Public warning and evacuation experiences during recent GLOF events (2019 and 2023) and recommendations for future preparedness: Insights from Lunana, Bhutan

Early warning systems (EWS) are essential for reducing loss of life during the event of glacial lake outburst floods (GLOFs). However, the efficacy of EWS is contingent on factors including warning dissemination and community response. Despite the crucial role of EWS, there remains a paucity of studies examining community experiences with GLOF EWS, which are imperative for improving existing systems. Using surveys, key informant interviews and focus groups, this study offers insights into warning dissemination (including sources and channels of communication) and evacuation during recent (in 2019 and 2023) GLOF events in Lunana, Bhutan. Our analysis showed that environmental cues, such as unusually loud river sounds and ground vibrations, were the main sources of initial warning during past GLOF events. Mobile phone calls from friends and family also emerged as common channels for disseminating both initial and subsequent warning messages. Participants described evacuation during recent events as challenging and uncoordinated, with some people lacking pre-prepared essential items and facing difficult conditions at evacuation sites, including exposure to extreme cold and limited shelter. We first recommend strengthening existing GLOF EWS, making it more community-based, and diversifying communication response channels and sources, particularly through resilient mobile phone-based communication. Second, we recommend enhancing people’s resilience to future GLOFs by expanding existing advocacy programmes toward building people’s response capability, including regular mock drills, evacuation preparedness training, and fit-for-purpose, co-designed shelters at evacuation sites.