Abstract ID: 3.10383 | Accepted as Talk | Talk/Oral | TBA | TBA

Due to climate change, Bhutan’s magnificent glaciers, which are the lifeblood of the country, are slowly disappearing. These vast chunks of ice serve as nutrients for ecosystems, water crops and generate hydroelectricity. This research utilizes geoinformatics techniques to assess the health of Thorthormi Glacier which is an important source of water and has the potential to cause devastating Glacial Lake Outburst Floods (GLOFs) in Bhutan. A technique called Accumulation Area Ratio (AAR) was used to determine the glacier mass balance of Thorthomi tsho from year 2015 to 2023. AAR is ratio of accumulated area of glacier to the total area of the glacier (Cogley et al., 2011). This technique involves the use of Sentinel images and over laying the images to produce Red, Green and Blue (RGB) composite. From this RGB composite, Equilibrium Line Altitude(ELA) was delineated to get AAR. The declining nature of Thorthormi’s AAR indicates more melting of glacier. The research examined meltwater from the glacier that feeds Thorthormi Lake so as to better understand the vulnerability of GLOFs or glacial lake outbursts in this area. Thorthomi glacier is losing more mass than it gains, as a result, the glacier cannot regenerate itself. Due to the melting of Thorthomi glacier, the proglacier lake beneath it, is growing bigger. It indicates that there could be a possible hazard for a catastrophic GLOF soonest possible. A sudden breach of the lake’s dam could release a massive amount of water, ice, and debris, causing widespread destruction and endangering lives downstream(Sharma et al., 2018). To determine the GLOF susceptibility of the area downstream, hydrological modelling was performed, which make use of lakes volume and its peak discharge. Modified Normalized Difference Water Index was used to delineate the area of Thorthomi lake. The area is then used to determine the volume of the lake. Based on the volume, peak discharge and with the help of a Digital Elevation Model (DEM), the susceptibility map was produced for each zone of the study area.