Sonapani Glacier Recession over a Century from 1906-2016, Chandra Basin, Himachal Himalaya

In this study, the changes in snout and area of Sonapani glacier located in Chandra river valley, Himachal Himalaya has been studied over a century from 1906 to 2016. The study used a Survey Map (1906), Corona KH4-B (1971), Landsat 5 TM (1989), Landsat 7 ETM+ (2000) and Google Earth (2016) data images. In order to validate the satellite data images and other field studies, field work was carried out during 2014 in this area. The Survey Map (SM) of the Glacier was prepared by the Geological Survey of India (GSI) in 1906 and hence, demarcated its earliest snout position. Thus, the SM has been used as the base map for overall change detection studies. The study indicated a total glacier retreat of 1820 m at a rate of 16.5 ma(-1) over a time period of century from 1906 to 2016. During the different time intervals, the SG has indicated variable recessional patterns. For instance, the glacier has retreated by 991 m at a rate of 15 ma(-1) during 1906-1971, 202 m at a rate of 11.2 ma(-1) during1971-1989, 31 m at a rate 2.8 ma(-1) during 1989-2000 and 596 m at rate of 37.3 ma(-1) during 2000-2016. During the recent time period from 2000 to 2016, the rate of recession has increased rapidly. Due to this rapid recession of the glacier a major tributary towards the lower left side has also detached from it. The glacier also indicated an area loss of 29.7% (6.85 km(2)) from 1906 (23.9 km(2)) to 2016 (17.09 km(2)).