@article{Vilca2021,

title = {The 2020 glacial lake outburst flood process chain at Lake Salkantaycocha (Cordillera Vilcabamba, Peru)},

author = {Oscar Vilca and Martin Mergili and Adam Emmer and Holger Frey and Christian Huggel},

url = {https://link.springer.com/10.1007/s10346-021-01670-0},

doi = {10.1007/s10346-021-01670-0},

issn = {1612-510X},

year  = {2021},

date = {2021-06-01},

journal = {Landslides},

volume = {18},

number = {6},

pages = {2211--2223},

abstract = {Glacial lakes represent a threat for the populations of the Andes and numerous disastrous glacial lake outburst floods (GLOFs) occurred as a result of sudden dam failures or dam overtoppings triggered by landslides such as rock/ice avalanches into the lake. This paper investigates a landslide-triggered GLOF process chain that occurred on February 23, 2020, in the Cordillera Vilcabamba in the Peruvian Andes. An initial slide at the SW slope of Nevado Salkantay evolved into a rock/ice avalanche. The frontal part of this avalanche impacted the moraine-dammed Lake Salkantaycocha, triggering a displacement wave which overtopped and surficially eroded the dam. Dam overtopping resulted in a far-reaching GLOF causing fatalities and people missing in the valley downstream. We analyze the situations before and after the event as well as the dynamics of the upper portion of the GLOF process chain, based on field investigations, remotely sensed data, meteorological data and a computer simulation with a two-phase flow model. Comparison of pre-and post-event field photographs helped us to estimate the initial landslide volume of 1-2 million m 3. Meteorological data suggest rainfall and/or melting/thawing processes as possible causes of the landslide. The simulation reveals that the landslide into the lake created a displacement wave of 27 m height. The GLOF peak discharge at the dam reached almost 10,000 m 3 /s. However, due to the high freeboard, less than 10% of the lake volume drained, and the lake level increased by 10-15 m, since the volume of landslide material deposited in the lake (roughly 1.3 million m 3) was much larger than the volume of released water (57,000 m 3 , according to the simulation). The model results show a good fit with the observations, including the travel time to the uppermost village. The findings of this study serve as a contribution to the understanding of landslide-triggered GLOFs in changing high-mountain regions. Keywords GLOF. High-mountain areas. Impact wave. Moraine-dammed lake. Process chain. Rock avalanche Introduction Continued retreat of glaciers often leads to the formation of glacial lakes, retained behind stable rock dams (i.e. occupying glacier overdeepenings) or dammed by potentially unstable moraine dams. Such lakes can drain suddenly, releasing large amounts of water that can result in complex and potentially catastrophic downstream process chains. Glacial lake outburst floods (GLOFs) have been the subject of numerous studies covering many mountain regions around the world (Hewitt 1982; Haeberli 1983; Rich-ardson and Reynolds},

keywords = {GLOF, High-mountain areas, Impact wave, Moraine-dammed lake, process chain, rock avalanche},

pubstate = {published},

tppubtype = {article}

}