Glacial lake outburst flood risk in the Bolivian Andes

The Bolivian Andes have experienced sustained and widespread glacier area reduction and volume loss in recent decades. This study finds that from 1986 to 2018 glacier areas have shrunk from 529 km2 to 281 km2 (49 %) in the Bolivian Cordillera Oriental. Glacier melting and recession has been accompanied by the development of proglacial lakes, which can pose a glacial lake outburst flood (GLOF) risk to downstream communities. Therefore, glacier bed topographies were extracted and illustrate the potential development of 68 future lakes. Eight of these lakes possess populations downstream. A simple geometric model (MC-LCP) was used to model GLOFs from these potential future lakes, illustrating that ~1100 to ~2900 people could be affected by flooding if these lakes were to appear and to burst. The rest of this work is dedicated on the estimation of the risk from current, already existing lakes. Multi- Criteria Decision Analysis (MCDA) was used to rapidly identify potentially dangerous proglacial lakes in regions around the world without existing tailored GLOF risk assessments, where a range of proglacial lake types exist, and where field data are sparse or non-existent. After testing the robustness of the MCDA model against a number of past GLOFs, it was applied to the Bolivian Cordillera Oriental. From the 25 lakes possessing populations downstream, 3 lakes were found to pose ‘medium’ or ‘high’ risk, and required further detailed investigation. Since no attempt has yet been made to model GLOF inundation downstream from these proglacial lakes, 2m resolution DEMs were generated from stereo and tri-stereo SPOT 6/7 satellite images to drive a hydrodynamic model (HEC-RAS 5.0.3) of GLOF flow. The model was tested against field observations of a 2009 GLOF from Keara, in the Cordillera Apolobamba, and was shown to reproduce realistic flood depths and inundation. The model was then used to model GLOFs from Pelechuco lake (Cordillera Apolobamba) and Laguna Arkhata and Laguna Glaciar (Cordillera Real). In total, ~1100 to ~2200 people could be directly affected by outburst flooding

Glacier change and glacial lake outburst flood risk in the Bolivian Andes

Glaciers of the Bolivian Andes represent an important water resource for Andean cities and mountain communities, yet relatively little work has assessed changes in their extent over recent decades. In many mountain regions, glacier recession has been accompanied by the development of proglacial lakes, which can pose a glacial lake outburst flood (GLOF) hazard. However, no studies have assessed the development of such lakes in Bolivia despite recent GLOF incidents here. Our mapping from satellite imagery reveals an overall areal shrinkage of 228.1 ± 22.8 km2 (43.1 %) across the Bolivian Cordillera Oriental between 1986 and 2014. Shrinkage was greatest in the Tres Cruces region (47.3 %), followed by the Cordillera Apolobamba (43.1 %) and Cordillera Real (41.9 %). A growing number of proglacial lakes have developed as glaciers have receded, in accordance with trends in most other deglaciating mountain ranges, although the number of ice-contact lakes has decreased. The reasons for this are unclear, but the pattern of lake change has varied significantly throughout the study period, suggesting that monitoring of future lake development is required as ice continues to recede. Ultimately, we use our 2014 database of proglacial lakes to assess GLOF risk across the Bolivian Andes. We identify 25 lakes that pose a potential GLOF threat to downstream communities and infrastructure. We suggest that further studies of potential GLOF impacts are urgently required

