CR2025_36 Quantifying Contributions of Mountain Cryosphere Components to Groundwater Recharge Using Isotopic Analysis

Lead Supervisor: Maria Shahgedanova, Department of Geography and Environmental Science, University of Reading

Email: m.shahgedanova@reading.ac.uk

Co-supervisors: Andrew J. Wade, Department of Geography and Environmental Science, University of Reading; Dan Lapworth, British Geological Survey; Alan MacDonald, British Geological Survey

The mountain cryosphere and groundwater reservoirs supply water to vast populations around the world (Scanlon et al., 2023). These resources are particularly important in arid regions, bordered by glaciated mountains, where precipitation is minimal during the warm growing season. In mountain regions, water from melting snowpack, glaciers, permafrost, and rock glaciers sustains river flow and recharges major aquifers. The cryosphere resources are strongly affected by climate change and the loss of glacier ice, melt of permafrost, and diminishing duration of snow cover are well documented. These changes, combined with increasing demand for water, put pressure on the surface water resources. Groundwater abstraction often increases to compensate for the diminishing water availability putting the groundwater under pressure, too.

It was previously thought that groundwater storage in high mountains was limited. However, recent studies have demonstrated that substantial groundwater storage can exist in mountain areas which can provide an increased component of baseflow to rivers as glaciers retreat (Ó Dochartaigh et al., 2019) and can also be directly  connected to the lowland aquifers (van Tiel et al., 2024). Consequently, changes in snow cover, glacier volumes, and subsurface ice due to observed and projected climate change could also impact on groundwater resources.

While the importance of both cryosphere and groundwater resources for freshwater supply is clear, the connectivity between the mountain cryosphere and groundwater remains neither well understood nor well quantified. This project will examine the connectivity between the mountain cryosphere and groundwater in the Tien Shan Mountains, Central Asia. The following research questions will be addressed:
(i) What fraction of groundwater recharge is attributed to the components of the mountain cryosphere, including snow, glacier, permafrost, and rock glacier melt?
(ii) How does the connectivity between the mountain cryosphere and groundwater evolve downstream?
(iii) What are the temporal scales of these interactions?

Isotopic analysis will be the primary method used to address these questions. Stable water isotopes (δD, δ¹⁸O, and δ¹⁷O) will help evaluate the relative contributions of various sources (rainfall, streamflow, and components of the cryosphere) to groundwater along the elevation gradient. Tritium, and potentially carbon (¹⁴C) isotopes, will be used to characterise the age of groundwater and the temporal scale of interactions between the cryosphere and groundwater.

Sampling will be conducted in the demonstration catchments managed by the Central Asia Mountain Observatory Network (CAMON; https://research.reading.ac.uk/central-asia-mountain-observatory/). CAMON operates in four countries (Kazakhstan, Kyrgyzstan, Uzbekistan, and Tajikistan) and has an established isotopic sampling programme (Saidaliyeva et al., 2024) upon which this project will build. Sample analyses will be conducted at the University of Reading Stable Water Isotope Laboratory, at the International Atomic Energy Agency (IAEA) in Vienna, Austria and at the British Geological Survey (BGS) laboratories.

Training opportunities: 

The project involves fieldwork in several glacierized catchments in the Tien Shan Mountains, Central Asia run by the Central Asia Mountain Observatory Network (CAMON; https://research.reading.ac.uk/central-asia-mountain-observatory/) where the student will work alongside research teams from the Central Asian countries. The project will involve a placement at the International Atomic Energy Agency (IAEA) where the student will have an opportunity to work alongside the leading experts in isotope hydrology. The project will contribute to the Collaborative Research Project ‘Understanding Hydrological Processes in Glacierized Catchments under Changing Climate using Isotope Techniques’ (2024-2028) coordinated by the IAEA and delivered by 12 international research teams.

Student profile: 

This project would be suitable for students with a degree in Environmental Science, Earth Science and Geography or a closely related physical science.

Co-Sponsorship details:

This project will be applying for co-sponsorship from the British Geological Survey University Funding Initiative. A placement has also been arranged with the Isotope Hydrology Section at the International Atomic Energy Agency (IAEA) in Vienna, Austria.

References:

• Scanlon, B.R., et al, 2023. Global water resources and the role of groundwater in a resilient water future. Nature Reviews Earth & Environment, 4(2), pp.87-101. https://doi.org/10.1038/s43017-022-00378-6.
• Ó Dochartaigh, B. É., MacDonald, A. M., Black, A. R., Everest, J., Wilson, P., Darling, W. G., Jones, L., and Raines, M.: Groundwater–glacier meltwater interaction in proglacial aquifers, Hydrol. Earth Syst. Sci., 23, 4527–4539 (2019). https://doi.org/10.5194/hess-23-4527-2019.
• Saidaliyeva, Z. et al. (2024) Precipitation in the mountains of Central Asia: Isotopic composition and source regions. Atm. Chem. Phys. 24 (21). pp. 12203-12224.  doi: https://dx.doi.org/10.5194/acp-24-12203-2024.
• van Tiel, M., Aubry-Wake, C., Somers, L. et al. Cryosphere–groundwater connectivity is a missing link in the mountain water cycle. Nat Water 2, 624–637 (2024). https://doi.org/10.1038/s44221-024-00277-8.