Spatial Changes in Glaciers Between 1965 and 2018 in Tirungkhad Watershed, Upper Sutlej Basin, Himachal Pradesh

This paper is an attempt to estimate spatial changes (area and length in the frontal area) in glaciers of Tirungkhad watershed in Upper Sutlej Basin. It also investigates the influence of topography on the changes in glaciers. High-resolution (spatial) Corona KH4A (1965), Landsat TM (1990) and Sentinel 2B (2018) imageries and Aster GDEM elevation data have been used in this study to estimate changes of the glaciers between 1965 and 2018. Total 41 glaciers with an area of 58.73 km(2)were mapped from Sentinel 2B imagery (2018). Due to cloud cover, 20 glaciers were selected for change calculation. During the period, 1965-2018, the glaciers have lost 1.95 +/- 1.06 km(2)or 5.58 +/- 3.16% (0.11 +/- 0.06%/year) of its total area. Average area loss rate was 0.037 +/- 0.020 km(2)/year during 1965-2018. The glacier area change showed almost uniform rate throughout the period 1965-2018 (- 0.038 +/- 0.053 km(2)/year during 1990-2018, and - 0.035 +/- 0.057 km(2)/year during 1965-1990). Average retreat rate of glaciers was 6.76 +/- 1.91 m/year during 1965-2018 (6.95 +/- 2.08 m/year during 1965-1990 and 6.60 +/- 1.74 m/year during 1990-2018). The topographic analysis showed that smaller glaciers had lost a higher percentage of area as compared to the larger glaciers.