Abstract ID: 3.11453 | Accepted as Poster | Poster | TBA | TBA

Glacial lakes in the high mountain regions across the world are growing in both numbers and areas. Many of these glacial lakes have produced glacial lake outburst floods some of which were devastating, resulting in numerous deaths and destructions in the downstream communities. Amidst increasing hazards from glacial lakes, settlements in vulnerable downstream area continue to expand, thereby exacerbating GLOF risk. Traditionally, the potentially dangerous glacial lakes were primarily defined based on the likelihood of producing GLOF using attributes such as topographic features surrounding the lakes. However, this approach of defining potentially dangerous glacial lake is incomplete as it does not provide any information about how glacial lake impact downstream settlement. To this end, this study redefined potentially dangerous glacial lakes in Bhutan based on hydrodynamic hazard mapping and downstream exposure data. As a result, we have produced a hazard map for all glacial lakes in Bhutan with an area greater than 0.05 km2 and which are within 1 km of the glacier terminus. Our result shows that approximately 20882 people, 2620 buildings, 270 km of road, 402 bridges and 169 hectares of farmland are exposed to GLOF in Bhutan. Thorthormi Tsho in Lunana, Punatsangchu basin is the most dangerous glacial lake. We also identified five other lakes as highly dangerous which are distributed across the Wangchu (2), Chamkharchu (2), and Punatsangchu (1) basins. Among downstream settlements, Chhoekhor Gewog in Bumthang was found to have the highest level of GLOF danger, followed by Bumthang town, Punakha town, and Lunana. Furthermore, nine additional gewogs and towns were classified as having a high level of GLOF danger. These findings highlight the urgent need to strengthen and expand the coverage of the early warning network to include all high GLOF danger gewogs and towns, thereby enhancing disaster preparedness and risk mitigation efforts. This study underscores the importance of integrating hydrodynamic hazard mapping and downstream exposure data to improve the accuracy of GLOF risk assessments and inform targeted mitigation strategies in vulnerable regions.