Glacier inventory of the Subansiri River Basin in the Brahmaputra catchment using Landsat satellite data: A case study of the Daisaphu Glacier changes

Abstract

Monitoring of glaciers of the Subansiri River Basin, regardless of geopolitical distribution, is pivotal, as the Subansiri River is one of the most important tributaries of the Brahmaputra River. However, the existing inventories in Eastern Himalayas mostly covered the Indian side, while most of the glacier regions are located in Tibet. For the first time, we constructed a complete, validated glacier and lake inventory using Landsat satellite data. We report 390 glaciers, where 191 are hanging glaciers, 59 ice aprons, 52 cirques, 40 niches, 37 valley glaciers, 9 icecaps and 2 outlet glaciers. The snow‐covered region occupies 0.96% of the total basin area. The study also reports that there are 52 glacial lakes, covering a cumulative area of 3.358 km2. Furthermore, the 37 valley glaciers cover an area of ~144 km2, with lengths ranging between 1.3 and 15.3 km, and a total ice reserve of ~11.95 km3. The largest glacier of the basin is the Daisaphu Glacier, which has an ice reserve of ~2.70 km3. We calculated the retreat of the Daisaphu Glacier to be 16 ma−1 between 1989 and 2014. However, the retreat has been seen to be enhanced, up to 21 ma−1 after 2009. We also estimated the recession rate of 27 other valley glaciers, apart from the Daisaphu Glacier. The recession rate of the glaciers ranges between 2 and 51 ma−1, where 30% of glaciers have retreated at a rate of <10 ma−1, 55% of glaciers have retreated at a rate of >10 ma−1 and 15% of glaciers show no frontal changes since 1985. The pro‐glacial moraine‐dammed lake of the Daisaphu glacier shows growth of 0.471 km2 in area, and an increase of 0.0833 km3 in water volume between 1978 and 2014. This inventory should help in the assessment of future water scenarios and climate change, as it will impact a large community downstream which is dependent on the glaciers which lie across two countries.