Abstract
Glacial lake outburst floods (GLOFs) are a major concern in the Himalaya and on the Tibetan Plateau (TP), where several disasters occurring over the past century have caused significant loss of life and damage to infrastructure. This study responds directly to the needs of local authorities to provide guidance on the most dangerous glacial lakes across TP where local monitoring and other risk reduction strategies can subsequently be targeted. Specifically, the study aims to establish a first comprehensive prioritisation ranking of lake danger for TP, considering both the likelihood and possible magnitude of any outburst event (hazard), and the exposure of downstream communities. A composite inventory of 1,291 glacial lakes (>0.1 km2) was derived from recent remote sensing studies, and a fully automated and object assessment scheme was implemented using customised GIS tools. Based on four core determinates of GLOF hazard (lake size, watershed area, topographic potential for ice/rock avalanching, and dam steepness), the scheme accurately distinguishes the high to very high hazard level of 19 out of 20 lakes that have previously generated GLOFs. Notably, 16% of all glacial lakes threaten human settlements, with a hotspot of GLOF danger identified in the central Himalayan counties of Jilong, Nyalam, and Dingri, where the potential trans-boundary threat to communities located downstream in Nepal is also recognised. The results provide an important and object scientific basis for decision-making, and the methodological approach is ideally suited for replication across other mountainous regions where such first-order studies are lacking.
Highlights
Glacial lake outburst floods (GLOFs) refer to the sudden discharge of a water reservoir that has formed either underneath, at the side, in front, within, or on the surface of a glacier, and related dam structures can be composed of ice, moraine or bedrock
Class breaks are identified that best group similar values and that maximize the differences between classes. This is illustrative only to inform the prioritization of GLOF hazard and danger across the Tibetan Plateau (TP), and specific classes cannot be directly compared with categories used in other studies or regions
In the Boshula mountains, southeast TP, artefacts in the topographic data affected the modelling of GLOF paths in some localised areas, meaning GLOF danger may have been underestimated in this region where at least 3 historical outburst events have been recorded [19], and several lakes with very high hazard levels are located (Fig. 3b)
Summary
Glacial lake outburst floods (GLOFs) refer to the sudden discharge of a water reservoir that has formed either underneath, at the side, in front, within, or on the surface of a glacier, and related dam structures can be composed of ice, moraine or bedrock. Across high mountain Asia, and elsewhere in the world, considerable focus has been on flood hazard associated with the catastrophic failure of moraine dammed lakes [1,2,3,4]. Failure of moraine dammed lakes occurs when the material strength of the dam structure is exceeded by driving forces, including the weight of the impounded water mass, shear stresses from seepage, and overtopping or additional momentum from displacement waves [6]. Displacement waves from large impacts of ice or rock have contributed to over 50% of catastrophic moraine dam failures [2,7]. Approaches to GLOF hazard assessment must consider large spatial scales, not restricted by administrative or political boundaries
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
