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Part 1: Identifying potentially dangerous glacial lakes
Koshi Disaster Risk Reduction Knowledge Hub
Koshi Basin Initiative
19 November 2020
Kanchan Shrestha & Finu Maharjan
With global warming, most Himalayan glaciers are melting faster and rapidly losing ice mass. This has significantly raised the threat of glacial lake outburst floods (GLOFs) in the region. More than 45 GLOFs have been documented in the Eastern Himalaya alone (eastern Nepal; Bhutan; Northeast India; and Tibetan Autonomous Region, China). Most glacial lakes in the Himalaya are expanding rapidly, and GLOFs can be devastating for downstream communities, impacting infrastructure, settlements, livelihoods, and lives. And these impacts are very often transboundary in nature, especially in the Himalaya. More than 10 historical GLOF events that originated in the Tibet Autonomous Region, China, have killed hundreds of people and destroyed infrastructure and hydropower plants downstream in Nepal.
Lake inventories and assessments of change trends have to some extent helped in understanding lake dynamics and growth. But it is difficult to predict the exact factors that trigger a GLOF. Different researchers have applied different criteria to identify potentially dangerous glacial lakes (PDGLs) either for a specific lake or region, and to evaluate the risk assessment concerning downstream communities.
Existing criteria developed and adopted for the identification of PDGLs for specific lake type are sometimes not suitable for other lake types within the region. Thus, it is necessary to establish standardized criteria which can be applied to all types of glacial lakes in the Eastern Himalayan region. Using a common methodology to assess GLOF risk is critical for long-term monitoring and reducing risk.
We are conducting this consultation series with an interdisciplinary team of experts to jointly develop a standardized methodology for systematic GLOF risk assessment, which will identify PDGLs in the Eastern Himalaya and prioritize lakes by GLOF risk. This is the first consultation in the series and will happen in two parts. Part 1 will focus on standardization of the methodology for identifying PDGLs, and part 2 will focus on socioeconomic vulnerability and the risk assessment approach. The consultation is a joint effort of the Transboundary Working Group (TWG) on GLOFs within the Koshi Disaster Risk Reduction (DRR) Knowledge Hub, in collaboration with ICIMOD’s Cryosphere Initiative and Koshi Basin Initiative. The hub promotes transboundary collaboration and strengthens science–policy–practice linkages to build a resilient Koshi River basin.
The TWG on GLOFs will first get acquainted with the step-by-step approach of the criteria developed for the identification of PDGLs in the Eastern Himalaya. A session will be dedicated to brainstorming the importance of each of the physical and socioeconomic parameters and to developing a common understanding of the methodology for GLOF risk assessment. During the brainstorming session, the TWG will decide on the addition or exclusion of the parameters. The TWG will also discuss weighted scores for each parameter to determine the relative importance of the parameters in relation to the GLOF hazard.