Global risk of glacial lake outburst floods : hazard, exposure, and vulnerability

Abstract

Globally since 1990, glacial lakes have grown rapidly in response to atmospheric driven deglaciation. Glacial lakes represent a major natural hazard, where dam failure can lead to the sudden release of water and sediment known as Glacial Lake Outburst Floods (GLOFs), causing significant downstream and transnational impacts. Concurrently, exposure of populations and infrastructure to GLOF hazards in high-mountain regions has increased, whilst vulnerability has also changed. Despite this, the global distribution of GLOF risk has never been quantified, nor have GLOF risk drivers been evaluated. This thesis aims to quantify the spatial and temporal variation in GLOF risk at a global scale, and assess the roles of hazard, exposure, and vulnerability as risk drivers. Results show as of 2020 15 million people are at risk of GLOFs. High Mountain Asia has the highest GLOF risk in 2020. Populations here live the closest to glacial lakes globally, with ~1 million people living within 10 km of a glacial lake. Risk in the Andes is increasing rapidly, yet a lack of long-term, complete databases hinders the analysis of past and future GLOF trends. With a long history of GLOF disasters, increasing risk here is concerning, and I strongly suggest the region be targeted for more detailed study. Critically, results show it is not the regions with the largest, most numerous glacial lakes with the highest GLOF risk, instead, the number of people at risk and their capacity to cope plays a vital role. This reaffirms the importance of holistic risk assessments. Finally, this thesis shows GLOF risk will continue to evolve spatially and temporally over the coming decades, driven by hazard and exposure changes. This thesis highlights the complexity of GLOF risk and indicates mitigation will require bespoke, multidisciplinary, and transboundary solutions. By identifying high risk regions and risk drivers, this work could help refine disaster risk reduction strategies and future research priorities to prevent future GLOF disasters.