Remote Sensing Characterization of Glaciers in the N. Himachal Pradesh

Glaciers in high mountain Asia represent the largest volume of ice outside of the polar regions. They play an important role in the water resources of communities downstream and there has been recent dispute over the total amount of ice present how it is changing. The immense quantity of glaciers and variability of glacier types in the Himalayas coupled with the sparse amount of suitable satellite data limits the capability of conducting detailed and efficient remote sensing observations on a regional scale. This study aims to develop a semi-automated characterization of approximately 5,000 glaciers in the N. Himachal Pradesh region of India using multi-spectral data. We use an August 2002 Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image because of its small percentage of snow and cloud cover, and because it is acquired late in the summer allowing for delineation of ablation and accumulation zones. Glacier outlines from the GLIMS glacier database for this region comprise total glacier area including debris covered ice regions. We outline the accumulation (snow-covered) region for each glacier exploiting the high reflectance value of snow compared to ice and debris. We further outline debris-free, bare-ice using a threshold on a ratio image of ETM+ bands 4 and 5. Subtracting this region from the GLIMS outlines leaves us with the debris-covered ice region. Using our resulting ablation and accumulation areas, we compute the area-accumulation ratio (AAR) for the many glaciers in our region. These data are compared to mean aspect, mean elevation, glacier size, percentage of debris cover, and mean equilibrium line altitude (ELA) for each glacier. This study hopes to contribute to and improve on glacier databases for the Himalayan region and to advance glacier analyses using remote sensing data. A possible future aim is to identify benchmark glaciers which can be used for detailed future study.