Rock glaciers represent hidden water stores in the Himalaya

In the high mountains of Asia, ongoing glacier retreat threatens human and ecological systems through reduced water availability. Rock glaciers are climatically more resistant than glaciers and contain valuable water volume equivalents (WVEQ). Across High Mountain Asia (HMA) the WVEQ of rock glaciers is poorly quantified, and thus their hydrological significance versus glaciers is unknown. Here we present the first systematic assessment of Himalayan rock glaciers, totalling similar to 25,000 landforms with an areal coverage of similar to 3747 km(2). We calculate the WVEQ of Himalayan rock glaciers to be 51.80 +/- 10.36 km(3). Their comparative importance versus glaciers (rock glacier: glacier WVEQ ratio) is 1:25, which means that they constitute hydrologically valuable long-term water stores. In the context of climate-driven glacier recession, their relative hydrological value will likely increase. These cryospheric stores should be included in future scenario modelling to understand their role in sustainable water management for HMA. (C) 2021 Published by Elsevier B.V.

Automated summary

The WVEQ of Himalayan rock glaciers is around 51.80 +/- 10.36 km(3), making them hydrologically valuable compared to glaciers, and their relative importance in terms of water resources may increase in the context of climate change.