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Ítem The 2020 glacial lake outburst flood process chain at Lake Salkantaycocha (Cordillera Vilcabamba, Peru)(Landslides, 2021-06-01) Vilca, Oscar; Mergili, Martin; Emmer, Adam; Frey, Holger; Huggel, ChristianGlacial 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 m3. 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 m3/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 m3) was much larger than the volume of released water (57,000 m3, 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.Ítem A new GLOF inventory for the Peruvian and Bolivian(EGU General Assembly, 2019-04) Adam Emmer; Simon Cook; Joanne L. Wood; Stephan Harrison; Ryan Wilson; Alejandro Diaz-Moreno; John M. Reynolds; Juan Torres LazaroAbordar la cuestión de si las inundaciones repentinas de los lagos glaciares (GLOF) están cambiando en frecuencia y magnitud en los tiempos modernos requiere un contexto histórico, pero adolece de inventarios GLOF incompletos, especialmente en regiones montañosas remotas. Aquí, explotamos imágenes satelitales y aéreas multitemporales de alta resolución combinadas con datos documentales para identificar eventos GLOF en las Cordilleras glaciares de Perú y Bolivia, utilizando un conjunto de características geomórficas de diagnóstico. Se caracterizan y analizan más de 150 GLOF, superando con creces el número de eventos informados anteriormente. Proporcionamos estadísticas sobre la ubicación, magnitud, momento y características de estos eventos. Además, describimos varios casos en detalle y documentamos una amplia gama de cadenas de procesos asociadas con GLOF.Ítem Modelling the impact of a GLOF scenario at Parón lake, Cordillera Blanca, Perú, using a novel multi-phase topographical and geological procedure(EGU General Assembly, 2021-04) Hilbert Villafane Gomez; Juan C. Torres Lázaro; Adriana Caballero Bedriñana; Harrinson W. Jara Infantes; Enver L. Melgarejo Romero; Julia E. Araujo Reyes; Christian Yarleque; Stephan Harrison; Ryan Wilson; Joanne L. Wood; Neil F. GlasserLa Cordillera Blanca está experimentando un rápido deshielo debido al calentamiento climático, especialmente desde finales del siglo XX. Este proceso ha resultado en la formación de nuevos lagos glaciares y un aumento en el volumen de los lagos existentes, algunos de los cuales representan un riesgo en forma de inundaciones por desbordamiento de lagos glaciares (GLOF); como el lago Parón en la Cordillera Blanca, que representa un peligro importante para la ciudad de Caraz y poblaciones menores ubicadas en la subcuenca Llullán-Parón. Aquí, modelamos un posible escenario de ruptura de presa y generación de GLOF en el lago Parón utilizando un procedimiento de modelado numérico novedoso que, entre otros factores, considera la estructura geológica de la presa natural. En general, este procedimiento incluye cuatro fases distintas: (1) estimación del impacto potencial de una avalancha de hielo en el lago Parón proveniente de los circos glaciares circundantes; (2) modelado de la posterior generación y propagación de ondas impulsivas; (3) análisis de los parámetros hidráulicos de una posible ruptura de la presa natural, considerando el material no erosionable dentro de estimaciones empíricas del hidrograma donde se interpreta la composición de la presa en base al mapeo geológico superficial y muestreo de sondeos realizados en la zona ; y (4) simulación de un GLOF potencial utilizando el modelo FLO-2D con datos de entrada de las fases anteriores. Los resultados del modelo indican que el lago Parón está en mayor riesgo por las avalanchas de hielo que se originan en el glaciar adyacente Hatunraju y que tales eventos tienen el potencial de generar ondas de impulso que podrían iniciar la erosión y una ruptura posterior de la presa natural. Considerando el peor de los escenarios de avalancha de hielo,3 / s. Este evento GLOF llegaría al área urbana de la ciudad de Caraz en alrededor de 36 a 42 minutos con tasas y alturas de inundación que fluctúan entre 11,2 m/s a 22,4 m/s y 9,9 m a 19,7 m, respectivamente.