Hazard assessment of a pair of glacial lakes in Nepal Himalaya: Unfolding combined outbursts of Upper and Lower Barun

Due to climate change, the future Glacial Lake Outburst Flood (GLOF) risk is more likely in the Himalayas. Despite several GLOF studies, little attention has been given to the combined or cascading GLOF events. The researchers chose Upper and Lower Barun glacial lakes as a pilot study due to the region’s increasing population and hydropower investments and the possible outbursts of upper-lower glacial lakes considering combination of full and partial breach scenarios.

The study finds that based on the observations, the glaciers in the study area shrank by 33 km², and the two glacial lakes expanded by 2.06 km² between 1976 and 2020. The modeling result show that the combined flow from both lakes could reach over 85 km inundating 60 buildings, motorable bridges, and infrastructures of Arun hydropower along the river course. The study insights can be helpful for effectively planning and formulating various disaster risk reduction initiatives to mitigate the likely effects of glacial lake(s) outbursts.