphological and geological software, as well as a state-of-the-art glacier modelling programme. The latter involves the Helsinki Discrete Element Model (HiDEM) (Åström et al., 2013), a brittle-elastic fracture model that has been used in investigations of iceberg calving across Greenland (Benn et al., 2023), Svalbard (Vallot et al., 2018) and Antarctica (Crawford et al., 2024). This will be the first application of the model in an Icelandic setting.
Field expeditions will involve two seasons in SE Iceland in 2026 and 2027. A geophysical survey (swath bathymetry, acoustic sub-bottom profiling) will be undertaken on selected proglacial lakes. These data will be used to map the geomorphology of the lake floor, calculate the sediment volume and to visualise the acoustic stratigraphy of the buried lake sediments. Sediment cores will be collected to ground truth the acoustic stratigraphy and allow laboratory-based lithofacies analysis. Lake temperature depth profiles will be determined using strings of thermistors to identify meltwater input, thermal regime and water column characteristics. All field data collection will inform a series of model simulations, conducted on an idealised domain, that will investigate the seasonal controls on iceberg calving as well as the evolution of calving regimes over 20 years of glacial retreat.
Project Timeline
Year 1
Research design and development of detailed project methodology. In-house training in geophysical data acquisition and processing will be provided. Introduction to modelling software and high-performance computing environment. Field season 1.
Year 2
Analysis of field data, refinement of fieldwork methodology, analysis and visualisation of geophysical data. Establishment of model domain and initiation of model simulations. Field season 2.
Year 3
Complete processing and analysis of field and remotely sensed data. Complete model simulations. Write draft publications; present at conference; draft thesis.
Year 3.5
Complete and submit thesis; finalise remaining publication manuscripts.
Training
& Skills
The student will receive training in relevant GIS and geophysical techniques and specialist software packages, including the Helsinki Discrete Element Model (HiDEM). The student will be introduced to high-performance computing environments, receiving training from the supervisory team as well as publicly accessible workshops provided by EPCC (Edinburgh) and the CSC-IT Centre for Science (Helsinki, Finland). Training in field data collection techniques, such as seismic refraction surveys and sediment coring will be provided. The student will partake in a RYHA Powerboat level II boat-handling course.
The student will be encouraged to write papers for publication throughout the duration of the project. The supervisory team will support the development in writing skills.
References & further reading
Åström, J. A., Riikilä, T. I., Tallinen, T., Zwinger, T., Benn, D., Moore, J. C., & Timonen, J. (2013). A particle based simulation model for glacier dynamics. The Cryosphere, 7(5), 1591–1602. https://doi.org/10.5194/tc-7-1591-2013
Benn, D. I., Todd, J., Luckman, A., Bevan, S., Chudley, T. R., Åström, J., Zwinger, T., Cook, S., & Christoffersen, P. (2023). Controls on calving at a large Greenland tidewater glacier: stress regime, self-organised criticality and the crevasse-depth calving law. Journal of Glaciology, 1–16. https://doi.org/10.1017/jog.2023.81
Carrivick, J.L., Tweed, F.S., 2013. Proglacial lakes: character, behaviour and geological importance. Quaternary Sci. Rev., 78, 34-52.
Crawford, A., Åström, J., Benn, D. I., Luckman, A., Gladstone, R., Zwinger, T., Robertsen, F., & Bevan, S. (2024). Calving Dynamics and the Potential Impact of Mélange Buttressing at the Western Calving Front of Thwaites Glacier, West Antarctica. Journal of Geophysical Research: Earth Surface, 129(10), e2024JF007737.
Dell, R., Carr, R., Phillips, E. & Russell, A.J. (2019) ‘Response of glacier flow and structure to proglacial lake development and climate at Fjallsjökull, south-east Iceland’, Journal of Glaciology, 65(250), pp. 321–336.
Evans, D.J.A., Ewertowski, M.W., Orton, C. 2019. The glacial landsystem of Hoffellsjokull, SE Iceland: contrasting geomorphological signatures of active temperate glacier recession driven by ice lobe and bed morphology. Geografiska Annaler, 101A, 249-276
Guðmundsson, S., Björnsson, H., Pálsson, F., Magnússon, E., Sæmundsson, Þ., Jóhannesson, T., 2019. Terminus lakes on the south side of Vatnajökull ice cap, SE-Iceland. Jökull, 69, 1-34
Schomacker, A. 2010. Expansion of ice-marginal lakes at the Vatnajökull ice cap, Iceland, from 1999 to 2009. Geomorphology, 119 (3-4), 232-236
Thórarinsson, S. 1939. The ice dammed lakes of Iceland with particular reference to their value as indicators of glacier oscillations. Geografiska Annaler, 21A, 216–242.
Vallot, D. et al. 2018. Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard. Cryosphere 12, 609–625.
