Working on Rikha Samba Glacier. Tika Gurung, Cryosphere Analyst, ICIMOD (right), gets help from mountain guides Pasang Sherpa (left) and Jit Bahadur Sherpa (centre) with hand-held ice drill for placing mass balance stakes. (Photo: Jakob Steiner/ICIMOD)

After a long break in fieldwork activity due to the COVID-19 pandemic, in September and November 2021 we were able to visit ICIMOD’s two main catchments in the Central Himalaya – the Hidden Valley and Langtang catchments − where we monitor high mountain hydrology, meteorology, and glaciology. In the Hidden Valley, located in the lower Mustang area just below Dhaulagiri peak, we retrieved data from the weather station on the glacier as well as mass balance readings from stakes on Rikha Samba Glacier at an elevation range of 5,416−6,515 masl. Even though the last visit was almost two years ago, we were able to retrieve nearly all measurements, which will improve our understanding of the mass change of ice in this relatively dry part of the Himalaya.

This was in contrast to our experience on Yala Glacier (5,168−5,661 masl) in the much wetter Langtang catchment, where more than half a meter of dry and sugary snow made work a lot more challenging as we needed to carve our path through the snow while paying close attention to potential crevasses. However, we were able to successfully measure nearly all the mass balance stakes.

A recent focus of our cryosphere monitoring relates to better understanding permafrost in our field sites. In Langtang, measurements were begun by installing sensors in 2014, and retrieving these sensors now provides us with the longest field measurements of permafrost in the Hindu Kush Himalaya (HKH) to date. While these measurements focused on high-elevation headwalls and rock glaciers, we have now installed sensors in soils at lower elevations, complemented by a small weather station that monitors climate as well as soil moisture. This will help us better understand the effect of changing permafrost on the hydrology of high mountain catchments in the HKH.

To compare how permafrost is different in the drier and higher Mustang area, the same sensors have been installed in that catchment. By installing sensors on two different sides of the Hidden Valley, we hope to investigate how the direction of the slope and amount of sun hitting it influences permafrost thaw, as well as where permafrost is continuous and where it may already be patchy.

As our time series in these catchments extend and as we continuously include more observations from different parts of the high mountain water balance, we gain a better understanding of how mountains work as a water tower, which will help us to understand how they will do so in the future.

Activities conducted under the Cryosphere Initiative are supported by the Government of Norway and the Swiss Agency for Development and Cooperation (SDC).

Jakob Friedrich Steiner

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