Modelling glacial lake outburst flood impacts in the Bolivian Andes

The Bolivian Andes have experienced sustained and widespread glacier mass loss in recent decades. Glacier recession has been accompanied by the development of proglacial lakes, which pose a glacial lake outburst flood (GLOF) risk to downstream communities and infrastructure. Previous research has identified three potentially dangerous glacial lakes in the Bolivian Andes, but no attempt has yet been made to model GLOF inundation downstream from these lakes. We generated 2-m resolution DEMs from stereo and tri-stereo SPOT 6/7 satellite images to drive a hydrodynamic model of GLOF flow (HEC-RAS 5.0.3). The model was tested against field observations of a 2009 GLOF from Keara, in the Cordillera Apolobamba, and was shown to reproduce realistic flood depths and inundation. The model was then used to model GLOFs from Pelechuco lake (Cordillera Apolobamba) and Laguna Arkhata and Laguna Glaciar (Cordillera Real). In total, six villages could be affected by GLOFs if all three lakes burst. For sensitivity analysis, we ran the model for three scenarios (pessimistic, intermediate, optimistic), which give a range of ~ 1100 to ~ 2200 people affected by flooding; between ~ 800 and ~ 2100 people could be exposed to floods with a flow depth ≥ 2 m, which could be life threatening and cause a significant damage to infrastructure. We suggest that Laguna Arkhata and Pelechuco lake represent the greatest risk due to the higher numbers of people who live in the potential flow paths, and hence, these two glacial lakes should be a priority for risk managers

Capacity management of migrant accommodation centers using approximate dynamic programming

Irregular migration has become a major macro-economic and political challenge. Due to rising political conflicts and income inequality across the world, the number of migrants is expected to increase exponentially over the coming decade. Thus, it is of critical importance to effectively use the limited resources allocated to humanitarian operations for irregular migration. In this paper we model the problem of capacity management and migrant transfers within a network of migrant accommodation centres with stochastic dynamic programming. Our study extends the literature on stochastic modelling and humanitarian operations by applying Approximate Dynamic Programming (ADP) into a new context. The model is translatable in other similar migratory routes and locations around the world where governments need to deal with uncertain numbers of irregular migrants. We test our approach on five Greek islands which have been the main migrant arrival points during the European Migrant Crisis. The results show that ADP provides a better computational performance than a simple myopic heuristic. The sensitivity analysis gives insights to the decision-makers about the impact of parameter values on the policies

Assessing glacial lake outburst flood risk.

Glaciers across the world are thinning and receding in response to atmospheric warming. Glaciers tend to erode subglacial basins and deposit eroded materials around their margins as lateral-frontal terminal moraines. Recession into these basins and behind impounding moraines causes meltwater to pond as proglacial and supraglacial lakes. Consequently, there has been a general trend of increasing number and size of these lakes associated with glacier melting in many mountainous regions around the globe, in the last 30 years. Glacial lake outburst floods (GLOFs) then may occur where the glacial lake dam (ice, rock, moraine, or combination thereof) is breached, or overtopped, and thousands of people have lost their lives to such events in the last few decades, especially in the Andes and in the Himalaya. Given the ongoing and arguably increasing risk posed to downstream communities, and infrastructure, there has been a proliferation of GLOF studies, with many seeking to estimate GLOF hazard or risk in specific regions, or to identify ‘potentially dangerous glacial lakes’. Given the increased scientific interest in GLOFs, it is timely to evaluate critically the ways in which GLOF risk has been assessed previously, and whether there are improvements that can be made to the ways in which risk assessment is achieved. We argue that, whilst existing GLOF hazard and risk assessments have been extremely valuable they often suffer from a number of key shortcomings that can be addressed by using different techniques as multi-criteria decision analysis and hydraulic modelling borrowed from disciplines like engineering, remote sensing and operations research

Volumetric changes of glaciers in the Bolivian Andes between 1986 and 2017

Glaciers represent an important water resource for Andean cities and mountain communities. However, a recent study has shown that Bolivian glaciers have shrunk by _43% in area over the last _30 years. If current rates of glacier recession are sustained then there could be potentially important consequences for downstream water supply, especially during the dry season. A first step in assessing the severity of this problem is to estimate the current volume of glacier ice in Bolivia, and how this has changed over recent decades. Here, we use VOLTA (created by James and Carrivick, 2016 – Computers & Geosciences), an ArcGIS tool requiring only a Digital Elevation Model (DEM) and glacier outlines to give a first-order ice thickness estimate and therefore derive volume changes for the entire Bolivian Andes between 1986 and 2017. The VOLTA tool also models bed topography, which we use to make a preliminary assessment of the locations of subglacial overdeepennings, which will become loci for future proglacial lakes capable of generating glacial lake outburst floods (GLOFs) and storing meltwater

Remote assessment of glacial lake outburst flood risk using multi-criteria decision analysis

