Long-Term Geospatial Observations of the Drang Drung and Pensilungpa Glaciers, North Western Himalaya, India, from 1976 to 2020

Abstract

Drang Drung and Pensilungpa are neighbouring glaciers in the western Himalayas, sharing the same meteorological conditions and climate zone. The Drang Drung glacier is a clean glacier, whereas the Pensilungpa glacier is notable for its considerable accumulation of debris. The present study explores the topographical features of the Drang Drung and Pensilungpa glaciers and investigates how topography affects their response to climate change. Additionally, a comparison is made between these glaciers with others in the basin to assess their representativeness of the region. The study utilized Landsat Imagery and ASTER GDEM data from 1976 to 2020. The results revealed that the mean accumulation area ratio (AAR) for Drang Drung and Pensilungpa was 54% and 49%, respectively, during this period. Drang Drung has lost 8.16 km2 (10.73%) of its area, while Pensilungpa has lost 2.25 km2 (9.84%) of its area. The debris cover of Pensilungpa increased from 1.86 km2 in 1976 to 2.32 km2 in 2020, whereas the debris cover area of Drang Drung has increased comparatively more, from 4.01 km2 to 4.76 km2. Within the same time frame, the snowline altitude (SLA) shifted upward by an average of 104 m and 88 m for Drang Drung Pensilungpa, respectively. Further, our findings revealed a substantial connection between the size of glaciers and the speed at which their area is diminishing. The mean slope was identified as a key factor in influencing the rate at which the area is lost, and the retreat rates of the glaciers. The reduction in glacial area, increased debris coverage, and changes in SLA are key indicators of ice volume loss under prevailing climatic conditions. The present study recommends that long-term field-based data and the incorporation of multi-temporal satellite imagery are crucial to mitigate uncertainties in detecting changes in Himalayan glaciers. These approaches would contribute to a more accurate understanding of glacial changes, and would aid in forecasting future scenarios considering ongoing global warming trends.