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Research paper thumbnail of Reducing risks from hazardous glacier lakes in the Cordillera Blanca (Peru): Six decades of experience and perspectives for the future

Research paper thumbnail of Modeling a glacial lake outburst flood process chain: the case of Lake Palcacocha and Huaraz, Peru

Hydrology and Earth System Sciences, 2016

One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk o... more One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of glacial lake outburst floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on 13 December 1941, killing about 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and preliminary hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5 to 3 × 10 6 m 3 were simulated, and two scenarios of 15 and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming moraine. Despite very high discharge rates (up to 63.4 × 10 3 m 3 s −1), the erosion from the overtopping wave did not result in failure of the damming moraine when simulated with a hydromorphodynamic model using excessively conservative soil characteristics that provide very little erosion resistance. With the current lake level, all three avalanche events result in inundation in Huaraz due to wave overtopping, and the resulting preliminary hazard map shows a total affected area of 2.01 km 2 , most of which is in the high hazard category. Lowering the lake has the potential to reduce the affected area by up to 35 %, resulting in a smaller portion of the inundated area in the high hazard category.

Research paper thumbnail of Retroceso de glaciares en el Perú: consecuencias sobre los recursos hídricos y los riesgos geodinámicos

Bulletin de l’Institut français d’études andines

Research paper thumbnail of Gestión del agua para enfrentar el cambio climático : propuesta de gestión del agua como medida importante de adaptación al cambio climático en Ancash

Research paper thumbnail of Balances de glaciares y clima en Bolivia y Peru: impacto de los eventos ENSO

Bull. Inst. fr. études …, 1995

La reconstrucción del balance hidrológico a partir de datos hidrométricos del glaciar de Zongo (C... more La reconstrucción del balance hidrológico a partir de datos hidrométricos del glaciar de Zongo (Cordillera Real de Bolivia), así como la aplicación del modelo lineal (Lliboutry) sobre los datos de balance de los glaciares Yanamarey y Uruashraju (Cordillera Blanca del Perú), ofrecen la posibilidad de disponer de series de 15-20 años de balance de masa. Analizando paralelamente los datos recogidos en estaciones meteorológicas cercanas, se puede evidenciar el rol de las temperaturas en la determinación de estos balances. La variabilidad de las temperaturas depende de una manera estrecha de los eventos ENSO (El Niño Southem Oscillation): durante estos eventos, las temperaturas máximas y mínimas aumentan sensiblemente y esto afecta el término ablación del balance de masa. Se verifica en estas series de 20 años que todos los años ENSO estén asociados a balances negativos. Durante la mayoría de los eventos ENSO, en el sur de Perú y en Bolivia, se produce una reducción de las precipitaciones, lo que contribuye a acentuar el efecto ENSO sobre los balances. Estos acontecimientos tienen una influencia importante sobre la evolución actual de los glaciares andinos, caracterizada por un retroceso rápido.

Research paper thumbnail of High Mountains Adaptation Partnership

This report was produced for review by the United States Agency for International Development (US... more This report was produced for review by the United States Agency for International Development (USAID). It was prepared by The University of Texas at Austin and The

Research paper thumbnail of Climatic extreme events combine with impacts of gradual climate change: recent evidence from the Andes and the Alps

Research paper thumbnail of Glacier recession and water resources in Peru’s Cordillera Blanca

The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in comple... more The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on the watershed. The retreat influence on discharge will be more pronounced during the dry season than at other periods of the year. At La Balsa, which measures discharge from the upper Río Santa, the glacier retreat could lead to a decrease in dry-season average discharge of 30%.

Research paper thumbnail of Glacier recession and water resources in Peru’s Cordillera Blanca

Journal of Glaciology, 2012

The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in comple... more The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on the watershed. The retreat influence on discharge will be more pronounced during the dry season than at other periods of the year. At La Balsa, which measures discharge from the upper Río Santa, the glacier retreat could lead to a decrease in dry-season average discharge of 30%.

