Q1.a. Explain the causes of glacial lake outburst flood. 10 2025
Introduction
A Glacial Lake Outburst Flood is a sudden, catastrophic release of water from a glacial lake caused by failure of its natural dam (ice, moraine, or sediment). This phenomenon results from dam instability, triggering events, and downstream vulnerability, intensified by climate change and differential adaptation capacity between regions.
1. Dam Instability — Primary Cause
- Moraine dams: Composed of loose, unconsolidated glacial debris, inherently unstable under rising water pressure and prone to sudden breach.
- Ice dams: Weakened by thermal melting, internal fracturing, and hydrostatic stress from rising lake levels.
2. Triggering Mechanisms
- Avalanches and rockfalls into the lake generating displacement waves that overtop and breach dams.
- Glacial surges and ice calving adding water volume and mechanical stress.
- Heavy rainfall and rapid snowmelt raising lake levels and hydrostatic pressure.
- Seismic activity fracturing or destabilizing dam structures.
- Subglacial volcanic eruptions rapidly melting ice, producing large surges (jökulhlaups).
- Human activities—deforestation, land-use change, and greenhouse gas emissions—accelerating glacier melt and slope instability.
3. Theoretical Frameworks
Disaster and Risk Theory:
- Gilbert White’s foundational principle states: “Floods are an act of God, but flood losses are largely an act of man.” White’s work on floodplain adjustment emphasizes that structural defenses increase hazard exposure by encouraging occupance in vulnerable areas; this applies directly to glacial lake hazard zones where false confidence in dam stability increases downstream risk.
- Ulrich Beck’s Risk Society concept notes that “risk is a systematic way of dealing with hazards and insecurities induced by modernization itself,” framing GLOFs within broader climate change and infrastructure vulnerability contexts where industrial societies face amplified hazards from their own modifications.
Glacial Lake Formation and Climate Cycles:
- L.C. Peltier’s Periglacial Cycle framework (1950) describes cycles of glacial advance and retreat tied to climate fluctuations, establishing the foundation for understanding how glacier–climate interactions drive lake formation. His model emphasizes recurring cycles of accumulation, ablation, and periglacial processes that regulate meltwater generation and glacial lakes.
Dam Governance and Development Inequality:
- Elinor Ostrom’s Common Pool Resource governance principles highlight how monitoring, collective-choice arrangements, and nested governance institutions enable sustainable management. Developed nations typically implement these principles through robust monitoring networks and early-warning systems, while developing countries often lack such infrastructure, increasing vulnerability.
- Martha Nussbaum’s capabilities approach emphasizes equity in disaster resilience, arguing that communities must possess not only resources but also capabilities (access to information, decision-making power, livelihood security) to adapt. This framework reveals how GLOF vulnerability is unequally distributed, with mountain communities in developing regions lacking adaptive capacity.
4. Case Studies
- Chorabari Lake, Uttarakhand, India (2013): A moraine-dam breach caused catastrophic flooding in the Mandakini River valley, killing thousands and destroying settlements. The event illustrates how rapid glacier melt (driven by warming) enlarges lakes beyond dam capacity, a pattern now repeating across the Himalayas as climate changes.
- Grímsvötn, Iceland (1996): A subglacial volcanic eruption triggered a jökulhlaup releasing approximately six thousand cubic meters of water per second, destroying bridges and infrastructure downstream. This demonstrates volcanic–glacial interaction and showcases developed-nation preparedness with early warnings and evacuation protocols.
- South Lhonak Lake, Sikkim, India (2023): Rising lake volume destabilized a moraine dam, breaching downstream and damaging the Chungthang hydroelectric dam. This case exemplifies how developing regions with critical infrastructure face compounded risk from both GLOFs and insufficient early-warning capacity.
5. Development Disparities
Developed nations employ real-time lake monitoring, hydrodynamic modeling, and community alert systems (Beck’s modernity managing its own risks). Developing countries, constrained by limited funding and technical capacity, struggle with dam surveillance and evacuation preparedness, reflecting Nussbaum’s capability inequalities and White’s principle that social structures amplify losses.
Conclusion
GLOFs emerge from unstable natural dams, triggering events, and amplified downstream exposure. Integrating disaster theory, glacial-cycle understanding, and governance frameworks reveals how GLOF hazards are shaped not only by physics but by social choices, infrastructure inequity, and climate-driven glacier dynamics. Effective mitigation requires bridging development gaps through adaptive governance and community-centered resilience.
Sources
[1] Gilbert White https://www.aag.org/memorial/gilbert-white/
[2] Risk society – Wikipedia https://en.wikipedia.org/wiki/Risk_society
[3] Periglacial Processes | L.C Peltier(1950) https://geographyebooks.com/periglacial-cycle-of-erosion-periglacial-landforms-periglacial-processes-l-c-peltier-1950/
[4] Gilbert F. White https://en.wikipedia.org/wiki/Gilbert_F._White
[5] Notes: Risk Society by Ulrich Beck https://adarshbadri.me/politics-society/notes-risk-society-by-ulrich-beck/
[6] William Richard Peltier – Wikipedia https://en.wikipedia.org/wiki/William_Richard_Peltier
[7] Gilbert F. White – National Science and Technology Medals … https://nationalmedals.org/laureate/gilbert-f-white/
[8] Could somebody please help to explain the concept of a ‘risk society’ to me? I’ve been studying for weeks. https://www.reddit.com/r/sociology/comments/fp9xng/could_somebody_please_help_to_explain_the_concept/
[9] William Richard Peltier – Wikipedia https://en.wikipedia.org/wiki/Dick_Peltier
[10] Beyond bigger and better: Gilbert White and America’s new approach to floodplain management https://scholarsjunction.msstate.edu/cgi/viewcontent.cgi?article=1871&context=td
[11] Periglacial Cycle of Erosion | Periglacial Landforms |Periglacial Processes | L.C Peltier(1950) https://www.youtube.com/watch?v=tldauer3Ltk
[12] Elinor Ostrom – Wikipedia https://en.wikipedia.org/wiki/Elinor_Ostrom
[13] Capability approach https://en.wikipedia.org/wiki/Capability_approach
[14] PERIGLACIAL CYCLE OF EROSION https://www.youtube.com/watch?v=YCJYWZgvpSo
[15] [PDF] Prize Lecture by Elinor Ostrom https://www.nobelprize.org/uploads/2018/06/ostrom_lecture.pdf
[16] Martha Nussbaum: Capabilities Approach and Public Services https://raggeduniversity.co.uk/2022/09/28/martha-nussbaum-public-services/
[17] Periglacial Processes | L.C Peltier(1950) https://thegeoecologist.com/periglacial-cycle-of-erosion-periglacial-landforms-periglacial-processes-l-c-peltier1950/
[18] GOVERNING https://www.actu-environnement.com/media/pdf/ostrom_1990.pdf
[19] Human Rights and Human Capabilities https://journals.law.harvard.edu/hrj/wp-content/uploads/sites/83/2020/06/20HHRJ21-Nussbaum.pdf
[20] Peltier 1950 https://www.scribd.com/document/775899392/Peltier-1950