Glaciers across the world are thinning and receding in response to atmospheric warming. Glaciers tend to erode subglacial basins and deposit eroded materials around their margins as lateral-frontal terminal moraines. Recession into these basins and behind impounding moraines causes meltwater to pond as proglacial and supraglacial lakes. Consequently, there has been a general trend of increasing number and size of these lakes associated with glacier melting in many mountainous regions around the globe, in the last 30 years. Glacial lake outburst floods (GLOFs) then may occur where the glacial lake dam (ice, rock, moraine, or combination thereof) is breached, or overtopped, and thousands of people have lost their lives to such events in the last few decades, especially in the Andes and in the Himalaya. Given the ongoing and arguably increasing risk posed to downstream communities, and infrastructure, there has been a proliferation of GLOF studies, with many seeking to estimate GLOF hazard or risk in specific regions, or to identify ’potentially dangerous glacial lakes’. Given the increased scientific interest in GLOFs, it is timely to evaluate critically the ways in which GLOF risk has been assessed previously, and whether there are improvements that can be made to the ways in which risk assessment is achieved. We argue that, whilst existing GLOF hazard and risk assessments have been extremely valuable they often suffer from a number of key shortcomings that can be addressed by using different techniques as multi-criteria decision analysis and hydraulic modelling borrowed from disciplines like engineering, remote sensing and operations research

Glacial lake outburst flood risk in the Bolivian Andes

Glaciers of the Bolivian Andes have experienced areal shrinkage of _43% in the last three decades, which has been accompanied by the development of proglacial lakes, some of which could generate glacial lake outburst floods (GLOFs). We provide the first attempt to assess GLOF risk in Bolivia, and model potential GLOF inundation. There are _137 proglacial lakes in the Bolivian Andes, 25 of which have population and/or infrastructure downstream.We first developed a GLOF risk assessment strategy using Multi-Criteria Decision Analysis (MCDA) guidelines that could be used remotely and free-of-charge to identify glacial lakes that represent the greatest GLOF risk. This revealed that three lakes posed medium or high risk, and required further analysis. Secondly, we undertook a modelling study of potential GLOF inundation from these three lakes. This involved the generation of a 2m resolution Digital Elevation Model (DEM) from stereo and tri-stereo SPOT 6/7 satellite images; the 2D hydrodynamic model HEC-RAS 5.0.3 was used to model GLOF flow. The model was tested against field observations of a 2009 GLOF from Keara, in the Cordillera Apolobamba, and was shown to reproduce realistic flood depths and inundation. The model was then used to model GLOFs from Pelechuco lake (Cordillera Apolobamba), and Laguna Arkhata and Laguna Glaciar (Cordillera Real). In total, six villages could be affected by GLOFs if all three lakes were to burst. We ran the model for three scenarios (pessimistic, intermediate, optimistic) which give a range of 1589 and 2302 people affected by flooding; between 1107 and 2168 people would be exposed to damaging floods (flow depth _ 2m). We suggest that Laguna Arkhata and Pelechuco lake represent the greatest risk due to the higher numbers of people who live in the potential flood paths, and hence should be a priority for risk managers

Progress and challenges in glacial lake outburst flood research (2017–2021):a research community perspective