Ítem DInSAR monitoring of glacier dynamics in Cordillera Blanca and Vilcabamba(EGU General Assembly, 2021) Christian Riveros Lizana; Raul Espinoza Villar; Harrison Jara Infantes; Juan Carlos Torres Lazaro; Instituto Nacional de Investigación en Glaciares y Ecosistemas de MontañaThe effects of climate change are causing atypical changes dynamics of tropical glaciers. Conventional methods and optical images were ineffective in measuring these changes periodically due to the complexity of remote mountainous regions and cloud cover. In this research, a Differential Interferometric Synthetic Aperture Radar (DInSAR) analysis has gone performed with Sentinel-1 data from February 2019 to March 2020 in the Cordillera Blanca and Vilcabamba for Mapping displacement and subsidence. The measurements were compared with surface temperature and precipitation, providing zonal statistics to identify and assess regions associated with Glacial Lake Outburst Floods (GLOFs) hazards and enhanced understanding of the glacier dynamics in response to changing climatic conditions.Ítem Monitoring the Stability of a Moraine Dam by Differential Interferometry (DInSAR) to Prevent GLOFs Disasters from Arhuaycocha Lake(International Conference on Sustainable Infrastructure, 2021-12-07) Christian Riveros Lizana; Raul Espinoza Villar; Harrison Jara Infantes; Juan Carlos Torres Lazaro; Instituto Nacional de Investigación en Glaciares y Ecosistemas de MontañaThe Cordillera Blanca in Peru is the most heavily glaciated tropical mountain range in the world (Emmer et al., 2020), where 800–850 km2 total glacial area in 1930 decreased to 600 km2 at the end of the 20th century (Kaser, 1999). The decline has resulted in the formation of moraine-dammed lakes from flow stagnation and recession of glacier tongues (Harrison et al., 2018) affecting 230 glacial lakes in the region, of which 119 were moraine-dammed (Emmer & Vilímek, 2013). The fast growth and formation of lakes caused a dramatic increase in glacial lake outburst flood (GLOF) occurrence from 1930 to 1970. A previous decline (Emmer, 2017) is associated with the Little Ice Age, while GLOF incidence throughout the 21st century as lakes and glaciation respond more dynamically is associated with anthropogenic climate warming (Anacona et al., 2015). Although the GLOF frequency has not fluctuated directly in response to global climate, it will increase as the global climate continues to warm, with hazardous impacts for downstream regions (Harrison et al., 2018). Most of the recorded GLOFs from moraine-dammed lakes in the Cordillera Blanca were caused by slope movements into lakes in which the displaced material was dominated by icefalls, snow avalanches, and rockfall (Emmer & Cochachin, 2013) producing displacement waves, which may overtop, deforming or displacing a lake’s moraine dam (Jawaid, 2017). It is also clear that intense rainfall, the extreme variability of air temperature, or snowmelt will lead to a rise in the water level of the lake (Yamada & Sharma, 1993). This causes a deformation that can be identified through interstitial pressure measurements (Corsetti et al., 2018). DInSAR techniques have been developed to measure the temporal behavior of the displacements or deformation (Toural Dapoza et al., 2019). With ascending and descending DInSAR measurements it is possible to calculate 3D deformation of glaciers at one instance of time (Samsonov, 2019). It is necessary to have two independent acquisition modes from the ascending and descending line of sight (LOS) motions and solve the geometry relationship (incidence angle and satellite tracking heading angle) which are inverted to retrieve the horizontal and vertical components of the displacement. This developed methodology is detailed in Fig. 1 and we call it multi-geometry data LOS fusion The multi-geometry data fusion LOS methodology shows that the moraine dam of Arhuaycocha lake suffered subsidence of 17 cm (Fig. 2). The average subsidence zone was concentrated around the drainage channel (Fig. 2), and the zone of greatest subsidence was recorded at the lateral base. The dam shows higher displacement in the greatest rainfall seasons (Fig. 3). We concluded that subsidence in the moraine dam tracked with continued precipitation in wet months, and the loss of storage in dry summer months triggered rebound.