Research paper thumbnail of Reducing risks from hazardous glacier lakes in the Cordillera Blanca (Peru): Six decades of experience and perspectives for the future

Research paper thumbnail of Modeling a glacial lake outburst flood process chain: the case of Lake Palcacocha and Huaraz, Peru

Hydrology and Earth System Sciences, 2016

One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk o... more One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of glacial lake outburst floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on 13 December 1941, killing about 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and preliminary hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5 to 3 × 10 6 m 3 were simulated, and two scenarios of 15 and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming moraine. Despite very high discharge rates (up to 63.4 × 10 3 m 3 s −1), the erosion from the overtopping wave did not result in failure of the damming moraine when simulated with a hydromorphodynamic model using excessively conservative soil characteristics that provide very little erosion resistance. With the current lake level, all three avalanche events result in inundation in Huaraz due to wave overtopping, and the resulting preliminary hazard map shows a total affected area of 2.01 km 2 , most of which is in the high hazard category. Lowering the lake has the potential to reduce the affected area by up to 35 %, resulting in a smaller portion of the inundated area in the high hazard category.

Research paper thumbnail of Retroceso de glaciares en el Perú: consecuencias sobre los recursos hídricos y los riesgos geodinámicos

Bulletin de l’Institut français d’études andines

Research paper thumbnail of Gestión del agua para enfrentar el cambio climático : propuesta de gestión del agua como medida importante de adaptación al cambio climático en Ancash

Research paper thumbnail of Balances de glaciares y clima en Bolivia y Peru: impacto de los eventos ENSO

Bull. Inst. fr. études …, 1995

La reconstrucción del balance hidrológico a partir de datos hidrométricos del glaciar de Zongo (C... more La reconstrucción del balance hidrológico a partir de datos hidrométricos del glaciar de Zongo (Cordillera Real de Bolivia), así como la aplicación del modelo lineal (Lliboutry) sobre los datos de balance de los glaciares Yanamarey y Uruashraju (Cordillera Blanca del Perú), ofrecen la posibilidad de disponer de series de 15-20 años de balance de masa. Analizando paralelamente los datos recogidos en estaciones meteorológicas cercanas, se puede evidenciar el rol de las temperaturas en la determinación de estos balances. La variabilidad de las temperaturas depende de una manera estrecha de los eventos ENSO (El Niño Southem Oscillation): durante estos eventos, las temperaturas máximas y mínimas aumentan sensiblemente y esto afecta el término ablación del balance de masa. Se verifica en estas series de 20 años que todos los años ENSO estén asociados a balances negativos. Durante la mayoría de los eventos ENSO, en el sur de Perú y en Bolivia, se produce una reducción de las precipitaciones, lo que contribuye a acentuar el efecto ENSO sobre los balances. Estos acontecimientos tienen una influencia importante sobre la evolución actual de los glaciares andinos, caracterizada por un retroceso rápido.

Research paper thumbnail of High Mountains Adaptation Partnership

This report was produced for review by the United States Agency for International Development (US... more This report was produced for review by the United States Agency for International Development (USAID). It was prepared by The University of Texas at Austin and The

Research paper thumbnail of Climatic extreme events combine with impacts of gradual climate change: recent evidence from the Andes and the Alps

Research paper thumbnail of Glacier recession and water resources in Peru’s Cordillera Blanca

The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in comple... more The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on the watershed. The retreat influence on discharge will be more pronounced during the dry season than at other periods of the year. At La Balsa, which measures discharge from the upper Río Santa, the glacier retreat could lead to a decrease in dry-season average discharge of 30%.

Research paper thumbnail of Glacier recession and water resources in Peru’s Cordillera Blanca

Journal of Glaciology, 2012

The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in comple... more The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on the watershed. The retreat influence on discharge will be more pronounced during the dry season than at other periods of the year. At La Balsa, which measures discharge from the upper Río Santa, the glacier retreat could lead to a decrease in dry-season average discharge of 30%.