Glacial lake outburst floods (GLOFs) are among the most concerning consequences of retreating glaciers in mountain ranges worldwide. GLOFs have attracted significant attention amongst scientists and practitioners in the past 2 decades, with particular interest in the physical drivers and mechanisms of GLOF hazard and in socioeconomic and other human-related developments that affect vulnerabilities to GLOF events. This increased research focus on GLOFs is reflected in the gradually increasing number of papers published annually. This study offers an overview of recent GLOF research by analysing 594 peer-reviewed GLOF studies published between 2017 and 2021 (Web of Science and Scopus databases), reviewing the content and geographical focus as well as other characteristics of GLOF studies. This review is complemented with perspectives from the first GLOF conference (7-9 July 2021, online) where a global GLOF research community of major mountain regions gathered to discuss the current state of the art of integrated GLOF research. Therefore, representatives from 17 countries identified and elaborated trends and challenges and proposed possible ways forward to navigate future GLOF research, in four thematic areas: (i) understanding GLOFs - timing and processes; (ii) modelling GLOFs and GLOF process chains; (iii) GLOF risk management, prevention and warning; and (iv) human dimensions of GLOFs and GLOF attribution to climate change.Fil: Emmer, Adam. University of Graz; AustriaFil: Allen, Simon K.. Universitat Zurich; Suiza. Universidad de Ginebra; SuizaFil: Carey, Mark. University of Oregon; Estados UnidosFil: Frey, Holger. Universitat Zurich; SuizaFil: Huggel, Christian. Universitat Zurich; SuizaFil: Korup, Oliver. Universitat Potsdam; AlemaniaFil: Mergili, Martin. University of Graz; AustriaFil: Sattar, Ashim. Universitat Zurich; SuizaFil: Veh, Georg. Universitat Potsdam; AlemaniaFil: Chen, Thomas Y.. Columbia University; Estados UnidosFil: Cook, Simon J.. University Of Dundee; Reino Unido. Unesco. Centre For Water Law, Policy And Science; Reino UnidoFil: Correas Gonzalez, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Das, Soumik. Jawaharlal Nehru University; IndiaFil: Diaz Moreno, Alejandro. Reynolds International Ltd; Reino UnidoFil: Drenkhan, Fabian. Pontificia Universidad Católica de Perú; PerúFil: Fischer, Melanie. Universitat Potsdam; AlemaniaFil: Immerzeel, Walter W.. Utrecht University; Países BajosFil: Izagirre, Eñaut. Universidad del País Vasco; EspañaFil: Joshi, Ramesh Chandra. Kumaun University India; IndiaFil: Kougkoulos, Ioannis. American College Of Greece; GreciaFil: Kuyakanon Knapp, Riamsara. University of Oslo; Noruega. University of Cambridge; Estados UnidosFil: Li, Dongfeng. National University Of Singapore; SingapurFil: Majeed, Ulfat. University Of Kashmir; IndiaFil: Matti, Stephanie. Haskoli Islands; IslandiaFil: Moulton, Holly. University of Oregon; Estados UnidosFil: Nick, Faezeh. Utrecht University; Países BajosFil: Piroton, Valentine. Université de Liège; BélgicaFil: Rashid, Irfan. University Of Kashmir; IndiaFil: Reza, Masoom. Kumaun University India; IndiaFil: Ribeiro De Figueiredo, Anderson. Universidade Federal do Rio Grande do Sul; BrasilFil: Riveros, Christian. Instituto Nacional de Investigación En Glaciares y Ecosistemas de Montaña; PerúFil: Shrestha, Finu. International Centre For Integrated Mountain Development Nepal; NepalFil: Shrestha, Milan. Arizona State University; Estados UnidosFil: Steiner, Jakob. International Centre For Integrated Mountain Development Nepal; NepalFil: Walker-Crawford, Noah. Colegio Universitario de Londres; Reino UnidoFil: Wood, Joanne L.. University of Exeter; Reino UnidoFil: Yde, Jacob C.. Western Norway University Of Applied Sciences; Suiz

The State of Remote Sensing Capabilities of Cascading Hazards Over High Mountain Asia

Cascading hazard processes refer to a primary trigger such as heavy rainfall, seismic activity, or snow melt, followed by a chain or web of consequences that can cause subsequent hazards influenced by a complex array of preconditions and vulnerabilities. These interact in multiple ways and can have tremendous impacts on populations proximate to or downstream of these initial triggers. High Mountain Asia (HMA) is extremely vulnerable to cascading hazard processes given the tectonic, geomorphologic, and climatic setting of the region, particularly as it relates to glacial lakes. Given the limitations of in situ surveys in steep and often inaccessible terrain, remote sensing data are a valuable resource for better understanding and quantifying these processes. The present work provides a survey of cascading hazard processes impacting HMA and how these can be characterized using remote sensing sources. We discuss how remote sensing products can be used to address these process chains, citing several examples of cascading hazard scenarios across HMA. This work also provides a perspective on the current gaps and challenges, community needs, and view forward toward improved characterization of evolving hazards and risk across HMA