Glacial lakes at the Juncal catchment, Chilean Central Andes: origin, evolution and GLOF hazard management challenges

The Juncal catchment, located in the Valparaíso Region, Central Andes of Chile, hosts 79 glaciers, including Monos de Agua and Juncal Norte glaciers. The latter has an active glaciological monitoring at least since 2020, which has allowed an accurate assessment of its recent evolution. On a regular basis, research at this site has focused on the hydrological significance both to the Region and for the Aconcagua River. Nonetheless, glacier hazards have received less attention, posing an opportunity for new studies.

In this contribution, we present the chronological evolution of three glacial lakes that originated in the Juncal catchment: (1) Juncal Norte Glacier (DGA code CL105400072A) proglacial lake, at 2,940 m a.s.l.; (2) proglacial lake 077, located in front of the CL105400077 Glacier at 3,560 m a.s.l., and (3) glacial lake 088, associated with the rock glacier CL105400088, at 4,055 m a.s.l., which is currently drained.

Through the analysis of Sentinel-2 and PlanetScope imagery, we determined that these lakes formed at the end of the 2018 boreal summer, whilst their expansion is still ongoing. By the end of 2025 summer, the extension of Juncal Norte and 077 glacial lakes reached 4 and 2 ha, respectively, whereas the 088 lake would have reached a maximum extension of 2.1 ha by May 2023. Our results show that the 088 glacial lake drainage began at the start of the summer of 2024, ending by February 2024. Special attention is given to the 077 glacial lake’s expansion, which is confined by the glacier’s frontal moraine, and is located 800 m above the river drained from the Juncal Norte Glacier. Such a condition is critical in the scenario of a GLOF, due to the high potential energy involved in an eventual outburst.

The morphological heterogeneity of these glacial lakes, combined with their location and the particular characteristics of the glaciers that originate them, poses important challenges for field surveys and the precise evaluation of the GLOF hazard assessment within the Juncal catchment.