160 glacial lake outburst floods (GLOFs) across the Tropical Andes since the Little Ice Age

Adam Emmer,Simon J Cook,Efrain Turpo,Hilbert Villafane,Henrry Garrido,Lucas Torres,Julia Araujo,John M Reynolds,Adriana Caballero,Sarah Shannon,Enver Melgarejo,Tito Tinoco,Ryan Wilson,Nebenka Apaza,David Garay,Joanne L Wood,Martin Mergili,Neil F Glasser,Stephan Harrison,Christian Riveros,Harrinson Jara ,Carlos A Martínez ,Christian Yarlequé ,Georgina L Bennett ,Alejandro Díaz‐Moreno ,Juan Torres ,C Poma

doi:10.1016/j.gloplacha.2021.103722

Abstract

Assessing the extent to which glacial lake outburst floods (GLOFs) are increasing in frequency in modern times and whether their incidence is driven by anthropogenic climate change requires historical context. However, progress on this issue is hampered by incomplete GLOF inventories, especially in remote mountain regions. Here, we exploit high-resolution, multi-temporal satellite and aerial imagery, and documentary data to identify GLOF events across the glacierized Cordilleras of Peru and Bolivia, using a set of diagnostic geomorphic features. A total of 160 GLOFs from 151 individual sites are characterised and analysed, tripling the number of previously reported events. We provide statistics on location, magnitude, timing and characteristics of these events with implications for regional GLOF hazard identification and assessment. Furthermore, we describe several cases in detail and document a wide range of process chains associated with Andean GLOFs. • Our inventory consists of 160 glacial lake outburst floods (GLOFs). • About two thirds of these have not been identified previously in the literature. • We analyze spatial and temporal patterns of GLOF occurrence. • We characterize pre-conditions, triggers and mechanisms of GLOFs.

Highlights

Glacial lake outburst floods (GLOFs) – sudden releases of water from glacial lakes – are among the most rapid and powerful geomorphic agents in deglaciating mountain regions, with released volumes and peak discharges far exceeding those from other types of flooding (Costa and Schuster, 1988; Evans and Clague, 1994; Carrivick and Tweed, 2016; Cook et al, 2018)
Our inventory contains a total of 160 glacial lake outburst floods (GLOFs) occurring from 151 individual lake sites across Peruvian (139 GLOFs from 131 lakes) and Bolivian Andes (21 GLOFs from 20 lakes; see Fig. 4)
We have created an inventory of GLOFs in the glacierized Cordilleras of Peru and Bolivia by the integration of in-depth literature review and analysis of documentary data, further enhanced by detailed geomor phological interpretation and analysis of remote sensing imagery with field validation

Summary

Introduction

Glacial lake outburst floods (GLOFs) – sudden releases of water from glacial lakes – are among the most rapid and powerful geomorphic agents in deglaciating mountain regions, with released volumes and peak discharges far exceeding those from other types of flooding (Costa and Schuster, 1988; Evans and Clague, 1994; Carrivick and Tweed, 2016; Cook et al, 2018). Some recent studies have demonstrated a decrease or stagnation in the frequency of such events in some parts of the world over recent decades (Carrivick and Tweed, 2016; Harrison et al, 2018; Veh et al, 2020), highlighting the complexity of understanding GLOF risk in these rapidly evolving landscapes. While global in ventories are valuable for deriving a broad appreciation of GLOF spatiotemporal dynamics, detailed studies focussed on a specific region (mountain range, country), which incorporate cross-checking against geomorphological evidence for past GLOFs, typically reveal missing data (Anacona et al, 2015; Emmer, 2017; Veh et al, 2019; Zheng et al, 2021)

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