Modelling glacial lake outburst flood impacts in the Bolivian Andes

Ioannis Kougkoulos,Simon J Cook,Elias Symeonakis,Leon J Clarke,Kathleen Nesbitt,Jason M Dortch,Laura A Edwards

doi:10.1007/s11069-018-3486-6

Abstract

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.

Highlights

Climate change is driving glacier mass loss in most parts of the world (Zemp et al 2015)
Subsequent work by Kougkoulos et al (2018) developed a glacial lake outburst flood (GLOF) risk assessment technique based on the use of multicriteria decision analysis (MCDA), which was applied to the lake inventory of Cook et al (2016)
For each of the three lakes and potential GLOF runout zones, we identified approximately thirty tie points over the pairs of images used for each DEM in order to calculate shift parameters between images at each tie point, obtaining an overall root-mean-square error (RMSE) of less than 1 pixel (< 1.5 m)

Summary

Introduction

Climate change is driving glacier mass loss in most parts of the world (Zemp et al 2015). There has been growing concern about the impacts of glacial lake outburst floods (GLOFs) on downstream communities and infrastructure in many deglaciating regions worldwide Recent work by Cook et al (2016) found that glacier area in the Bolivian Andes had reduced by ~ 43% from 1986 to 2014, leading to an increase in the number and areal coverage of proglacial lakes. They undertook a rudimentary assessment of GLOF risk in the region, suggesting that 25 lakes could pose a risk to downstream communities. We aim to model potential GLOF inundation downstream from these three lakes and assess the possible impacts on downstream communities and infrastructure

Objectives

Results

Discussion

Conclusion