Abstract
The diachronic analysis of aerial and satellite imagery, uncrewed aerial vehicle (UAV) andin situsurveys obtained between 1956 and 2019 are employed to analyse landform surface kinematics for the Tapado site located in the Dry Andes of Chile. A feature tracking procedure was used between series of orthorectified and co-registered images to calculate surface velocities on several ice-debris landforms, including rock glaciers and debris-covered glaciers. For the active rock glaciers, the results exhibit typical viscous flow, though local destabilisation process seems to occur, increased velocities since 2000 (>1 m/yr) and terminus advance. Nevertheless, the debris-covered glaciers displays heterogeneous spatial patterns of surface velocities, together with collapse (downwasting) associated with the development of thermokarst depressions and supraglacial ponds. Our findings show that surface kinematics and multitemporal observations derived from different sensors are valuable tools for differentiating between glacial and periglacial features. The pluri-decadal time series since 1956 constitute a unique dataset for documenting the surface kinematics of creeping mountain permafrost in the Southern Hemisphere. The approach developed in this work offers a way forward to reconstruct the recent behaviour of glacial and periglacial features in the Andes, where archival aerial photographs are available but have not previously been processed rigorously to obtain an accurate assessment of landform kinematics.
Highlights
Cryosphere components in high-mountain regions such as glaciers, snow cover and permafrost are sensitive to environmental changes such as rising temperatures because of their proximity to melting or thawing conditions (Haeberli and Beniston, 1998; Barry and Gan, 2011; Hock et al, 2019)
In the Dry Andes (17°30 ́–35°S, sensu Lliboutry, 1998), rock glaciers are regarded as the unequivocal expression of the creep of mountain permafrost, and it is assumed that they play an essential role as water reservoirs due to their prevalent occurrence in the high Andean landscape (Corte, 1976; Schrott, 1996; Azócar and Brenning, 2010; Perucca and Esper Angillieri, 2011; Schaffer et al, 2019)
We provide a systematic description of the development of rock glacier kinematics over distinct types of landforms since 1956
Summary
Cryosphere components in high-mountain regions such as glaciers, snow cover and permafrost are sensitive to environmental changes such as rising temperatures because of their proximity to melting or thawing conditions (Haeberli and Beniston, 1998; Barry and Gan, 2011; Hock et al, 2019). In the Dry Andes (17°30 ́–35°S, sensu Lliboutry, 1998), rock glaciers are regarded as the unequivocal expression of the creep of mountain permafrost, and it is assumed that they play an essential role as water reservoirs due to their prevalent occurrence in the high Andean landscape (Corte, 1976; Schrott, 1996; Azócar and Brenning, 2010; Perucca and Esper Angillieri, 2011; Schaffer et al, 2019). In this mountain region, rock glaciers, push moraines and debris-covered glaciers assemblages represent cases of intricate permafrost-glacier interactions (Trombotto et al, 1997; Bodin et al, 2010). Environmental laws designed to protect surface and subsurface perennial ice reservoirs (sensu stricto glaciers and rock glaciers) have been implemented in Argentina, and are currently in discussion in Chile, which means that their correct characterisation and monitoring have become a highly relevant environmental matter (Brenning, 2008; Brenning and Azócar, 2010; Kronenberg, 2013; Wainstein et al, 2020)
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