The distribution and hydrological significance of intact rock glaciers in the north-west Himalaya

ABSTRACT

Intact rock glaciers are common periglacial landforms that occur in cold alpine mountains and are often considered indicators of alpine permafrost. They can be both active and inactive, but both have ice in them and can be hydrologically significant. Little is known about the distribution of the rock glaciers in the Himalaya at basin-scale and content of water that can be hydrologically significant during the water-stressed months. We have found 967 intact rock glaciers covering an area of 306 km² in the river basins of Beas, Chenab, Ravi, Sutlej, and Yamuna. Out of these, around 77% are moraine derived and the rest are talus derived. Most of them occur in the elevation between 4000 and 4500 m having a slope of 10° to 30° with a westerly and south-westerly aspect. They start occurring from 3220 to 6206 m, in places with −10°C to 10°C mean monthly temperature and within 50–100 cm of average monthly precipitation. Their alignment suggests that these rock glaciers occur in the area with low to medium incoming solar radiations. These rock glaciers are generally found where the general rock types are low-grade metamorphic rocks and feldspar-rich intrusive granites occurring beyond the Main Central Thrust in the Higher Himalaya. Finally, we calculated about 8.5 billion m³ volume of water (ice water equivalent) stored in them, considering 60% of the volume of rock glaciers is ice.

KEYWORDS:

• Rock glaciers
• permafrost
• water equivalent
• north-western Himalaya
• India

Acknowledgements

Data used from the Google Earth Engine, Google Earth, the Global Land Ice Measurements from Space initiative (GLIMS) for their RGI glacier inventory product, European Centre for Medium-Range Weather Forecasts for ERA5 data, Shuttle Radar Topography Mission (SRTM) for their digital elevation model, National Aeronautics and Space Administration (NASA) for their open access product is greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Ministry of Human Resource Development (MHRD), Government of India.

Notes on contributors

Pritha Chakravarti

Pritha Chakravarti is a PhD student, Earth Sciences, Indian Institute of Technology, Gandhinagar 382355, Gujarat, India. Her research interests are glacier studies, hydrology, remote sensing, and GIS, geomorphology.

Vikrant Jain

Vikrant Jain is a Professor, Earth Sciences, Indian Institute of Technology (IIT) Gandhinagar 382355, Gujarat, India. His research interests are geomorphology and river science.

Vimal Mishra

Vimal Mishra is a Professor, Earth Sciences, Indian Institute of Technology (IIT) Gandhinagar 382355, Gujarat, India. His research interests are hydrological modelling, water resource management.