Recurring avalanche hazards at Birendra Lake, Manaslu region: Interdisciplinary insights from the April 21, 2024, avalanche event

Abstract

On 21 April 2024, a large ice-debris avalanche from the Manaslu Glacier surged into Birendra Lake, triggering overtopping and downstream flooding along the Budhi Gandaki River. Situated below the retreating glacier, Birendra Lake has become increasingly susceptible to avalanche-induced hazards, reflecting the region's shifting climatic pattern and steep topography. This study employed integrated avalanche hazards analysis based on observations, geo-morphological assessments, climatic and hydrological analysis, and community-based interaction to investigate the recurring avalanche hazards in the region and examine the drivers and impacts of the April event. Our findings highlight that rising temperatures, declining precipitation, glacier detachment, and steep and rugged terrain (>30° slopes) are key factors contributing to avalanche susceptibility. While local communities perceive avalanches as routine seasonal events, awareness of their cascading effects, such as lake surges and infrastructure disruption, remains limited. The April event also revealed critical institutional gaps, particularly the lack of real-time hazard information and communication capacity within the region’s only formal authority, the Samagaun Police Station. This study highlights the importance of developing localized early warning systems, establishing high-altitude monitoring infrastructure, and implementing community-engaged risk reduction strategies. Strengthening institutional preparedness and integrating scientific analysis with local knowledge are crucial to enhancing resilience. By positioning Birendra Lake as a sentinel site of Himalayan cryospheric vulnerability, this research advocates for co-designed, context-specific approaches to hazard mitigation in avalanche-prone mountain regions.