Evolution of glacial lakes in Southern Patagonia Icefield between 1986 and 2023

Daniela A. Carrión O.^1*Jorge Berkhoff²Thomas Loriaux³Ryan Wilson⁴Camilo Rada⁵Felipe Ugalde^6,7Claudio Bravo Lechuga⁸

• ¹Departamento de Geografía, Facultad de Arquitectura y Urbanismo, Universidad de Chile, Santiago, Chile
• ²Institut für Geographie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
• ³VRIIC, Vicerrectoría de Investigación, Innovación y Creación, Universidad de Santiago, Santiago, Chile
• ⁴University of Huddersfield, Huddersfield, West Yorkshire, United Kingdom
• ⁵University of Magallanes, Punta Arenas, Chile
• ⁶Geoestudios Ltda., Las Vertientes, Chile
• ⁷Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
• ⁸Centro de Estudios Científicos, Valdivia, Chile

This article presents satellite-based monitoring of glacial lakes located in the vicinity of the Southern Patagonian Icefield (SPI) between 1986 and 2023, with a focus on year-by-year changes between 2015 and 2023. Glacial lakes in this region are of importance as their growth represents an indirect response to climate change and has implications for local ecosystems, tourism, and recreation. The growth of glacial lakes also has implications regarding the potential generation of Glacial Lake Outburst Floods (GLOFs), and this study therefore enables a better understanding of the evolution of the GLOF hazard associated with the SPI. Using a total of 93 Landsat and Sentinel-2 satellite images, glacial lakes were mapped with the aid of the Normalized Difference Water Index (NDWI) and visual analysis and differentiated into three distinct types (moraine-dammed, bedrock-dammed, and ice-dammed). In addition, the volume of glacial lake water was estimated using an empirical area-volume scaling approach. Our results show that the number, area and volume of glacial lakes around the SPI have increased by 34%, 29% and 31%, respectively, between 1986 and 2023. The most recent inventory (2023) identified 313 lakes with a total area of 639.09 km 2 and a total volume of 34.84 km 3 . Of the lakes identified in 2023, moraine-dammed lakes accounted for the largest portion (165), followed by bedrock-dammed lakes (76) and ice-dammed lakes (72). A temporal analysis of the lakes by type revealed that (1) bedrock-dammed lakes exhibited the greatest stability, (2) moraine-dammed lakes showed the most significant growth in number and total area, with the number of lakes stagnating after 2016, and (3) ice-dammed lakes were the most dynamic and variable. Overall, our results highlight that 1 Carri ón et al.