The disappearance of mountain glaciers and expansion of glacial lakes are amongst the most recognizable and dynamic impacts of global warming. Such new lakes bring opportunities (e.g., hydropower) but also pose significant threats, due to the increasing potential for catastrophic Glacial Lake Outburst Floods (GLOFs). This threat is most pronounced across high mountain Asia, where communities, transportation networks, and other vital infrastructure are exposed. This is particularly true for China, where many potentially dangerous lakes have been documented, and significant growth of these lakes has been noted over recent decades. In view of projected warming over the 21st century and continued retreat of glaciers, scientific attention has recently shifted beyond monitoring and assessment of the existing GLOF threat towards the anticipation of where new, potentially problematic lakes will form in the future. Such lakes will most likely develop in bedrock depressions or overdeepenings in the exposed glacier bed, and as such, methods have been developed to model bed topography and thereby identify where these new lakes will form. However, a key limitation remains that timing of the emergence and future evolution of glacial lakes is generally unconstrained for data-scarce mountain regions. This represents a major scientific challenge, as local climatological, geomorphological, and topographic conditions will lead to significant diversity in lake evolution. In addition, integrated approaches are yet to be developed which consider the full range of triggering processes that contribute to GLOF hazard both now, and in the future. Highly transient factors include the stability of surrounding ice and rock walls, the thawing of ice-cored moraine dams, and changes in heavy precipitation, snowmelt and faster runoff that may be expected in some deglaciated catchments.
The overall aim of the proposed study is to develop and implement a comprehensive methodological approach to investigate the recent and future evolution of glacial lakes and their related hazard potential in different climatological, geomorphological, and topographic settings. This will lead to improved understanding and prediction of lake formation, change in GLOF triggering processes, and change in hazard in downstream areas, as glaciers continue to retreat over the 21st century and beyond. The research methodology is centred on 7 work packages which bring together the complementary strengths of the partner institutions in the fields of remote sensing based analyses of the cryosphere, GIS-based modelling, and GLOF hazard assessment. Within three contrasting study regions in Tibet, reconstruction of the recent (since ca.1970) evolution of glacier thinning, retreat, and associated lake development will provide the basis for catchment-scale modelling of future changes. The integrated modelling approach will consider not only the expansion of existing lakes, but also the formation of new lakes in the exposed bed topography, and will investigate the corresponding increase in GLOF potential as key transient triggering processes evolve in a warmer climate. For selected critical lakes, both now, and in the future, complete lake outburst and flow modelling will be undertaken, providing a quantitative basis for assessing the change in downstream hazard.
The methodological approach will be optimised for outscaling to larger regions, recognising the urgent need for robust scientific information to support adaptation planning in response to the rapidly evolving GLOF threat across high mountain Asia. The exchange of knowledge between Swiss and Chinese partners will ensure that local scientists are best positioned to lead ongoing monitoring programs and further research activities in the region.
Principle Investigator：Yao Tandong
Project duration：2017.01-2020.12