Evaluation of the probable permafrost distribution of Kinnaur district, Himachal Pradesh.

Permafrost is an Essential Climate Variable (ECV) as designated by the World Meteorological Organization (WMO) because of its vulnerability to changing climate conditions. The extent and distribution of permafrost in the Indian Himalayan area are mainly unknown. In this study we have produced probable permafrost map of Kinnaur district, Himachal Pradesh. Rock glaciers, mean annual air temperature (MAAT), and elevation were used as proxies to map the probable permafrost area of Kinnaur district. We prepared a rock glacier inventory of Kinnaur district using Google Earth and mapped a total of 247 rock glaciers covering an area of 171.5 km2. We used SRTM DEM data to determine elevation and Landsat 8 land surface temperature (LST) data to determine MAAT from 2013 to 2021. Our study shows 80.74% of rock glaciers were located in regions with MAAT < -1 °C. The minimum elevation of rock glaciers in the Kinnaur district ranges from 4000 to 6751 m above sea level. However, 67.43 % of rock glaciers can be found from 4700 to 5500 m above sea level. In this work, we used two scenarios to map the likely permafrost area:(1) where MAAT < -1 °C and Elevation> 4000 m, and (2) where MAAT < -1 °C and 4700 m ≤ Elevation ≤ 5500 m, respectively. According to our result probable permafrost area of the Kinnaur district is around 37.25%, but it is highly likely to be observed in approximately 15.65% of the area of the district which also covers most of the rock glaciers (around 2.5% area of Kinnaur district).