IAP2-23-120

Implications of climate change for geomorphological process and hazard cascades in glaciated catchments of central Patagonia

Glaciers in mountainous regions such as the Patagonian Andes are currently experiencing accelerated rates of recession in response to a rapidly changing climate. Transition from ‘glacial’ to ‘paraglacial’ conditions is typically characterised by destabilisation of mountainsides, liberation of large volumes of sediment, changes in proglacial meltwater routing, the development/expansion of proglacial lakes and changes in sediment flux to proglacial rivers systems. Newly developed process chains have the potential to generate hazards in the form of landslides, catastrophic mass flows (aluviones) and rapid changes to the fluvial and groundwater system as well as riparian vegetation. The Aysén region of Chile has recently experienced slope instability generated by glacier recession and intense rainfall events generating recent aluviones and floods which have resulted in loss of life and infrastructure.

Models of paraglaciation based on reconstructions of palaeo landforms and deposits do not necessarily allow the identification of complex and transient process cascades. Focussed studies of contemporary deglaciation and paraglacial processes can be used to generate models which can be used both to identify and mitigate the impacts of resulting hazards.

This project aims to (1) Test existing models of paraglacial process chains and (2) Develop new models for paraglacial response to deglaciation.

This study will focus on two locations in Aysén which contain a number of hazards and associated risk to local communities: (1) the Rio Mosco at Villa O’Higgins, which flanks the northern sector of the Southern Patagonian Icefield, and (2) the Exploradores valley, which flanks the northern border of the Northern Patagonian Icefield. The Rio Mosco drains a rapidly deglaciating environment catchment, subject to large scale hillslope failures and associated enhanced sediment supply to the fluvial system. The Exploradores valley has recently experienced rapid changes in the proglacial landscape as well as a range of hazards associated with deglaciation including, rock slope failures, aluviones, and glacial lake outburst floods.

Project objectives:
(1) Quantification of rates of ice-marginal and proglacial landscape change.
(2) Measurement water and sediment flux from the river catchments.
(3) Meteorological measurements including precipitation and temperature.
(4) Groundwater levels and fluxes.

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Image Captions

Location of the research area within Patagonia,Deglaciating mountainside in the Exploradores valley (Photo: Andy Russell),Rio Mosco catchment, Villa O’Higgins (Photo: Andy Russell)

Methodology

Fieldwork is required to fulfil the project aims and objectives including: maintenance of existing monitoring equipment, installation of new sensors, UAS (Uncrewed Aircraft System) surveys, ground surveys using dGPS and Ground Penetrating Radar (GPR). Field data will be used as a basis for hydraulic modelling and modelling fluvial sediment flux. This project capitalises on recent research projects: (1) in the Rio Mosco (2020-22) monitoring water level and channel conditions using sensors and cameras; and (2) dendrochronological reconstructions of flood magnitude and frequency in the Exploradores valley. Access to secondary data sets (meteorological, hydrological and UAS survey) will be provided via project collaborators to provide input to groundwater, hydraulic and sediment modelling. Satellite imagery will be used to map large-scale geomorphological change.

Project Timeline

Year 1

Research design and development of detailed project methodology. Training in UAS surveys, ground-based surveys, hydraulic and sediment transport modelling, use of GPR, deployment of monitoring equipment, Planning and completion of first field season.

Year 2

Analysis of field data, refinement of fieldwork methodology, analysis and visualisation of second field season.

Year 3

Complete processing and analysis of data. Present at an international conference and feedback to stakeholders in the Aysén region.

Year 3.5

Integration of results and finalising thesis writing.

Training
& Skills

Remote sensing, GIS, Surveying (dGPS, TLS), geomorphological/geological mapping, dendrochronology, surface/ground water monitoring, debris flow and hydraulic modelling, sedimentology.

References & further reading

Ballantyne, C.K., 2002a. Paraglacial geomorphology. Quaternary Sci. Revs. 21, 1935–2017.

Bañales-Seguel, C.; Salazar, A. & Mao. L. 2020. Hydro-morphological characteristics and recent changes of a nearly pristine river system in Chilean Patagonia: The Exploradores river network. Journal of South American Earth Sciences, 98, https://doi.org/10.1016/j.jsames.2019.102444

Cody, E., Anderson, B.M., McColl, S.T., Fuller, I.C.,Purdie, H.L. 2020. Paraglacial adjustment of sediment slopes during and immediately after glacial debuttressing. Geomorphology, 371, 107411.

Irarrazaval I., Dussaillant A., Vivero S., Iribarren-Anacona P. and Mariethoz G., 2022. Ice Dynamics and Morphological Changes During Proglacial Lake Development at Exploradores Glacier, Patagonia. Front. Earth Sci. 10:791487. doi:10.3389/feart.2022.791487

Mancini, D. Lane, S.N. 2020. Changes in sediment connectivity following glacial debuttressing in an Alpine valley system, Geomorphology, 352, 106987.

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