Understanding snow hydrological processes through the lens of stable water isotopes

Summary

This narrative review synthesises current understanding of how stable water isotopes elucidate snow hydrological processes throughout the snow particle's lifecycle. The authors examine how hydrometeorological conditions and ablation processes (sublimation, melting, wind redistribution) alter isotopic composition, and present case studies demonstrating isotopic tracing for tracking groundwater recharge seasonality, rain-on-snow flood contributions, and canopy-snow interactions. The synthesis concludes that isotopic approaches are particularly valuable for quantifying snow's role in water cycling in high-elevation and high-latitude catchments, whilst identifying remaining practical challenges and future research directions.

UK applicability

While UK snowfall is generally limited and irregular compared with high-elevation and high-latitude regions where isotopic snow hydrology is most pronounced, the isotopic tracing methodologies reviewed may have applicability in upland catchments (Scottish Highlands, Lake District, Snowdonia) during winter-spring transitions when snow processes are active, particularly for understanding groundwater recharge seasonality and rain-on-snow flood mechanisms.

Key measures

Stable water isotope ratios (δ²H and δ¹⁸O) in snowfall, snowpack, and snowmelt; isotopic fractionation during ablation processes (sublimation, melting, wind redistribution, avalanches); seasonal patterns in groundwater recharge; rain-on-snow flood contributions

Outcomes reported

The review synthesises how stable water isotope composition varies across the snow life cycle—from precipitation through snowpack to melt—and demonstrates isotopic tracing applications including groundwater recharge seasonality estimation, rain-on-snow flood contribution quantification, and canopy-snow exchange characterisation. The authors illustrate how isotopic approaches enable quantification of snow contributions to water cycling in high-elevation and high-latitude catchments.

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