Geophysical-based assessment of hydrological sustenance in inhabited relict rock glaciers of the semi-arid Western Himalaya, India.

The future of High Mountain Himalayan Communities (HMHC) is increasingly precarious due to significant threats from retreating glaciers, diminishing snow cover, and thawing permafrost, which historically provided a stable and reliable source of freshwater. In response to declining water availability, indigenous communities are adopting innovative agro-pastoral strategies, including upslope migration. In the Western Himalayas, local populations are increasingly relocating to higher valleys in search of water and cultivable land, often settling atop rock glaciers. This study presents the first systematic field-based investigation of two such inhabited relict rock glaciers (IRRGs; Komic and Chicham) in the western Indian Himalaya, using geomorphological analysis and electrical resistivity tomography (ERT) to examine their internal structure. Isotopic analysis of meltwater was also conducted to determine its primary source. Field investigations revealed the presence of significant perennial supra-wetlands/ponds on the two landforms, even during the peak ablation season, serving as the source of livelihood for the inhabited community on these IRRGs. Since these two IRRGs are located in a periglacial environment, we conducted eight ERT profiles along the two IRRGs to assess the presence/absence of ice (permafrost) and determine the origin of water. The internal structure of the landforms exhibited well-defined, confined super-saturated zones, possibly developed by the thawing of internal palaeo-permafrost ice and sustained by infiltrated permafrost-thawed water from upstream. However, accelerating, elevation-dependent warming and lesser seasonal snowfall place these HMHC under severe threat to water security, with potentially catastrophic consequences for their livelihoods and survival. By providing the first comprehensive field-based assessment of IRRGs in this region, the study establishes these landforms as valuable modern analogues for other under-researched areas of the Himalayas, offering a crucial foundation for future research on water reserves, permafrost dynamics, and community adaptation strategies.