Recession and Development of Moraine-Dammed Lakes in the Chandra Basin of Great Himalayan Range, District Lahaul and Spiti, Himachal Pradesh, India

In the present study, three benchmark glaciers of the Chandra basin of the Himachal Himalayas were taken up for detailed glaciological investigation, which includes change in glacial attributes of the individual benchmark glaciers. Samudra Tapu glacier, the second largest glacier of the Chandra basin after Bara Shigri glacier, shows a total glacial retreat of 717 m within the period of 1980–2011. This represents an average retreat of 23.12 m in the last 31 years. Overall, 11.46% deglaciation of the Samudra Tapu glacier has been observed during the period of 1980–2011.The second benchmark glacier, the Gepang Gath glacier, is located in the southern side of the Great Himalayan range. The glacier has deglaciated by 20.70% from 1980 to 2011 and deciphers retreat of 507 m during the period under study with an average retreat of 16 m per year. The Batal glacier, the third benchmark glacier, has exhibited a retreat of 232.39 m with an average rate of 7.5 m per year for the period of 1980–2011. The glacier has deglaciated by about 24.24% during 1980–2001 and 8.71% during 2001–2011. Formation of moraine-dammed lakes near the snout of Samudra Tapu and Gepang Gath glacier and their rapid enlargement pose a GLOF-related threat for the downstream regions of the Chandra valley. Due to the peculiar geomorphological attributes of this glaciated area of the Chandra basin, field observation has also revealed formation of a paleo lake in the upstream region of the Batal area which further reveals that in the study area, the development of moraine-dammed lakes has been taking place in the recent past as well.