Feature tracking analysis of Bechung glacier dynamics using Landsat imagery: surface displacement and velocity assessment in Bhutan

Accelerated glacier retreat across the Himalayan range has emerged as one of the most pronounced indicators of regional climate change, with significant implications for downstream water security and natural hazard risks in South Asian Mountain communities. In Bhutan, glacier dynamics directly influence national water resources, hydropower generation, and agricultural productivity, yet comprehensive quantitative assessments of individual glacier behavior remain limited. This knowledge gap constrains evidence-based adaptation planning and natural hazard mitigation strategies in one of the world's most glaciated and climate-vulnerable regions. This study presents the first comprehensive 22-year analysis of Bechung Glacier dynamics using advanced feature tracking methods applied to multi-temporal Landsat 7, 8, and 9 imagery (2000–2022). We employed normalized cross-correlation algorithms to derive high-precision surface displacement fields, velocity patterns, and ice thickness distributions using Glen's flow law parameterization. Results indicate mean surface velocities of 6.9 ± 0.5 m/yr, with maximum displacement rates of 13.8 m/yr observed in the upper ablation zone, values consistent with other debris-covered Himalayan glaciers. Ice thickness estimates range from 0 to 225 ± 15 m, with maximum thickness concentrated along the central flowline. Bed topography analysis revealed three distinct over-deepened basins with potential for future glacial lake formation, the largest exhibiting a maximum depth of 112 m and representing significant GLOF hazard potential. The 22-year velocity record provides unprecedented temporal resolution for monitoring glacier response to regional climate variability in the Eastern Himalayas. These findings advance quantitative understanding of Himalayan glacier dynamics and provide essential baseline data for improved hydrological modeling and evidence-based natural hazard risk assessment in climate-vulnerable mountain regions.