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Lookup NU author(s): Sonam Rinzin, Professor Stuart DunningORCiD, Professor Rachel CarrORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Hazard and risk from glacial lake outburst floods (GLOFs) in Bhutan have traditionally been assessed with limited consideration of the downstream exposure and vulnerability associated with individual lakes. However, exposure and vulnerability are key components of risk, and when explicitly attributed to each lake, can provide a more robust basis for prioritising hazard investigations and mitigation efforts. We modelled hypothetical GLOF scenarios for all glacial lakes with an area greater than 0.05 km2 and located within 1 km of a glacier terminus. We then determined GLOF risk by explicitly accounting for downstream impacts using depth–velocity outputs at each exposed element affected by the simulated GLOF from each lake, as well as the vulnerability of the affected community. Our study shows that approximately > 11 000 people, > 2500 buildings, > 250 km of road, > 400 bridges and ∼ 20 km2 of farmland are exposed to potential GLOF in Bhutan. We classified lake130 (Thorthormi Tsho) as a very high hazard glacial lake in Bhutan, five lakes as high hazard and 22 other lakes as moderate hazard. Among these high hazard glacial lakes, three of them: lake93 (Phudung Tsho), lake251, and lake278 (Wonney Tsho) were not recognised as being high hazard in previous studies. Five downstream local government administrative units (LGUs) were associated with very high GLOF risk, while eight others are associated with high GLOF risk. Five of these very high and high risk LGUs had not been previously documented as being at risk from GLOF. Our study underscores the significance of integrating potential inundation mapping and downstream exposure data to define high hazard glacial lakes. We recommend strengthening and expanding the existing GLOF preparedness and risk mitigation efforts in Bhutan, particularly in the LGUs, as having high GLOF risk identified in this study, to reduce potential future damage and loss.
Author(s): Rinzin S, Dunning S, Carr RJ, Allen S, Wangchuk S, Sattar A
Publication type: Article
Publication status: Published
Journal: Natural Hazards and Earth System Sciences
Year: 2026
Volume: 26
Issue: 2
Pages: 1015-1037
Online publication date: 03/03/2026
Acceptance date: 19/01/2026
Date deposited: 05/03/2026
ISSN (print): 1561-8633
ISSN (electronic): 1684-9981
Publisher: Copernicus GmbH
URL: https://doi.org/10.5194/nhess-26-1015-2026
DOI: 10.5194/nhess-26-1015-2026
Data Access Statement: The HEC-RAS 2D model we used here for simulating glacial lake outburst modelling can be accessed at https://www.hec.usace.army.mil/ (last access: 1 October 2025). The AW3D30 DEMS used here can be downloaded from the OpenTopography – Find Topography Data at https://portal.opentopography.org/datasets (last access: 1 April 2024). Bhutan 2017 housing and census data can be downloaded from the National Statistical Bureau of Bhutan at https://www.nsb.gov.bt/ (last access: 1 April 2024). Landover and landuse data used in this study can be accessed at https://rds.icimod.org/ (last access: 1 April 2024). The OpenStreetMap data can be assessed at https://www.openstreetmap.org/relation/184629 (last access: 1 April 2024). GLOF hydraulic data for each glacial lake can be accessed through the web portal Himalayan Hazard: https://www.himalayanhazards.org/ (last access: 24 February 2026) upon publication of this article.
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