RESUMO
Cold-arid regions of the trans-Himalaya in the Indian Himalayan Region (IHR) is suspected to have a significant area of permafrost. However, information on the ground thermal regime of these permafrost areas is so far not available. This study bridge this knowledge gap by analysing the sub-surface thermal regime of selected sites in the Ganglass catchment, Ladakh range. Near surface ground temperature data recorded during September 2016 to August 2017 using 24-miniature temperature data loggers distributed across 12 plots and covering an elevation range of 4700-5612â¯m a.s.l. are used in this study. Permafrost characteristics including plausible ranges of thermal offset, active-layer thickness and mean annual ground temperature at 10â¯m depth were estimated by driving a one-dimensional heat conduction model. Two statistical models were used to map first order estimates of permafrost area in this 15.4â¯km2 catchment. Study suggest permafrost occurrence at all sites above 4900â¯m a.s.l. with active-layer thickness ranging from 0.1 to 4.2â¯m and the mean annual ground surface temperature ranging from between -10.0 and -0.85⯰C for these sites. MAAT at these sites range from -4.1 to -8.9⯰C and the surface offsets vary from -1.1 to 3.9⯰C. Estimated thermal offset range from -0.9 to 0⯰C. Both statistical models show comparable results and suggest 95% mean permafrost cover in the catchment above 4727â¯m a.s.l. These results strongly indicate existence of significant permafrost areas across the high elevations of the cold-arid regions of IHR. So far, permafrost processes are not considered for assessing present and future estimates of water and regional climate and as a causative factor for disasters like debris flows and landslides in the region. This study highlight the need for greater research efforts on Himalayan permafrost to have a comprehensive understanding of Himalayan cryosphere.