Manifestation of topography and climate variations on long-term glacier changes in the Alaknanda Basin of Central Himalaya, India

Here, we present a detailed analysis of glaciers in the Alaknanda Basin, Central Himalaya, starting with a novel glacier inventory for 1968 and 2020 using high-resolution datasets of Corona and Sentinel-2A. Primarily, we examine the factors influencing changes in glacier characteristics. Results show that glacier area reduced to 683 +/- 47.81 km(2) from 742 +/- 44.4 km(2), and the number of glaciers increased to 116 from 98 between 1968 and 2020. The annual average recession of glaciers in the basin is 11.75 +/- 1.6 m/year for the corresponding period. Also noted is a significant increase (similar to 38%) in supraglacial debris cover extent of the glaciers during 2000-2020. Interestingly, smaller glaciers (< 5 km(2)) with lower altitude snout and higher slope have registered more significant area loss and higher retreat rate. Alongside topographic parameters, the significant deglaciation and fragmentation observed in the basin are augmented by the increase in winter-time temperature (0.03 degrees C/year) between 1968 and 2020.

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This study presents a detailed analysis of glaciers in the Alaknanda Basin, Central Himalaya, using high-resolution datasets. The results show that the glacier area has decreased and the number of glaciers has increased in the basin. There has also been a significant increase in the supraglacial debris cover extent of the glaciers. Smaller glaciers with lower altitude snout and higher slope have experienced more significant area loss and higher retreat rate, while topographic parameters and changes in winter-time temperature have influenced the deglaciation and fragmentation in the basin.