Recent climate warming and changes in atmospheric circulation patterns have resulted in reductions in the duration of the snow cover season and the amount of water stored in the snowpack, as well as a widespread trend toward earlier spring melt and enhanced glacier melting. This trend, coupled with increasing demand for water, suggests growing conflict in the management of snowmelt-derived water supplies and the need for innovative assessment of critical hotspots and linkages between the discharge from snow and ice systems and rivers/aquifers. In response to requests from Member States, the IAEA’s Water Resources Programme developed and tested isotope tools for the quantitative assessment of interactions between water in snowpack, glaciers and permafrost, as well as in groundwater and surface water.
Seasonal snow cover occurs in about 25% of the Earth’s land surface, at high latitudes and high altitudes. The storage of precipitation in snowpack and glaciers, and its subsequent melting, substantially impacts the water cycle. In high altitude and latitude catchments, the majority of stream runoff may be generated by snowmelt, whereas in many temperate and humid catchments with seasonal snowpack, the main part of the annual runoff takes place as a result of the spring melt. Groundwater reservoirs recover during snow- and ice melt and stream discharge may reach its annual peak through contributions from both groundwater and overland flow. In catchments with permafrost, the soil may thaw and release water during summer down to a certain depth, below which the ground is permanently frozen. These processes, which are spatially and temporally still poorly understood, are instrumental for water and energy supply, mitigation of natural hazards, ecological stability and protection of local infrastructure in areas where snow, glaciers or permafrost are transformed into runoff.
In this context, this CRP aimed at: 1) developing and testing conceptual models of water recharge, storage, age, origin and pathways between snowpack, glaciers, permafrost and adjacent groundwater and surface waters under present climatic conditions in a variety of snow-and ice dominated mesoscale catchments, 2) assessing the use of environmental isotopes for verification and further development of snow- and ice melt models, 3) evaluating potential changes in surface water/groundwater interactions in snow, glacier and permafrost dominated areas under changing climatic conditions, 4) providing tools for sustainable management of water resources dominated by snow- and ice melt, and 5) raising awareness of the snow, glacier and permafrost dominated water resources in the Member States and their assessment through environmental isotopes.
In the CRP, isotopes were used to evaluate glacier contributions to streamflow as well as contributions of snowmelt to streamflow (Fig. 1). Variations in the isotopic composition of streamflow were used to identify the non-linear behaviour of runoff response. Importance of antecedent moisture conditions in determining the contribution of new water to stream flow was also studied. The contribution of melting glaciers was identified and studied using tritium. One of the important outcomes of the project was the development of a new type of sampler (Fig. 2), the Passive Capillary Sampler (PCS), and testing of the new snowmelt sampling technique. The CRP improved conceptual models for a variety of hydrological processes related to snowmelt, glacier and permafrost contributions to water resources and provided valuable examples that will be useful for future studies.
Researchers from 13 Member States participated in this project: Argentina, Canada, Georgia, Germany, India, Italy, Japan, Morocco, Pakistan, Russia, Slovakia, Slovenia and the USA.
For more information, please see the CRP description:
https://www.iaea.org/projects/crp/f32006