Mapping ground subsidence in Tso Kar valley, Ladakh as an indicator of permafrost degradation

Permafrost-related hazards through climate warming-induced degradation are anticipated to increase in the near future. While there is a large community of researchers working on the permafrost landscapes in the Arctic, Tibetan Plateau, and the European Alps, very few studies have looked at the state of permafrost in the Indian Himalayas and hence how these landscapes will change in the near future due to climate warming is quite unknown. Given the dependency of indigenous communities living in these vulnerable landscapes as well as the downstream impacts that this degradation can have on the Ganga and Brahmaputra valleys, it is quite crucial to develop a better understanding of this region in terms of permafrost current and future states. In this pilot study, we make an attempt to characterize permafrost degradation using SAR remote sensing technique to quantify ground subsidence in the Tso Kar area through interferometric analysis. Our results showed that ground subsidence for the snow-free months (June to September) during 2015- 2021 ranged from 37 mm to 102 mm. To understand the impact of micro climate on ground subsidence, we explored trends of air temperature, and soil temperature at different depths during 2000-2020 using model-derived data. In both the winter and summer seasons, air and soil temperature (including annual maximum and minimum temperatures) for all depths exhibit a linear increase in temperature suggesting climate warming. This novel approach can provide some new insights into permafrost degradation using ground subsidence as the indicator.